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1.
V. A. Lipasova E. E. Atamova M. A. Veselova N. N. Tarasova I. A. Khmel 《Russian Journal of Genetics》2009,45(1):30-34
The introduction into strain Pseudomonas chlororaphis 449 of plasmid pME6863 that contains the cloned gene for N-acyl-homoserine lactonase, AiiA, leads to the degradation of all three types of N-acylhomoserine lactones produced by this strain (N-butanoyl-homoserine lactone, N-hexanoyl-homoserine lactone, and N-3-oxo-hexanoyl-homoserine lactone). This causes a drastic reduction in the synthesis of phenazine pigment and decreases the ability of cells to migrate on the surface of nutrient medium. However, the antagonistic activity of P. chlororaphis 449 toward phytopathogenic fungi Sclerotinia sclerotiorum and Rhizoctonia solani is not only decreased, but is even slightly increased; no essential changes in the exoprotease activity were observed. It is assumed that one of the QS systems of P. chlororaphis 449 may exert the repression effect on the expression of genes, which determine the two latter cell activities. 相似文献
2.
M. A. Veselova V. A. Lipasova M. I. Ovadis L. S. Chernin I. A. Khmel’ 《Russian Journal of Genetics》2009,45(9):1055-1061
Gene vfr of Pseudomonas chlororaphis 449 previously described only in Pseudomonas aeruginosa was identified, cloned, and sequenced; its localization in the chromosome was determined. Amino acid sequence of the protein
encoded by gene vfr in P. chlororaphis 449 was shown to have a 83% identity with the Vfr protein of P. aeruginosa PAO1 and a 63% identity with the CRP protein of Escherichia coli. Amino acid residues that ensure the most important structural properties of the CRP protein, i.e., its binding to cAMP,
RNA polymerase, and DNA, were identical or highly conserved in Vfr proteins of P. aeruginosa and P. chlororaphis 449. The cloned vfr gene of P. chlororaphis 449 was complemented partially the mutation at gene crp in cells of E. coli AM306 enhancing ten times synthesis of β-galactosidase dependent on the CRP protein. Unlike P. aeruginosa, the Vfr protein in cells of P. chlororaphis 449 does not participate in the regulation of synthesis of N-acyl-homoserine lactones. 相似文献
3.
Kok-Gan Chan Cheng-Siang Wong Wai-Fong Yin Choon-Kook Sam Chong-Lek Koh 《Antonie van Leeuwenhoek》2010,98(3):299-305
A bacterial strain, KM1S, was isolated from a Malaysian rainforest soil sample by using a defined enrichment medium that specifically
facilitates selection of quorum quenching bacteria. KM1S was clustered closely to Bacillus
cereus by 16S ribosomal DNA sequence analysis. It degraded N-3-oxo-hexanoyl homoserine lactone and N-3-oxo-octanoyl homoserine lactone in vitro rapidly at 4.98 and 6.56 μg AHL h−1 per 109 CFU/ml, respectively, as determined by the Rapid Resolution Liquid Chromatography. The aiiA homologue, encoding an autoinducer inactivation enzyme catalyzing the degradation of N-acylhomoserine lactones, of KM1S was amplified and cloned. Sequence analysis indicated the presence of the motif 106HXDH-59 amino acids-H169-21 amino acids-D191 for N-acylhomoserine lactone lactonases. 相似文献
4.
Roberts DP McKenna LF Hu X Lohrke SM Kong HS de Souza JT Baker CJ Lydon J 《Archives of microbiology》2007,187(2):101-115
Strains of Enterobacter cloacae show promise as biological control agents for Pythium ultimum-induced damping-off on cucumber and other crops. Enterobacter cloacae M59 is a mini-Tn5 Km transposon mutant of strain 501R3. Populations of M59 were significantly lower on cucumber roots and decreased much more
rapidly than those of strain 501R3 with increasing distance from the soil line. Strain M59 was decreased or deficient in growth
and chemotaxis on most individual compounds detected in cucumber root exudate and on a synthetic cucumber root exudate medium.
Strain M59 was also slightly less acid resistant than strain 501R3. Molecular characterization of strain M59 demonstrated
that mini-Tn5 Km was inserted in cyaA, which encodes adenylate cyclase. Adenylate cyclase catalyzes the formation of cAMP and cAMP levels in cell lysates from
strain M59 were approximately 2% those of strain 501R3. Addition of exogenous, nonphysiological concentrations of cAMP to
strain M59 restored growth (1 mM) and chemotaxis (5 mM) on synthetic cucumber root exudate and increased cucumber seedling
colonization (5 mM) by this strain without serving as a source of reduced carbon, nitrogen, or phosphorous. These results
demonstrate a role for cyaA in colonization of cucumber roots by Enterobacter cloacae. 相似文献
5.
6.
Cardoso PG Ribeiro JB Teixeira JA de Queiroz MV de Araújo EF 《Journal of industrial microbiology & biotechnology》2008,35(3):159-166
The pectin lyase (PL) is an industrially important enzyme since it is used for maceration and clarification in the process
of fruit juice production in food industries. In order to increase the yields of pectin lyase we cloned the plg1 (pectin lyase 1) from Penicillium griseoroseum gene under the control of the strong constitutive promoter of the glyceraldehyde-3-phosphate dehydrogenase gene (gpdA) and the terminator region of the tryptophan synthetase (trpC) gene from Aspergillus nidulans (plasmid pAN52-Plg1) and transformed this construct into the P. griseoroseum strain PG63. One of the pAN52-Plg1 multi-copy transformants (strain 105) grown in culture medium containing glucose or sugar
cane juice showed PL activities of 4,804 or 5,202 U ml−1 respectively, which represented 57- and 132-fold increases. In addition, the apparent specific activity of PL produced by
this strain was much higher than the one observed for a commercial pectinase preparation. Evaluation of the extracellular
proteins in the culture supernatant of strain 105 by SDS-PAGE showed the presence of a clear and strong band of approximately
40 kDa that probably corresponds to PL. The enzyme yields reported here demonstrate that the system we developed is able to
express pectin lyase at levels comparable to, or exceeding, previously reported data. 相似文献
7.
Xiao Z Boyd J Grosse S Beauchemin M Coupe E Lau PC 《Applied microbiology and biotechnology》2008,78(6):973-981
Microbial genome sequencing has left a legacy of annotated yet uncharacterized genes or open reading frames, activities that
may have useful applications in health and/or the environment. We are interested in the discovery and characterization of
potentially new pectinolytic activities for the enzymatic retting of natural bast fibers such as hemp and flax. A highlight
in this study is the discovery of a cold-active pectate lyase among five pectate-lyase-encoding sequences and two polygalacturonase-encoding
sequences that we have cloned from the genomes of Xanthomonas campestris pv. campestris and Streptomyces coelicolor A3(2). Heterologous expression of these sequences as active pectate lyases and polygalacturonases required their subcloning
in Escherichia coli Rosetta™ cells. The most active recombinant pectate lyase (XcPL NP_638163), a cold-active pectate lyase (XcPL NP_636037),
and a polygalacturonase (XcPG NP_638805) were purified to near homogeneity and their kinetic parameters were determined. A
significant amount of pectin degradation products was shown to be released by the two pectate lyases but not the polygalacturonase
when hemp fiber pectin was used as substrate. Results of this study showed that genome data mining, besides an economical
approach to new gene acquisition, may uncover new findings such as the discovery of a cold-active pectate-lyase-encoding sequence
from X. campestris, a mesophilic microorganism. 相似文献
8.
Pochonins are antiviral and antiparasitic resorcylic acid lactones (RAL) structurally related to monorden. They were found
in the invertebrate-associated fungus Pochonia chlamydosporia. Their production and distribution was studied by means of High Performance Liquid Chromatography with UV-visual and mass
spectrometric detection (HPLC-UV/Vis and HPLCMS) in cultures of Pochonia species and further conidial fungi with Verticillium-like anamorphs that had until recently been included in Verticillium sect. Prostrata. The results support the recent generic segregation by Gams, Zare and co-workers because pochonins were found to occur exclusively
in species of the genus Pochonia. With few exceptions, the production of RAL appeared to be a rather constant feature in cultures of P. chlamydosporia from around the world. According to preliminary results, secondary metabolite profiles in strains of allied genera such as
Lecanicillium, Haptocillium and Rotiferophthora are different from those encountered in Pochonia. The alkaloid pseurotin A was found as main metabolite in several of the P. chlamydosporia isolates examined. As inferred from HPLC profiling data, strains of P. suchlasporia clustered into at least three chemotypes. The ex-type strain of P. suchlasporia var. catenata produced monorden, while several other strains produced metabolites whose HPLC-UV and HPLC-MS characteristics were similar
to the mycotoxins, aurovertin B and citreoviridin A. Yet different metabolites were detected in a third chemotype of P. suchlasporia. Differences in secondary metabolite profiles were also found in two strains of P. bulbillosa. While the ex-type strain was found devoid of all aforementioned compounds, CBS 247.68 contained the aurovertin-related metabolites
detected in part of the P. suchlasporia isolates. The sequence of the ITS nrDNA of CBS 247.68 was different from that of the type strain but identical to the sequences
of P. suchlasporia var. catenata. Several strains of the latter variety showed identical sequences, despite considerable variations in their HPLC metabolite
profiles. Minisatellite PCR fingerprinting was found useful to segregate Pochonia at species and strain level, pointing toward the existence of further, cryptic species. The possible chemotaxonomical importance
and ecological functions of secondary metabolites in these fungi is discussed. 相似文献
9.
It was investigated whether quorum sensing (QS) mediated by N-acylhomoserine lactones (AHLs) was important for heterotrophic bacteria from the littoral zone of the oligotrophic Lake Constance
for growth with organic particles. More than 900 colonies from lake water microcosms with artificial organic aggregates consisting
of autoclaved unicellular algae embedded in agarose beads were screened for AHL-production. AHL-producing bacteria of the
genus Aeromonas enriched in the microcosms but AHLs could not be detected in any microcosm. To test for a potential function of AHL-mediated
QS, growth experiments with the wild type and an AHL-deficient mutant of Aeromonas hydrophila in lake water microcosms were performed. Growth of both strains did not differ in single cultures and showed no mutual influence
in co-cultures. In co-cultures with a competitor bacterium belonging to the Cytophaga–Flavobacterium group, growth of both A. hydrophila strains was reduced while growth of the competitor bacterium was not affected. Exogenous AHL-addition did not influence growth
of the Aeromonas strains in any microcosm experiment. These results showed that AHL-mediated QS was not required for A. hydrophila during colonization and degradation of organic particles in lake water microcosms, suggesting that cell–cell signalling of
heterotrophic bacteria in oligotrophic waters relies on novel signal molecules. 相似文献
10.
DC Sabaté MJ Gonzaléz MP Porrini MJ Eguaras MC Audisio JM Marioli 《World journal of microbiology & biotechnology》2012,28(4):1415-1422
The aim of this work was to determine the in vitro effect of the mixture between the lipopeptide surfactin, synthesized by
Bacillus subtilis C4 (strain isolated from honey) and the most active vegetal extract from Achyrocline satureioides, a traditional medicinal plant, on local strains of Paenibacillus larvae, the agent of American Foulbrood in honeybees. Five P. larvae strains isolated in Córdoba, Argentina, were phenotypically characterized. These and 12 other P. larvae strains from different regions of Argentina were analysed. The antimicrobial activities of the essential oil, hexane (HE)
and benzene extracts from A. satureioides were assessed against P. larvae and the HE showed the highest anti-P. larvae activity. A combination of the biosurfactant surfactin, produced by B. subtilis C4, and the HE of A. satureioides revealed a synergistic action on P. larvae. The effective surfactin concentration in the mixture decreased from 32 to 1 μg ml−1 and the HE concentration from 32 to 4 μg ml−1, values similar or equal to minimal inhibitory concentrations observed for oxytetracycline. The fractional inhibitory concentration
index confirmed synergism in 4 strains and partial synergism in one strain. The combination of surfactin synthesized by B. subtilis C4 and the HE from A. satureioides could be a natural alternative to help beekeepers to combat the American foulbrood agent P. larvae. 相似文献
11.
12.
Christopher D. Skory 《Current microbiology》2003,46(1):0059-0064
A thalium chloride-resistant (TlClr) mutant strain and a sodium chloride-resistant (NaClr) mutant strain of the diazotrophic cyanobacterium Anabaena variabilis have been isolated by spontaneous and chemical mutagenesis by using TlCl, a potassium (K+) analog, and nitrosoguanidine (NTG), respectively. The TlClr mutant strain was found to be defective in K+ transport and showed resistance against 10 μM TlCl. However, it also showed sensitivity against NaCl (LD50, 50 mM). In contrast, neither wild-type A. variabilis nor its NaClr mutant strain could survive in the presence of 10 μM TlCl and died even at 1 μM TlCl. The TlClr mutant strain exhibited almost negligible K+ uptake, indicating the lack of a K+ uptake system. High K+ uptake was, however, observed in the NaClr mutant strain, reflecting the presence of an active K+ uptake system in this strain.
DCMU, an inhibitor of PS II, inhibited the K+ uptake in wild-type A. variabilis and its TlClr and NaClr mutant strains, suggesting that K+ uptake in these strains is an energy-dependent process and that energy is derived from photophosphorylation. This contention
is further supported by the inhibition of K+ uptake under dark conditions. Furthermore, the inhibition of K+ uptake by KCN, DNP, and NaN3 also suggests the involvement of oxidative phosphorylation in the regulation of an active K+ uptake system.
The whole-cell protein profile of wild-type A. variabilis and its TlClr and NaClr mutant strains growing in the presence of 50 mM KCl was made in the presence and absence of NaCl. Lack of transporter proteins in TlClr mutant strain suggests that these proteins are essentially required for the active transport and accumulation of K+ and make this strain NaCl sensitive. In contrast, strong expression of the transporter proteins in NaClr mutant strain and its weak expression in wild-type A. variabilis is responsible for their resistance and sensitivity to NaCl, respectively. Therefore, it appears that the increased salt
tolerance of the NaClr mutant strain was owing to increased K+ uptake and accumulation, whereas the salt sensitivity of the TlClr mutant strain was owing to the lack of K+ uptake and accumulation.
Received: 7 March 2002 / Accepted: 8 April 2002 相似文献
13.
X. Y. Yue J. S. Cao Z. M. Ma T. T. Liu X. P. Xiong S. E. Lin M. L. Lyu L. Huang 《Russian Journal of Plant Physiology》2018,65(3):364-371
Pectin methylesterases (PMEs) play an important role in modifying cell wall. PMEs catalyze the de-esterification of pectin, an important compound of cell wall, to affect fertility in plant reproduction. However, little especially molecular mechanism about pectin methylesterase is studied in recent years despite its importance to reproductive development in flower plant. Here the bioinformatics analysis of BcMF27 (Brassica campestris Male Fertility 27) (BRAD: Bra000541 GenBank: KT600012) sequence isolated from Brassica campestris L. ssp. chinensis showed its highly and characteristically conserved structure as a pectin methylesterase. Transient expression analysis in the onion epidermal cells revealed the product of BcMF27 was a transmembrane protein. Real-time RT-PCR and in situ hybridization suggested that BcMF27 was expressed in pollen grain and pollen tube. This study demonstrates that BcMF27 encodes a transmembrane pollen- and pollen tube-specific PME gene, and is also considered to help further understand the biological function of pectin methylesterases and the molecular mechanism of pollen development, pollen tube growth as a genic tool. 相似文献
14.
Huifang Ban Xinli Chai Yongjun Lin Ying Zhou Donghai Peng Yi Zhou Yulan Zou Ziniu Yu Ming Sun 《Plant cell reports》2009,28(12):1847-1855
Amorphophallus konjac is an important economic crop widely used in health products and biomaterials. However, this monocotyledonous plant’s production
is seriously restricted by soft rot disease. Some Bacillus thuringiensis strains generate an endocellular acyl homoserine lactonase (AiiA), which has inhibitory effect on soft rot pathogen through
disrupting the signal molecules (N-acylhomoserine lactones, AHL) of their Quorum Sensing system. The aim of our study is to obtain transgenic A. konjac expressing AiiA protein and exhibiting resistance to soft rot. But till now, there is not any report about exogenous gene
transformation in A. konjac. In this research, an Agrobacterium-mediated genetic transformation system was constructed. An aiiA gene was synthesized according to the codon usage in A. konjac. Embryogenic callus was infected with the A. tumefaciens strain EHA105 harboring the plant transformation plasmid pU1301 plus synthesized aiiA gene. After antibiotics screening, 34 plants were obtained. PCR analysis showed that positive amplified fragments were present
in 21 out of these 34 lines. Southern blot analysis indicated that aiiA gene had integrated into the genome of A. konjac. Western blotting demonstrated that the target protein of interest was reactive with the antibody against AiiA. Further disease
resistance detection revealed that all of the tested transgenic A. konjac lines exhibited high resistance to soft rot bacteria Erwinia carotovora subsp. Carotovora (Ecc) SCG1. The protocol is useful for the quality improvement of A. konjac through genetic transformation. 相似文献
15.
Wenjuan Yao Xiaozhao Deng Hui Zhong Miao Liu Pu Zheng Zhihao Sun Yun Zhang 《Journal of industrial microbiology & biotechnology》2009,36(7):911-921
Corynebacterium glutamicum strains are used for the fermentative production of l-glutamate. Five C. glutamicum deletion mutants were isolated by two rounds of selection for homologous recombination and identified by Southern blot analysis.
The growth, glucose consumption and glutamate production of the mutants were analyzed and compared with the wild-type ATCC
13032 strain. Double disruption of dtsR1 (encoding a subunit of acetyl-CoA carboxylase complex) and pyc (encoding pyruvate carboxylase) caused efficient overproduction of l-glutamate in C. glutamicum; production was much higher than that of the wild-type strain and ΔdtsR1 strain under glutamate-inducing conditions. In the absence of any inducing conditions, the amount of glutamate produced by
the double-deletion strain ΔdtsR1Δpyc was more than that of the mutant ΔdtsR1. The activity of phosphoenolpyruvate carboxylase (PEPC) was found to be higher in the ΔdtsR1Δpyc strain than in the ΔdtsR1 strain and the wild-type strain. Therefore, PEPC appears to be an important anaplerotic enzyme for glutamate synthesis in
ΔdtsR1 derivatives. Moreover, this conclusion was confirmed by overexpression of ppc and pyc in the two double-deletion strains (ΔdtsR1Δppc and ΔdtsR1Δpyc), respectively. Based on the data generated in this investigation, we suggest a new method that will improve glutamate production
strains and provide a better understanding of the interaction(s) between the anaplerotic pathway and fatty acid synthesis. 相似文献
16.
Hai-Ming Liu An Yan Xue-Hong Zhang Yu-Quan Xu 《World journal of microbiology & biotechnology》2008,24(9):1961-1966
The production of phenazine-1-carboxylic acid (PCA) and 2-hydroxyphenazine (2-OH-PHZ) makes Pseudomonas chlororaphis GP72 an effective biocontrol agent. In order to understand how production of PCA is regulated by RpoN, an insertional mutation
in rpoN has been made in P. chlororaphis GP72. Production of PCA in the rpoN mutant strain GP72N decreased both in King’s B medium and in Pigment Producing Medium. Moreover, the expression of the translational
fusion phzA′–′lacZ was reduced about 2-fold in GP72N compared to wild type strain, whatever the growth medium is. Complementation of rpoN gene in mutant GP72N restored its motility and its PCA biosynthesis ability. However, overexpression of RpoN had no major
effects on the expression of the RpoN-dependent phenotypes described in this study for P. chlororaphis GP72. These results suggest that RpoN is involved as a positive regulator in the regulation of PCA biosynthesis in P. chlororaphis GP72. 相似文献
17.
Effects of quorum sensing autoinducer degradation gene on virulence and biofilm formation of <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> 下载免费PDF全文
The aiiA gene from Bacillus thuringiensis was cloned into the Pseudomonas/E. coli shuttle vector and transformed into Pseudomonas aeruginosa strain PAO1. Western blotting showed that the AiiA protein was expressed in PAO1. After induction by IPTG for 6 h and 18
h, expression of the aiiA gene in PAO1 completely degraded the quorum sensing autoinducers N-acylhomoserine lactones (AHLs): N-oxododecanoyl-L-homoserine lactone (OdDHL) and N-butyryl-L-homoserine lactone (BHL). The reduced amount of AHLs in PAO1 was also correlated with decreased expression and
production of several virulence factors such as elastase and pyocyanin. AiiA expression also influenced bacterial swarming
motility. Most importantly, our studies indicated that aiiA played significant roles in P. aeruginosa biofilm formation and dispersion, as observed by the differences of the biofilm formation on liquid and solid surfaces, and
biofilm structures under a scanning electron microscope. 相似文献
18.
Biotransformation of flavonoids using Escherichia coli harboring nucleotide sugar-dependent uridine diphosphate-dependent glycosyltransferases (UGTs) commonly results in the production
of a glucose conjugate because most UGTs are specific for UDP-glucose. The Arabidopsis enzyme AtUGT78D2 prefers UDP-glucose as a sugar donor and quercetin as a sugar acceptor. However, in vitro, AtUGT78D2 could
use UDP-N-acetylglucosamine as a sugar donor, and whole cell biotransformation of quercetin using E. coli harboring AtUGT78D2 produced quercetin 3-O-N-acetylglucosamine. In order to increase the production of quercetin 3-O-N-acetylglucosamine via biotransformation, two E. coli mutant strains deleted in phosphoglucomutase (pgm) or glucose-1-phosphate uridylyltransferase (galU) were created. The galU mutant produced up to threefold more quercetin 3-O-N-acetylglucosamine than wild type, resulting in the production of 380-mg/l quercetin 3-O-N-acetylglucosamine and a negligible amount of quercetin 3-O-glucoside. These results show that construction of bacterial strains for the synthesis of unnatural flavonoid glycosides
is possible through rational selection of the nucleotide sugar-dependent glycosyltransferase and engineering of the nucleotide
sugar metabolic pathway in the host strain. 相似文献
19.
Limtong S Jindamorakot S Am-In S Kaewwichian R Nitiyon S Yongmanitchai W Nakase T 《Antonie van Leeuwenhoek》2011,99(4):865-871
20.
M. A. Veselova Sh. Klein I. A. Bass V. A. Lipasova A. Z. Metlitskaya M. I. Ovadis L. S. Chernin I. A. Khmel 《Russian Journal of Genetics》2008,44(12):1400-1408
Strain Pseudomonas chlororaphis 449, an antagonist of a broad spectrum of phytopathogenic microorganisms isolated from the maize rhizosphere, was shown to produce three phenazine antibiotics: phenazine-1-carboxylic acid (PCA), 2-hydroxylphenazine-1-carboxylic acid (2-OH-PCA), and 2-hydroxylphenazine (2-OH-PHZ). Two Quorum Sensing (QS) systems of regulation were identified: Phz/R and CsaI/R. Genes phzI and csaI were cloned and sequenced. Cells of strain 449 synthesize at least three types of AHL: N-butanoyl-L-homoserine lactone (C4-AHL), N-hexanoyl-L-homoserine lactone (C6-AHL), and N-(3-oxo-hexanoyl)-L-homoserine lactone (30C6-AHL). Transposon mutagenesis was used to generate mutants of strain 449 deficient in synthesis of phenazines, which carried inactivated phzA and phzB genes of the phenazine operon and gene phzO. Mutations phzA ? and phzB ? caused a drastic reduction in the antagonistic activity of bacteria toward phytopathogenic fungi. Both mutants lost the ability to protect cucumber and leguminous plants against phytopathogenic fungi Rhizoctonia solani and Sclerotinia sclerotiorum. These results suggest a significant role of phenazines in the antagonistic activity of P. chlororaphis 449. 相似文献