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1.
The purpose of this table is to provide the community with a citable record of publications of ongoing genome sequencing projects that have led to a publication in the scientific literature. While our goal is to make the list complete, there is no guarantee that we may have omitted one or more publications appearing in this time frame. Readers and authors who wish to have publications added to subsequent versions of this list are invited to provide the bibliographic data for such references to the SIGS editorial office.

Phylum Crenarchaeota

Phylum Deinococcus-Thermus

Phylum Proteobacteria

Phylum Tenericutes

Phylum Firmicutes

Phylum Actinobacteria

Phylum Spirochaetes

Non-Bacterial genomes

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2.
The purpose of this table is to provide the community with a citable record of publications of ongoing genome sequencing projects that have led to a publication in the scientific literature. While our goal is to make the list complete, there is no guarantee that we may have omitted one or more publications appearing in this time frame. Readers and authors who wish to have publications added to subsequent versions of this list are invited to provide the bibliographic data for such references to the SIGS editorial office.

Non-Bacterial genomes

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3.
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4.
The purpose of this table is to provide the community with a citable record of publications of ongoing genome sequencing projects that have led to a publication in the scientific literature. While our goal is to make the list complete, there is no guarantee that we may have omitted one or more publications appearing in this time frame. Readers and authors who wish to have publications added to this subsequent versions of this list are invited to provide the bibliometric data for such references to the SIGS editorial office.

Non-Bacterial genomes

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5.
The purpose of this table is to provide the community with a citable record of publications of ongoing genome sequencing projects that have led to a publication in the scientific literature. While our goal is to make the list complete, there is no guarantee that we may have omitted one or more publications appearing in this time frame. Readers and authors who wish to have publications added to subsequent versions of this list are invited to provide the bibliographic data for such references to the SIGS editorial office.

Phylum Euryarchaeota

Phylum Crenarchaeota

Phylum Deinococcus-Thermus

Phylum Proteobacteria

Phylum Tenericutes

Phylum Firmicutes

Phylum Actinobacteria

Non-Bacterial genomes

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6.
Strain HTCC2143 was isolated from Oregon Coast surface waters using dilution-to-extinction culturing. Here we present the genome of strain HTCC2143 from the BD1-7 clade of the oligotrophic marine Gammaproteobacteria group. The genome of HTCC2143 contains genes for carotenoid biosynthesis and proteorhodopsin and for proteins that have potential biotechnological significance: epoxide hydrolases, Baeyer-Villiger monooxygenases, and polyketide synthases.Strain HTCC2143 was sampled and isolated from surface waters (depth, 10 m) off the Coastal Pacific Ocean, Newport, OR (44°36′0"N, 124°6′0"W). In the course of dilution-to-extinction culture studies on coastal microbial communities, strain HTCC2143 was isolated in a pristine seawater-based medium (2). Phylogenetic analysis of 16S rRNA gene sequences placed strain HTCC2143 in the BD1-7 clade of the oligotrophic marine Gammaproteobacteria (OMG) group (2) and indicated that it is related to Dasania marina, isolated from Arctic marine sediment (3, 8). The HTCC2143 16S rRNA gene sequence is 95.3% similar to that of D. marina (AY771747) and is 96.6% similar to that of environmental gene clone 20m-45 (GU061297), taken from intertidal beach seawater of the Yellow Sea, South Korea. Other closer relatives of HTCC2143 included uncultured gammaproteobacterial clones from seafloor lava (clone P0X3b5B06 from Hawaii South Point X3, EU491383; 96.3%) (9), deep-sea sediment (Ucp1554 from the South Atlantic Ocean, Cape Basin, AM997645; 95.9%) (10), Yellow Sea sediment (95.8%; D8S-33, EU652559), and Arctic sediment (from Kings Bay, Svalbard, Norway; clone SS1_B_07_55, EU050825; 95.7%).Genomic DNA was prepared at Oregon State University and sequenced by the J. Craig Venter Institute. The finished contigs were automatically annotated with a system based on the program GenDB (5) and manually annotated as described in previous reports (7, 12). The annotation is available at http://bioinfo.cgrb.oregonstate.edu/microbes/. The draft genome of strain HTCC2143 comprises 3,925,629 bases and 3,662 predicted coding sequences with a G+C content of 47.0%. The genome of HTCC2143 was predicted to contain 40 tRNAs, 1 16S rRNA, 2 5S rRNAs, and 2 23S rRNA genes. Four genes for selenocysteine metabolism were found, including a selenophosphate-dependent tRNA 2-selenouridine synthase and an l-seryl-tRNA(Sec) selenium transferase (EC 2.9.1.1).Strain HTCC2143 had genes for a complete tricarboxylic acid cycle, glycolysis, a pentose phosphate pathway, and an Entner-Doudoroff pathway. Genes were present for a high-affinity phosphate transporter and a pho regulon for sensing of environmental inorganic phosphate availability, as well as genes from the NUDIX (nucleoside diphosphate linked to some other moiety X) hydrolase domain family (1) that reflects the metabolic complexity of prokaryotes (4). Genes for ammonium transporters, nitrate reductase, and sulfate reductase were also present in the HTCC2143 genome.Carotenoid and proteorhodopsin genes were also found in the genome, as well as genes for polyketide synthase modules and related proteins. Carotenoid and proteorhodopsin genes were reported previously from another member of the OMG group, strain HTCC2207, a SAR92 clade isolate (11). HTCC2143 also encoded two epoxide hydrolases, two cyclohexanone monooxygenases (CHMOs) and a cyclododecanone monooxygenase (CDMO). CDMOs and CHMOs are members of the Baeyer-Villiger monooxygenase (BVMO) family. BVMOs are “green” alternatives to the chemically mediated Baeyer-Villiger reactions that allow the conversion of ketones into esters or of cyclic ketones into lactones (6).This genome provides further evidence that dilution-to-extinction culturing methods that make use of low-nutrient media that are similar to the conditions of the natural environment can result in the isolation of novel, environmentally significant organisms with potential biotechnological value (13).  相似文献   

7.
Water channels formed by aquaporins (AQPs) play an important role in the control of water homeostasis in individual cells and in multicellular organisms. Plasma membrane intrinsic proteins (PIPs) constitute a subclass of plant AQPs. TgPIP2;1 and TgPIP2;2 from tulip petals are members of the PIP family. In this study, we overexpressed TgPIP2;1 and TgPIP2;2 in Pichia pastoris and monitored their water channel activity (WCA) either by an in vivo spheroplast-bursting assay performed after hypo-osmotic shock or by growth assay. Osmolarity, pH, and inhibitors of AQPs, protein kinases (PKs), and protein phosphatases (PPs) affect the WCA of heterologous AQPs in this expression system. The WCA of TgPIP2;2-expressing spheroplasts was affected by inhibitors of PKs and PPs, which indicates that the water channel of this homologue is regulated by phosphorylation in P. pastoris. From the results reported herein, we suggest that P. pastoris can be employed as a heterologous expression system to assay the WCA of PIPs and to monitor the AQP-mediated channel gating mechanism, and it can be developed to screen inhibitors/effectors of PIPs.The movement of water across cell membranes has long been thought to occur by free diffusion through the lipid bilayer. However, the discovery of the membrane protein CHIP28 in red blood cells has suggested the involvement of protein channels (29), and it is now well established that transmembrane water permeability is facilitated by aquaporins (AQPs), water channel proteins that are found in bacteria, fungi, plants, and animals (1, 7, 13, 24). AQPs contain six transmembrane α-helices and five connecting loops, and both the N and C termini are located in the cytosol. The monomers assemble into tetrameric complexes, with each monomer forming an individual water channel (11, 14, 24, 33). Apart from the exceptions of AQP11 and AQP12 from mice, as described by K. Ishibashi (15), AQPs have two signature Asn-Pro-Ala motifs, which are located in the second intracellular and the fifth extracellular loops, B and E.While 13 different AQPs have been identified in mammals (16), more than 33 AQP homologues have been discovered in plants (6, 17, 30). Plant AQPs fall into four subclasses: (i) the plasma membrane (PM) intrinsic proteins (PIPs), which are localized in the PM; (ii) the tonoplast intrinsic proteins (TIPs), which are localized in the vacuolar membranes; (iii) the nodulin-26-like intrinsic proteins; and (iv) the small basic intrinsic proteins (24). In Arabidopsis and maize, there are 13 PIPs, which can be divided further into two subfamilies, PIP1 and PIP2 (6, 17).The functions and mechanisms of regulation of plant AQPs have been extensively investigated (7, 13, 18, 24). There have been several reports on the water channel activity (WCA) of specific AQPs and their regulation by protein phosphorylation (3, 4, 8, 12, 18, 25, 32, 33). It has been shown that the WCA of the PIP2 member SoPIP2;1 from spinach is regulated by phosphorylation at two Ser residues (19, 33).The physiologically interesting temperature-dependent opening and closing of tulip (Tulipa gesneriana) petals occur concomitantly with water transport and are regulated by reversible phosphorylation of an undefined PIP (4, 5). Recently, four PIP homologues were isolated from tulip petals, and their WCAs have been analyzed by heterologous expression in Xenopus laevis oocytes (3). It has been shown that the tulip PIP TgPIP2;2 (DDBJ/EMBL/GenBank accession no. AB305617) is ubiquitously expressed in all organs of the tulip and that TgPIP2;2 is the most likely of the TgPIP homologues to be modulated by the reversible phosphorylation that regulates transcellular water transport and mediates petal opening and closing (3, 4). However, while the members of the PIP2 subfamily are characterized as water channels (6), TgPIP2;1 (DDBJ/EMBL/GenBank accession no. AB305616) shows no significant WCA in the oocyte expression system (3). There is growing interest in research on AQPs due to their crucial roles in the physiology of plants and animals (1, 16, 21-24, 26-28, 36). The assay of AQP channel activity is usually performed using either a X. laevis oocyte expression system (29) or a stopped-flow light-scattering spectrophotometer (35), both of which are not widely available. Furthermore, the complexity of these methods and requirement of expertise limit their high-throughput applications. In contrast, a Pichia pastoris expression system is simple to use, inexpensive, and feasible and can be used in high-throughput applications. Although a P. pastoris expression system has been shown to assay the WCA of a TIP (9), extensive research is necessary with other AQPs such as PIPs or AQPs present in intragranular membranes to establish whether this assay system can be used to characterize a water channel and study its regulation mechanisms. With this in view, in the study reported herein, TgPIP2;1 and TgPIP2;2 have been heterologously expressed in P. pastoris, and their WCAs have been assayed. The effects of several factors, such as osmolarity, pH, and inhibitors of protein kinases (PKs) and protein phosphatases (PPs), on the WCA of the recombinant P. pastoris have been investigated. Based on the results, we demonstrate that the P. pastoris heterologous expression system can be used to rapidly characterize PIP channels, to monitor the effects of mutations, and to score the effects of inhibitors and abiotic factors.  相似文献   

8.
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9.
In most cases, Escherichia coli exists as a harmless commensal organism, but it may on occasion cause intestinal and/or extraintestinal disease. Enterotoxigenic E. coli (ETEC) is the predominant cause of E. coli-mediated diarrhea in the developing world and is responsible for a significant portion of pediatric deaths. In this study, we determined the complete genomic sequence of E. coli H10407, a prototypical strain of enterotoxigenic E. coli, which reproducibly elicits diarrhea in human volunteer studies. We performed genomic and phylogenetic comparisons with other E. coli strains, revealing that the chromosome is closely related to that of the nonpathogenic commensal strain E. coli HS and to those of the laboratory strains E. coli K-12 and C. Furthermore, these analyses demonstrated that there were no chromosomally encoded factors unique to any sequenced ETEC strains. Comparison of the E. coli H10407 plasmids with those from several ETEC strains revealed that the plasmids had a mosaic structure but that several loci were conserved among ETEC strains. This study provides a genetic context for the vast amount of experimental and epidemiological data that have been published.Current dogma suggests the Gram-negative motile bacterium Escherichia coli colonizes the infant gut within hours of birth and establishes itself as the predominant facultative anaerobe of the colon for the remainder of life (3, 59). While the majority of E. coli strains maintain this harmless existence, some strains have adopted a pathogenic lifestyle. Contemporary tenets suggest that pathogenic strains of E. coli have acquired genetic elements that encode virulence factors and enable the organism to cause disease (12). The large repertoire of virulence factors enables E. coli to cause a variety of clinical manifestations, including intestinal infections mediating diarrhea and extraintestinal infections, such as urinary tract infections, septicemia, and meningitis. Based on clinical manifestation of disease, the repertoire of virulence factors, epidemiology, and phylogenetic profiles, the strains causing intestinal infections can be divided into six separate pathotypes, viz., enteroaggregative E. coli (EAEC), enteroinvasive E. coli (EIEC), enteropathogenic E. coli (EPEC), enterohemorrhagic E. coli (EHEC), diffuse adhering E. coli (DAEC), and enterotoxigenic E. coli (ETEC) (33, 35, 39).ETEC is responsible for the majority of E. coli-mediated cases of human diarrhea worldwide. It is particularly prevalent among children in developing countries, where sanitation and clean supplies of drinking water are inadequate, and in travelers to such regions. It is estimated that there are 200 million incidences of ETEC infection annually, resulting in hundreds of thousands of deaths in children under the age of 5 (55, 64). The essential determinants of ETEC virulence are traditionally considered to be colonization of the host small-intestinal epithelium via plasmid-encoded colonization factors (CFs) and subsequent release of plasmid-encoded heat-stable (ST) and/or heat-labile (LT) enterotoxins that induce a net secretory state leading to profuse watery diarrhea (20, 62). More recently, additional plasmid-encoded factors have been implicated in the pathogenesis of ETEC, namely, the EatA serine protease autotransporter (SPATE) and the EtpA protein, which acts as an intermediate in the adhesion between bacterial flagella and host cells (23, 32, 42, 46). Furthermore, a number of chromosomal factors are thought to be involved in virulence, e.g., the invasin Tia; the TibA adhesin/invasin; and LeoA, a GTPase with unknown function (14, 21, 22). E. coli H10407 is considered a prototypical ETEC strain; it expresses colonization factor antigen 1 (CFA/I) and the heat-stable and heat labile toxins. Loss of a 94.8-kb plasmid encoding CFA/I and a gene for ST enterotoxin from E. coli strain H10407 leads to reduced ability to cause diarrhea (17).Here, we report the complete genome sequence and virulence factor repertoire of the prototypical ETEC strain H10407 and the nucleotide sequence and gene repertoire of the plasmids from ETEC strain E1392/75, and we describe a novel conserved secretion system associated with the sequenced ETEC strains.  相似文献   

10.
The products of numerous open reading frames (ORFs) present in the genome of human cytomegalovirus (CMV) have not been characterized. Here, we describe the identification of a new CMV protein localizing to the nuclear envelope and in cytoplasmic vesicles at late times postinfection. Based on this distinctive localization pattern, we called this new protein nuclear rim-associated cytomegaloviral protein, or RASCAL. Two RASCAL isoforms exist, a short version of 97 amino acids encoded by the majority of CMV strains and a longer version of 176 amino acids encoded by the Towne, Toledo, HAN20, and HAN38 strains. Both isoforms colocalize with lamin B in deep intranuclear invaginations of the inner nuclear membrane (INM) and in novel cytoplasmic vesicular structures possibly derived from the nuclear envelope. INM infoldings have been previously described as sites of nucleocapsid egress, which is mediated by the localized disruption of the nuclear lamina, promoted by the activities of viral and cellular kinases recruited by the lamina-associated proteins UL50 and UL53. RASCAL accumulation at the nuclear membrane required the presence of UL50 but not of UL53. RASCAL and UL50 also appeared to specifically interact, suggesting that RASCAL is a new component of the nuclear egress complex (NEC) and possibly involved in mediating nucleocapsid egress from the nucleus. Finally, the presence of RASCAL within cytoplasmic vesicles raises the intriguing possibility that this protein might participate in additional steps of virion maturation occurring after capsid release from the nucleus.Cytomegalovirus (CMV) is a highly prevalent betaherpesvirus that can cause severe multiorgan disease in immunocompromised individuals (45). The ability of this virus to infect an exceptionally wide variety of different cell types substantially contributes to pathogenesis (5, 68). CMV tropism is largely determined by a finely tuned interplay between cellular and viral factors, many of which act at the earliest stages of infection (30, 68). We recently showed that the cellular protein vimentin is required for efficient onset of infection in primary human foreskin fibroblasts (HF). Interestingly, the degree of reliance on the presence and integrity of vimentin intermediate filaments is dependent on the virus strain, with the broadly tropic strain TB40/E being more negatively affected than the HF-adapted, attenuated strain AD169 (44).Serial passage of clinical isolates in HF or in endothelial cells (EC) has produced strains with different tropisms. The attenuated strains AD169 and Towne were developed as vaccine candidates by propagation in HF for more than 50 (AD169) and 125 (Towne) serial passages (19, 53, 61). During this process, both strains, compared to clinical isolates, accumulated multiple mutations and genomic deletions, resulting in the loss of more than 19 open reading frames (ORFs) (8). The number of serial passages in HF of another commonly used strain, Toledo, has been more moderate (19, 54, 58). This, however, did not prevent the emergence of numerous genomic mutations, including the inversion of an ∼15-kb fragment (8, 16, 56). As a consequence of these changes, productive infections by AD169, Towne, and Toledo are largely restricted to HF. In contrast, propagation of clinical isolates in EC has yielded a series of strains with more-intact genomes and broader tropisms, such as TB40/E, VHL/E, and FIX (VR1814) (25, 60, 71). These strains retain the ability to grow in a wider variety of cell types, including EC, epithelial cells, and dendritic cells (DC), in addition to HF (23, 28, 59, 60, 68).The UL128, UL130, and UL131A gene products were recently identified as essential mediators of CMV infection of EC and epithelial cells (26, 72, 73) and of virus transfer from infected EC to monocyte-derived DC (23). Each of these proteins is independently required for the broader tropisms of EC-propagated CMV isolates (63, 64), and the presence of mutations affecting their functionality has been directly linked to the inability of AD169, Towne, and Toledo to initiate productive infections in EC and epithelial cells (26, 72, 73).We have shown that mature Langerhans-type DC differentiated in vitro from CD34+ hematopoietic progenitor cells are highly permissive to direct infection with TB40/E or VHL/E, with 48 to 72% of cells in culture expressing the viral immediate-early genes IE1 and IE2 at 48 h postinfection (hpi) (28). In contrast, only 2 to 5% and 0% of mature Langerhans cells were IE1/IE2 positive after exposure to Towne and Toledo, respectively. However, productive infection was detected in 12 to 17% of cells infected with AD169, despite the fact that this strain lacks expression of the UL131A gene as a consequence of a frameshift mutation (26). These results suggested the existence of additional viral genes with products involved in mediating tropisms for specific cell types, such as DC. To identify possible candidates, we compared the amino acid sequence of each ORF found in the genome of TB40-BAC4, a sequenced clone of the TB40/E strain in a bacterial artificial chromosome (BAC) (GenBank accession number EF999921) (69), to the sequence of each ORF found in AD169 and AD169-BAC (accession numbers X17403 and AC146999) (10, 49), Towne and Towne-BAC (accession numbers FJ616285, AC146851, and AY315197) (17, 18, 49), and Toledo-BAC (accession number AC146905) (49). The product of a putative ORF, originally identified by Murphy et al. and named conserved ORF 29 (c-ORF29) (49), was considered of particular interest because the amino acid sequence of the putative protein encoded by Toledo and Towne was extended by 79 residues compared to the putative protein encoded by TB40/E and AD169. This led to our speculation that that the extended version might result in a nonfunctional version of the c-ORF29-encoded protein. We thus focused our studies on the products of this ORF.Here, we show for the first time that CMV c-ORF29 encodes a protein expressed at early to late times postinfection (p.i.) and localizes to the nuclear rim in peculiar invaginations of the nuclear lamina and in cytoplasmic vesicular structures at late times p.i. Based on this localization pattern, we named this gene product nuclear rim-associated cytomegaloviral protein, or RASCAL. Surprisingly, no difference was observed in the distributions of RASCAL during infection of HF with TB40/E or Towne, suggesting that the intracellular trafficking of this protein is not affected by the presence of the additional residues at the C terminus of RASCAL from strain Towne (RASCALTowne). Ectopic expression of RASCAL in human embryo kidney 293T (HEK293T) cells further revealed that this protein requires the presence of the nuclear egress complex (NEC) member UL50 to reach the nuclear rim, while coimmunoprecipitation (co-IP) assays provided evidence for the existence of an interaction between RASCAL and UL50. These findings suggest that RASCAL may be a new component of the NEC with possible roles in remodeling the nuclear lamina during nucleocapsid egress from the nucleus.  相似文献   

11.
A multilocus sequence typing (MLST) analysis was used to examine the genetic structure and diversity within the two large extrachromosomal replicons in Medicago-nodulating rhizobia (Sinorhizobium meliloti and Sinorhizobium medicae). The allelic diversity within these replicons was high compared to the reported diversity within the corresponding chromosomes of the same strains (P. van Berkum et al., J. Bacteriol. 188:5570-5577, 2006). Also, there was strong localized linkage disequilibrium (LD) between certain pSymA loci: e.g., nodC and nifD. Although both of these observations could be explained by positive (or diversifying) selection by plant hosts, results of tests for positive selection did not provide consistent support for this hypothesis. The strong LD observed between the nodC and nifD genes could also be explained by their close proximity on the pSymA replicon. Evidence was obtained that some nodC alleles had a history of intragenic recombination, while other alleles of this locus had a history of intergenic recombination. Both types of recombination were associated with a decline in symbiotic competence with Medicago sativa as the host plant. The combined observations of LD between the nodC and nifD genes and intragenic recombination within one of these loci indicate that the symbiotic gene region on the pSymA plasmid has evolved as a clonal segment, which has been laterally transferred within the natural populations.Plants of the genus Medicago are legumes that often benefit from a mutualistic symbiosis with rhizobia. The most agriculturally significant species of rhizobia that nodulate these plants are Sinorhizobium meliloti (9) and Sinorhizobium medicae (22). Previously reported population genetic analyses of these bacteria have focused on the study of how allelic variants at multiple loci are distributed within and among natural populations (2, 3, 10, 26, 31, 32). This was also the focus of the present study, but it was extended by examining more loci in many more strains of both species of Sinorhizobium coupled with an analysis having a range of symbiotic genotypes. One goal was to determine if there were any obvious correlations between the megaplasmid genotypes observed and their symbiotic competence. A second goal was to determine if selection by their host plants may have influenced the evolution of their symbiotic relationships.The genes for symbiosis reside on the extrachromosomal replicons pSymA (1,354,226 nucleotides [nt]) and pSMED02 (1,245,408 nt) in the genomes of S. meliloti Rm1021 and S. medicae WSM419, respectively (GenBank accession no. AE006469 and CP000740, respectively). Besides these two plasmids, these two strains each harbor one other large extrachromosomal replicon, pSymB (1,683,333 nt) and pSMED01 (1,570,951 nt), respectively (GenBank accession no. AL591985 and CP000739, respectively).Multilocus sequence typing (MLST) (16) is a form of genomic indexing that is commonly used to study the population genetic structure and phylogenetic relatedness within diverse groups of bacteria. In this method, nucleotide sequences of a fixed set of common loci are obtained from a collection of strains, and polymorphic sites among these sequences are used to derive an allelic profile or sequence type (ST) for each genome. Comparisons of the resulting data can be used to infer phylogenetic relationships among the organisms in the sample population, and they also can be used to infer how evolutionary processes, such as recombination and selection, have shaped the genetic structure of the population. For example, levels of intergenic recombination among chromosomal genes in natural populations of Neisseria meningitidis reportedly are relatively high, while corresponding levels within populations of Staphylococcus aureus were low (28). Depending on the specific pairs of loci examined, the levels of linkage disequilibrium (LD) (a lack of intergenic recombination) among several chromosomally carried core genes of S. meliloti were reported to be generally moderate to high (26).The MLST approach has been used to confirm that the chromosomes of S. meliloti and S. medicae are sexually isolated (2, 3, 31) and to provide evidence that horizontal gene transfer (HGT) does occur between the symbiotic megaplasmids of these species (3, 32). It has also been used to demonstrate that levels of intergenic recombination, as indicated by linkage disequilibrium, differ between the three replicons of S. meliloti (26). Levels of intergenic recombination within the pSymB replicons of these strains are generally high, unlike the chromosomes and pSymA replicons within the same strains (26). Bailly et al. (3) hypothesized that the region of the pSymA plasmid that contains the nodulation (nod) genes is frequently transferred in natural populations. They also suggested that selective pressures from the host plant may have influenced both nod gene diversity and patterns of polymorphism across the entire nod gene region.In the present study, multilocus allelic variation of the two megaplasmids was examined among 231 Medicago-nodulating rhizobia that originated primarily from southwest Asia (10). Previously, 91 different chromosomal sequence types (STs) were identified among the same strains from sequence variation in 10 loci (31). This collection of strains had earlier been divided into two closely related groups based on results of multilocus enzyme electrophoresis (10), and this result was subsequently cited in support of separating the Medicago-nodulating rhizobia into the two species S. meliloti and S. medicae (22).The objectives of this study were (i) to use MLST to examine the genetic relationships within and among the large extrachromosomal replicons in S. meliloti and S. medicae, (ii) to estimate levels of intergenic and intragenic recombination in these replicons, (iii) to evaluate the nitrogen-fixing competence of representative symbiotic genotypes with Medicago sativa, and (iv) to determine whether positive (or diversifying) selection may have influenced the genetic structure of the megaplasmids.  相似文献   

12.
Zymomonas mobilis is an ethanol-producing alphaproteobacterium currently considered a major candidate organism for bioethanol production. Here we report the finished and annotated genome sequence of Z. mobilis subsp. mobilis strain NCIMB 11163, a British ale-infecting isolate. This is the first Z. mobilis strain whose genome, chromosomal and plasmid, is presented in its entirety.Zymomonas mobilis is a bacterium vigorously studied as a platform organism for bioethanol production in North America and other parts of the world. Z. mobilis converts sugars such as glucose or sucrose into ethanol and carbon dioxide to almost theoretical yields and to rates higher than those of yeasts (17). Genetically engineered strains that ferment pentoses in addition to naturally utilized hexoses also hold great promise for use in lignocellulosic biomass degradations (5, 22). Besides ethanol, Z. mobilis can produce other high-value chemicals such as sorbitol, levan, or phenylacetylcarbinol and has attracted interest for its unusual membrane steroid content (11). Lastly, Zymomonas is regarded as a safe organism and is even used for medicinal purposes (12, 20), which further facilitates its employment in large-scale biotechnological endeavors.The chromosomal sequence of the Z. mobilis subsp. mobilis industrial strain ATCC 31821 (ZM4) was recently published (19). Here we announce the first entire genome sequence of a Z. mobilis subsp. mobilis strain, that of the United Kingdom-originating strain NCIMB 11163 (B70) (20). Total DNA from NCIMB 11163 (16) was used for whole-genome shotgun sequencing at the U.S. DOE Joint Genome Institute. For this, an 8.7-kb DNA library and 454 and Solexa reads were used (http://www.jgi.doe.gov). Draft assemblies were based on 8,551 Sanger reads and 454 pyrosequencing to 20× coverage, whereas the Phred/Phrap/Consed software package was used for sequence assembly and quality assessment (6, 7, 9; http://www.phrap.com). After the shotgun stage, reads were assembled with parallel Phrap (High Performance Software, LLC), and misassemblies were corrected with Dupfinisher (10) or transposon bombing of bridging clones (Epicentre Biotechnologies, Madison, WI). A total of 144 primer walk reactions, five transposon bomb libraries, 53 PCR end reads, and two PCR shatter libraries were necessary to close gaps, resolve repetitive regions, and raise the quality of the finished sequence. The completed genome sequence of NCIMB 11163 was based on 11,048 reads, with an error rate of less than 6 bp out of 100,000 bp.Open reading frame prediction and annotation were performed using Prodigal (http://compbio.ornl.gov/prodigal/) and BLAST (1); tRNAscan-SE and RNAmmer (14, 15) were used for tRNA and rRNA recognition, respectively. Functional assignment of genes was performed by searching translated open reading frames against sequences in the SPTR (TrEMBL) (2), Pfam (8), TIGRFAMs (18), COG (21), and KEGG (13) databases.Z. mobilis NCIMB 11163 contains a single, circular chromosome of 2,124,771 bp and three plasmids, p11163_1, p11163_2, and p11163_3 of 53,380 bp, 40,818 bp, and 4,551 bp, respectively. The overall GC content of the chromosome is 46.83%, whereas those of the plasmids are 42.32%, 43.80%, and 36.37%, respectively. The entire genome of NCIMB 11163 contains 1,884 protein-encoding genes and 51 tRNA and nine rRNA genes, which are chromosomally located.The chromosome of NCIMB 11163 is 68,355 bp larger than that of ZM4 (GenBank accession number NC_006526) (19) and colinear at its largest part with that of ZM4 (genome structure comparisons were performed using ACT) (3). It bears several unique regions, among which are two genomic islands of ca. 25 and 79 kb, with no detectable nucleotide homology to same-species sequences and high regional similarity to chromosomal stretches of Paracoccus denitrificans PD1222 (GenBank accession number CP000489.1), Xanthobacter autotrophicus Py2 (GenBank accession number CP000781.1), and Gluconacetobacter diazotrophicus PAl 5 (GenBank accession number CP001189.1). Genome plasticity in NCIMB 11163 is further indicated by the presence of a type IV secretion system on the 79-kb island, syntenous to the Agrobacterium tumefaciens Ti (IncRh1) conjugal trb system (4), and also by multiple transposase and phage-related genes.In plasmids, housekeeping genes implicated in replication, active partitioning, and plasmid addiction are recognized, as well as genes involved in metabolism, transport, regulation, transposition, and DNA modification. Most notably, p11163_1 bears an arsenical resistance operon inserted in a type II secretion locus, whereas p11163_2, otherwise homologous to the 41-kb ZM4 plasmid (GenBank accession number AY057845), harbors a unique ca. 12-kb CRISPR insertion that interrupts nucleotide colinearity with the aforementioned replicon.  相似文献   

13.
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14.
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15.
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16.
In an effort to develop a safe and effective vaccine for the prevention of enterotoxigenic Escherichia coli (ETEC) F41 infections, we have developed a surface antigen display system using poly-γ-glutamate synthetase A (PgsA) as an anchoring matrix. The recombinant fusion proteins comprised of PgsA and fimbrial protein of F41 were stably expressed in Lactobacillus casei 525. Surface localization of the fusion protein was verified by immunoblotting, immunofluorescence microscopy, and flow cytometry. Oral inoculation of recombinant L. casei 525 into specific-pathogen-free BALB/c mice resulted in significant mucosal immunoglobulin A (IgA) titers that remained elevated for >16 weeks. High levels of IgG responses in sera specific for F41 fimbriae were also induced, with prominent IgG1 titers as well as IgG2a and IgG2b titers. The helper T-cell (Th) response was Th2-cell dominant, as evidenced by increased mucosal and systemic interleukin-4-producing T cells and a concomitant elevation of serum IgG1 antibody responses. More than 80% of the mice were protected against challenge with a 2 × 104-fold 50% lethal dose of standard-type F41 (C83919). The induced antibodies were important for eliciting a protective immune response against F41 infection. These results indicated that the use of recombinant L. casei 525 could be a valuable strategy for future vaccine development for ETEC.Enterotoxigenic Escherichia coli (ETEC) strains colonize the small intestine, secrete enterotoxins, and cause diarrhea. Colonization is facilitated by pili (fimbriae). Pili facilitate the adherence of ETEC to intestinal mucosa (27). Pilus adhesins that are known to be important in ETEC infections of neonatal animals are K88, K99, 987P, FY, and F41 (26, 28, 29, 38). F41 is less prevalent than K88, K99, or 987P and is usually accompanied by K99 (25). There is, however, strong suggestive evidence that F41 can mediate colonization by adhesion. Variants of a K99- and F41-positive porcine ETEC strain that have lost the K99 gene (29) and still carry the gene for and produce F41 are still virulent for newborn pigs (13).The previously conventional vaccine variability in levels of protective immunity may have been due to the lack of stimulation of appropriate mucosal immunity, since these vaccines were delivered parenterally. Mucosal immunization has proven to be an effective approach against the colonization of pathogens and their further spread to the systemic circulation (15, 34). Therefore, it is necessary to develop efficient and safe antigen vectors that will be able to trigger mucosal and systemic immune responses. One promising approach relies on the use of live bacterial vehicles (22). For mucosal immunization, lactic acid bacteria (LAB) are more attractive as delivery vehicles than other live vaccine vectors (e.g., Shigella, Salmonella, and Listeria spp.) (1, 3, 20, 21) because LAB are considered safe, they exhibit adjuvant properties, and they are weakly immunogenic (7, 9, 10, 12, 23, 41). In addition, extracellularly accessible antigens expressed on the surfaces of bacteria are better recognized by the immune system than those that are intracellular (18).It is now realized that the delivery of antigen to mucosal surfaces can induce a strong local immune response in mucosa-associated lymphoid tissue. For the surface display of antigens on Lactobacillus casei, we have developed an expression vector using the poly-γ-glutamate synthetase A (PgsA) gene product as an anchoring matrix. PgsA is a transmembrane protein derived from the poly-γ-glutamic acid synthetase complex (the PgsBCA system) of Bacillus subtilis (5, 6); in this system, the N terminus of the target protein was fused to the PgsA protein, and the resulting fusion protein was expressed on the cell surface (32). In this study, the F41 fimbrial gene of ETEC was inserted into the vector pHB:pgsA and displayed on the surface of L. casei. The oral vaccination of mice with the recombinant L. casei strain elicited systemic and mucosal immune responses. These immune responses against F41 provided protective immunity in mice challenged with virulent live infectious C83919 postimmunization. Moreover, we showed that mice orally immunized with recombinant L. casei anchoring F41 induced a Th2-type response to ETEC F41. The results of this study suggest a potential use for our surface expression system against other pathogens that are transmitted to mucosal systems.  相似文献   

17.
Bocavirus is a newly classified genus of the family Parvovirinae. Infection with Bocavirus minute virus of canines (MVC) produces a strong cytopathic effect in permissive Walter Reed/3873D (WRD) canine cells. We have systematically characterized the MVC infection-produced cytopathic effect in WRD cells, namely, the cell death and cell cycle arrest, and carefully examined how MVC infection induces the cytopathic effect. We found that MVC infection induces an apoptotic cell death characterized by Bax translocalization to the mitochondrial outer membrane, disruption of the mitochondrial outer membrane potential, and caspase activation. Moreover, we observed that the activation of caspases occurred only when the MVC genome was replicating, suggesting that replication of the MVC genome induces apoptosis. MVC infection also induced a gradual cell cycle arrest from the S phase in early infection to the G2/M phase at a later stage, which was confirmed by the upregulation of cyclin B1 and phosphorylation of cdc2. Cell cycle arrest at the G2/M phase was reproduced by transfection of a nonreplicative NS1 knockout mutant of the MVC infectious clone, as well as by inoculation of UV-irradiated MVC. In contrast with other parvoviruses, only expression of the MVC proteins by transfection did not induce apoptosis or cell cycle arrest. Taken together, our results demonstrate that MVC infection induces a mitochondrion-mediated apoptosis that is dependent on the replication of the viral genome, and the MVC genome per se is able to arrest the cell cycle at the G2/M phase. Our results may shed light on the molecular pathogenesis of Bocavirus infection in general.The Bocavirus genus is newly classified within the subfamily Parvovirinae of the family Parvoviridae (21). The currently known members of the Bocavirus genus include bovine parvovirus type 1 (BPV1) (17), minute virus of canines (MVC) (57), and the recently identified human bocaviruses (HBoV, HBoV2, and HBoV3) (4, 7, 36).MVC was first recovered from canine fecal samples in 1970 (10). The virus causes respiratory disease with breathing difficulty (14, 32, 49) and enteritis with severe diarrhea (11, 39), which often occurs with coinfection with other viruses (39), spontaneous abortion of fetuses, and death of newborn puppies (14, 29). Pathological lesions in fetuses in experimental infections were found in the lymphoid tissue of the lung and small intestine (14). MVC was isolated and grown in the Walter Reed/3873D (WRD) canine cell line (10), which is derived from a subdermoid cyst of an irradiated male dog (10). The full-length 5.4-kb genome of MVC was recently mapped with palindromic termini (60). Under the control of a single P6 promoter, through the mechanism of alternative splicing and alternative polyadenylation, MVC expresses two nonstructural proteins (NS1 and NP1) and two capsid proteins (VP1 and VP2). Like the NS1 proteins of other parvoviruses, the NS1 of MVC is indispensable for genome replication. The NP1 protein, which is unique to the Bocavirus genus, appears to be critical for optimal viral replication, as the NP1 knockout mutant of MVC suffers from severe impairment of replication (60). A severe cytopathic effect during MVC infection of WRD cells has been documented (10, 60).The HBoV genome has been frequently detected worldwide in respiratory specimens from children under 2 years old with acute respiratory illnesses (2, 34, 55). HBoV is associated with acute expiratory wheezing and pneumonia (3, 34, 55) and is commonly detected in association with other respiratory viruses (34, 55). Further studies are necessary, however, to identify potential associations of HBoV infection with clinical symptoms or disease of acute gastroenteritis (7, 36). The full-length sequence of infectious MVC DNA (GenBank accession no. FJ214110) that we have reported shows 52.6% identity to HBoV, while the NS1, NP1, and VP1 proteins are 38.5%, 39.9%, and 43.7% identical to those of HBoV, respectively (60).The cytopathic effect induced during parvovirus infection has been widely documented, e.g., in infections with minute virus of mice (MVM) (13), human parvovirus B19 (B19V) (58), parvovirus H-1 (25, 52), and BPV1 (1). In Bocavirus, cell death during BPV1 infection of embryonic bovine tracheal cells has been shown to be achieved through necrosis, independent of apoptosis (1). B19V-induced cell death of primary erythroid progenitor cells has been shown to be mainly mediated by an apoptotic pathway (58) in which the nonstructural protein 11kDa plays a key role (16). In contrast, the MVM-induced cytopathic effect has been revealed to be mediated by NS1 interference with intracellular casein kinase II (CKII) signaling (22, 44, 45), a nonapoptotic cell death. Oncolytic parvovirus H-1 infections can induce either apoptosis or nonapoptotic cell death, depending on the cell type (25, 40). Therefore, the mechanisms underlying parvovirus infection-induced cell death vary, although NS1 has been widely shown to be involved in both apoptotic and nonapoptotic cell death. The nature of the cytopathic effect during Bocavirus MVC infection has not been studied.Parvovirus replication requires infected cells at the S phase. Infection with parvovirus has been revealed to accompany a cell cycle perturbation that mostly leads to an arrest in the S/G2 phase or the G2/M phase during infection (30, 33, 42, 47, 65). MVM NS1 expression induces an accumulation of sensitive cells in the S/G2 phase (6, 46, 47). Whether MVC infection-induced cell death is accompanied by an alternation of cell cycle progression and whether the viral nonstructural protein is involved in these processes have not been addressed.In this study, we found, in contrast with other members of the family Parvoviridae, expression of both the nonstructural and structural proteins of MVC by transfection did not induce cell death or cell cycle arrest. However, the cytopathic effect induced during MVC infection is a replication-coupled, mitochondrion-mediated and caspase-dependent apoptosis, accompanied with a gradual cell cycle arrest from the S phase to the G2/M phase, which is facilitated by the MVC genome.  相似文献   

18.
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19.
The binding affinities and specificities of six truncated S-layer homology domain (SLH) polypeptides of mosquitocidal Bacillus sphaericus strain C3-41 with the purified cell wall sacculi have been assayed. The results indicated that the SLH polypeptide comprised of amino acids 31 to 210 was responsible for anchoring the S-layer subunits to the rigid cell wall layer via a distinct type of secondary cell wall polymer and that a motif of the recombinant SLH polypeptide comprising amino acids 152 to 210 (rSLH152-210) was essential for the stable binding of the S-layer with the bacterial cell walls. The quantitative assays revealed that the KD (equilibrium dissociation constant) values of rSLH152-210 and rSLH31-210 with purified cell wall sacculi were 1.11 × 10−6 M and 1.40 × 10−6 M, respectively. The qualitative assays demonstrated that the SLH domain of strain C3-41 could bind only to the cell walls or the cells treated with 5 M guanidinium hydrochloride of both toxic and nontoxic B. sphaericus strains but not to those from other bacteria, indicating the species-specific binding of the SLH polypeptide of B. sphaericus with bacterial cell walls.Crystalline bacterial cell surface layers (S-layers) cover the cell surfaces of many bacteria and archaea during all stages of growth and division. S-layers are composed of identical protein or glycoprotein subunits, which can assemble into two-dimensional crystalline arrays and exhibit oblique, square, or hexagonal symmetry (27, 28, 30). S-layers play key roles in the interaction between bacterial cells and environment as protective coats, molecular sieves, ion traps, cell adhesion mediators, and attachment structures (4, 21, 26, 29). Many S-layer proteins possess an N-terminal region with highly conserved amino acid sequences, which is called an S-layer homology (SLH) domain. An SLH domain contains one, two, or three repeating SLH motifs (6, 16). Each SLH motif is composed of about 55 amino acids containing 10 to 15 conserved residues (6, 17). It is suggested that the SLH domain of S-layer proteins is responsible for the binding of the S-layer subunits to the rigid cell wall layer (6, 15, 17, 19, 25), while the middle and C-terminal parts include the domains which are involved in the self-assembly process (27). In the case of Bacillaceae, secondary cell wall polymers (SCWP) are responsible for binding with SLH domains (13, 18, 19), but the SLH domains of some other bacteria have an affinity for peptidoglycan (33).Bacillus sphaericus is a gram-positive soil bacterium that represents a strictly aerobic group of mesophilic endospore-forming bacteria. Due to its specific toxicity to target mosquito larvae and the limited environment impact, some strains of this bacterium have been successfully used worldwide in integrated mosquito control programs. Previous studies revealed that some nontoxic strains of B. sphaericus contained S-layer proteins, and the S-layer proteins of B. sphaericus NCTC 9602, JG-A12, P1, and CCM 2177 have been studied in detail elsewhere (3, 7-9, 12, 22).B. sphaericus C3-41, a highly active strain isolated from a mosquito-breeding site in China in 1987, has different levels of toxicity against Culex spp., Anopheles spp., and Aedes spp. This strain belongs to the flagella serotype H5a5b, like strains 2362 and 1593 (32), and it has been developed as a commercial larvicide (JianBao) for mosquito larva control in China during the last decade (31). The genomic analysis of strain C3-41 revealed that an S-layer protein gene (slpC) (GenBank accession no. EF535606) exists on the chromosomal genome and its sequence is identical to the S-layer protein of B. sphaericus 2362 (1, 10), composed of 3,531 bp encoding a protein of 1,176 amino acids with a molecular size of 125 kDa. Although the binding function of S-layers has been identified in some nontoxic B. sphaericus strains (6, 11), it is not well documented in mosquitocidal B. sphaericus strains, and there are few reports on the binding function of each SLH motif and the binding specificity.In this study, the binding affinities and specificities of each SLH motif of S-layer protein from mosquitocidal B. sphaericus C3-41 alone and in combination with the different cell wall preparations have been investigated, and the species-specific binding of SLH polypeptide with bacterial cell walls has been demonstrated.  相似文献   

20.
Pantoea agglomerans is an ecologically diverse taxon that includes commercially important plant-beneficial strains and opportunistic clinical isolates. Standard biochemical identification methods in diagnostic laboratories were repeatedly shown to run into false-positive identifications of P. agglomerans, a fact which is also reflected by the high number of 16S rRNA gene sequences in public databases that are incorrectly assigned to this species. More reliable methods for rapid identification are required to ascertain the prevalence of this species in clinical samples and to evaluate the biosafety of beneficial isolates. Whole-cell matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) methods and reference spectra (SuperSpectrum) were developed for accurate identification of P. agglomerans and related bacteria and used to detect differences in the protein profile within variants of the same strain, including a ribosomal point mutation conferring streptomycin resistance. MALDI-TOF MS-based clustering was shown to generally agree with classification based on gyrB sequencing, allowing rapid and reliable identification at the species level.Pantoea agglomerans (20) is a ubiquitous plant-epiphytic bacterium that belongs to the family Enterobacteriaceae. While several strains are commercialized for biological control of plant diseases (23), the species also includes two phytopathogenic pathovars that carry distinctive virulence plasmids (32). P. agglomerans has a Jekyll-Hyde nature, being described also as an opportunistic human pathogen (30), which raises biosafety regulatory issues for the utilization of beneficial isolates (45). Clinical reports predominantly involve septicemia following penetrating trauma (16, 56) or nosocomial infections (14, 55). Clinical pathogenicity of this species has not been confidently confirmed (unfulfilled Koch''s postulates). Infections attributed to P. agglomerans are typically of a polymicrobial nature involving patients affected by other diseases (14) and may represent secondary contamination of wounds. Standard clinical diagnostics and identification rely mainly on biochemical profiling analysis or alternatively on 16S rRNA gene sequencing, despite the inadequacy of these techniques for precise discrimination within the Enterobacter and Pantoea genera (5, 20, 39). Problems with correct identification have been observed for automated systems such as the API 20E (24, 39) and Vitek-2/GNI+ (39, 40) (both from bioMerieux) or the Phoenix (11, 38) and Crystal identification systems (40, 48) (both from BD Diagnostic Systems).P. agglomerans is a composite taxon conglomerating former Enterobacter agglomerans, Erwinia milletiae, and Erwinia herbicola strains. Accurate identification is complicated by the unsettled taxonomy of the “P. agglomerans-E. herbicola-E. agglomerans” complex (45). Recent analyses based on gyrB sequencing, multilocus sequence analysis (MLSA) (4), and fluorescent amplified fragment length polymorphisms (fAFLP) (45) indicate that strains belonging to Enterobacter or Erwinia archived in culture collections are often erroneously assigned to P. agglomerans and are likely also misidentified in clinical diagnostics. False classifications of environmental P. agglomerans strains as related Pantoea species, including human- or plant-pathogenic P. ananatis, are also common (45). Inadequate biochemical identification methods and uncertainty regarding current taxonomy are revealed also by the excessive number of 16S rRNA gene sequences incorrectly assigned to P. agglomerans that can be retrieved from GenBank (Fig. ​(Fig.1).1). Sequencing of housekeeping genes, MLSA, and fAFLP are labor-intensive, time-consuming, and impractical approaches as routine diagnostic tools.Open in a separate windowFIG. 1.Taxonomy of putative P. agglomerans isolates based on 16S rRNA gene sequences retrieved from GenBank under the currently accepted species name or under the old basonyms Enterobacter agglomerans and Erwinia herbicola. Out of a total of 331 complete or partial sequences found, 263 could be aligned over their 1,240-bp central region resulting in a minimum evolution tree. For the analysis, gaps and missing data were eliminated only in pairwise sequence comparisons, resulting in a total of 1,114 positions. Nodal supports were assessed by 1,000 bootstrap replicates. Only bootstrap values greater than 50% are shown. The scale bar represents the number of base substitutions per site. The number of “P. agglomerans” sequences clustering with a given reference strain in shown in parentheses. Reference strains and clades containing reference strains are marked in bold, and the corresponding accession numbers are indicated between brackets. For the genus Erwinia the following reference strains were used: E. persicina HK204 [NR_026049.1], E. rhapontici 2OP2 [FJ595873], E. billingiae Eb661 [AM055711], E. tasmaniensis Et2/99 [AM292080], and E. amylovora FAW 23482 [AY456711].Whole-cell matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) (31) is an emerging technology for identification of bacteria (26, 46), fungi (17, 33), viruses (29, 51), insects (41), and helminths (42). MALDI-TOF MS-based identification can accurately resolve bacterial identity at the genus, species, and in some taxa subspecies levels (e.g., Salmonella enterica serovars, Listeria genotypes) (1, 18). Identity is based on unique mass/charge ratio (m/z) fingerprints of proteins, which are ionized using short laser pulses directed to bacterial cells obtained from a single colony embedded in a matrix. After desorption, ions are accelerated in vacuum by a high electric potential and separated on the basis of the time taken to reach a detector, which is directly proportional to the mass-to-charge ratio of an ion. This technique has been shown to deliver reproducible protein mass fingerprints starting from an aliquot of a single bacterial colony within minutes and without any prior separation, purification, or concentration of samples. Whole-cell MALDI-TOF MS is a reliable technique across broad conditions (e.g., different growth media, cell growth states), with limited variability in mass-peak signatures within a selected mass range (2,000 < m/z < 20,000) that does not affect reliability of identification (28, 31). MALDI-TOF MS profiles primarily represent ribosomal proteins, which are the most abundant cellular proteins and are synthesized under all growth conditions (47). MALDI-TOF MS identification profiles derived from several characterized strains for a given species are used to develop reference spectra (e.g., SuperSpectrum; AnagnosTec GmbH, Potsdam, Germany), and they include a subset of characteristic and reproducible markers. MALDI-TOF MS identification databases are currently available for a relatively wide range of clinical bacteria, and this method has become an accepted tool for routine clinical diagnostics due to enhanced simplicity, rapidity, and reliability. However, environmental bacteria, such as Pantoea, have not been widely evaluated using MALDI-TOF MS and are largely absent from identification databases, limiting the practical reach of this new technology.Our objectives were to develop a robust method for rapid identification of P. agglomerans and related bacteria based on MALDI-TOF MS and to compare MALDI-TOF MS results against those obtained from a phylogenetic analysis based on gyrB sequencing as well as against biochemical identification methods.  相似文献   

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