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1.
Serratia entomophila and Serratia proteamaculans cause amber disease of the grass grub Costelytra zealandica (Coleoptera: Scarabaeidae). Three genes required for virulence, sepABC, are located on a large plasmid, pADAP. The translated products of the sep genes are members of the toxin complex (Tc) family of insecticidal toxins that reside in the genomes of some Enterobacteriaceae. Each of the sep genes was placed either singly or as various combinations under the control of an inducible arabinose promoter, allowing their inductive expression. Western Immunoblot confirmed that each of the Sep proteins migrated at their predicted size on sodium dodecyl sulphate-polyacrylamide gel electrophoresis gel. Bioassays of sonicated filtrates derived from the various arabinose-induced para-SEP constructs showed that only when sepA, sepB and sepC were coexpressed were amber disease symptoms observed in grass grub larvae. Fourteen days after ingestion of the Sep protein filtrate, approximately 64% of the larvae reverted from a diseased to a healthy phenotype. Redosing the revertents with a fresh Sep protein filtrate reinitiated the amber pathotype, indicating that the Sep proteins are needed to be continuously present to exert an effect. 相似文献
2.
Gabriel A. Visnovsky - Present address: Visnovsky 《Biocontrol Science and Technology》2008,18(1):87-100
The bacterium Serratia entomophila (Enterobacteriaceae) has been developed as a commercially available biopesticide for control of the pasture pest Costelytra zealandica. The influence of culture medium composition, dissolved oxygen (DO) concentration and harvesting time were investigated in order to optimise the production of S. entomophila. In batch fermentations, highest yields were achieved using sucrose (40 g L-1) as the carbon source, followed closely by fructose and molasses. The effect of yeast extract (YE), marmite and bakery yeast as cell growth enhancers was also examined in both batch and fed-batch mode. Culture medium containing 20 g L-1 of YE (fed-batch) produced the highest cell density. No significant effect on cell yield was detected when cultures were supplemented with bakery yeast or marmite. The DO concentration influenced biomass production: a 5-fold increase in cell density was achieved when the concentration of DO was maintained in the range of 20-50% (5.7×1010 CFUs mL-1) in comparison with 1% (1.2×1010 CFUs mL-1). In cultures maintained at 1 and 20% DO concentration, cells harvested from the exponential growth phase survived for less than 2 weeks when stored at 4°C. In contrast, high cell survival (85-100%) was achieved when cells were harvested after they had entered the stationary growth phase. Recommendations are provided for the production of robust, high cell density cultures of S. entomophila. 相似文献
3.
Some strains of Serratia entomophila and S. proteamaculans cause amber disease of the New Zealand grass grub Costelytra zealandica (Coleoptera: Scarabaeidae), an important pasture pest in New Zealand. The disease determinants of S. entomophila, are encoded on a 153,404-bp plasmid, termed pADAP for amber disease associated plasmid. The S. proteamaculans strain 143 (Sp143) exhibits an unusual pathotype, where only 60-70% of C. zealandica larvae infected with the bacterium succumb to disease. DNA sequence analysis of the Sp143 pU143 virulence associated region identified high DNA similarity to the pADAP sep virulence associated region, with DNA sequence variation in the sepA gene and the variable region of the sepC component. No pADAP anti-feeding prophage orthologue was detected in the Sp143 genome. The region of pADAP replication was cloned and found to replicate in S. entomophila but not in Escherichia coli. DNA sequence analysis of the plasmid pSG348 repA gene from the French isolate of Serratia grimesii, identified 93% DNA identity to the pADAP repA gene. A comparison of the pU143 virulence associated region with the completed pADAP nucleotide sequence is given. 相似文献
4.
Qun Yan Peter Hoi-Fu Yu Hua-Zhong Li 《World journal of microbiology & biotechnology》2005,21(6-7):1255-1258
Summary A simplified HPLC detection method for tetrodotoxin and its biosynthesis by Serratia marcescens was investigated. With 0.04% phosphoric acid as mobile phase, tetrodotoxin could be detected by HPLC equipped with a UV detector
at a lower limit of 1 mg/l. After being cultivated in an improved ORI medium for a few days, Serratia marcescens was found to be capable of producing tetrodotoxin, and this was confirmed by both HPLC, and mouse bioassay. 相似文献
5.
Amber disease in the grass grub (Costelytra zealandica White) (Coleoptera: Scarabaeidae), caused by strains of the bacteria Serratia entomophila or S. proteamaculans, is characterised by cessation of feeding and clearance of the midgut. Analysis of the midgut enzyme activity in diseased grass grub larvae showed that proteolytic activity was reduced to low levels. The endopeptidases, trypsin, elastase, and chymotrypsin, were all markedly reduced in activity whereas the exopeptidases (leucine-aminopeptidase and carboxypeptidase A and B) were much less affected. There was no effect on the non-proteolytic enzymes, esterase and alpha-amylase. Sequential analysis of enzyme levels in the gut during onset of disease showed that proteolytic activity dropped after cessation of feeding and preceded gut clearance. In starved, uninfected larvae enzyme activity levels remained high, indicating that decline in enzyme activity is not associated with absence of food and cessation of feeding, but with the onset of disease. 相似文献
6.
H.S. Gatehouse J.T. Christeller S.D.G. Marshall 《Journal of invertebrate pathology》2009,101(3):215-221
Amber disease of the New Zealand grass grub Costelytra zealandica (Coleoptera: Scarabaeidae) is caused by ingestion of pADAP plasmid carrying isolates of Serratia entomophila or Serratia proteamaculans (Enterobacteriaceae) and causes infected larvae to cease feeding and clear their midgut to a pale amber colour where midgut serine protease activities are virtually eliminated. Using bacterial strains and mutants expressing combinations of the anti-feeding (afp) and gut clearance (sep) gene clusters from pADAP, we manipulated the disease phenotype and demonstrated directly the relationship between gene clusters, phenotype and loss of enzyme activity. Treatment with afp-expressing strains caused cessation of feeding without gut clearance where midgut protease activity was maintained at levels similar to that of healthy larvae. Treatment with strains expressing sep-genes caused gut clearance followed by a virtual elimination of trypsin and chymotrypsin titre in the midgut indicating both the loss of pre-existing enzyme from the lumen and a failure to replenish enzyme levels in this region by secretion from the epithelium. Monitoring of enzymatic activity through the alimentary tract during expression of disease showed that loss of serine protease activity in the midgut was matched by a surge of protease activity in the hindgut and frass pellets, indicating a flushing and elimination of the midgut contents. The blocking of enzyme secretion through amber disease appears to be selective as leucine aminopeptidase and α-amylase were still detected in the midgut of diseased larvae. 相似文献
7.
ArecA clone was isolated from a cosmid library ofSerratia entomophila constructed in theEscherichia coli strain HB101. Subcloning and transposon mutagenesis were used to identify a 1.36 kb fragment containing therecA gene. A clonedrecA mutation, generated by transposon mutagenesis and the replacement of a portion of therecA gene with an antibiotic resistance cassette, was introduced into the chromosome via a marker exchange technique. TherecA strains created were deficient in DNA repair, homologous recombination and both the spontaneous and UV induction of prophages.S. entomophila recA strains showed continued pathogenicity towards the New Zealand grass grub,Costelytra zealandica. Simple procedures for further construction ofS. entomophila recA strains have been demonstrated. 相似文献
8.
Mulet M Gomila M Lemaitre B Lalucat J García-Valdés E 《Systematic and applied microbiology》2012,35(3):145-149
An entomopathogenic, Gram-negative bacterium isolated from a female specimen of the fruit fly Drosophila melanogaster was taxonomically characterised. Strain L48(T) was strictly aerobic, non-fermentative, oxidase and catalase positive, rod-shaped, and motile due to a polar inserted flagellum. Phylogenetic analysis of the 16S rRNA gene and three other housekeeping genes placed strain L48 (T) in the Pseudomonas putida phylogenetic group. DNA-DNA hybridisation studies together with phenotypic metabolic tests and MALDI-TOF MS analysis justified the proposal of strain L48(T) as a representative of a novel species, for which the name Pseudomonas entomophila sp. nov. is proposed. The type strain is deposited in culture collections under accession numbers CCUG 61470(T) and CECT 7985(T). 相似文献
9.
Jin-li Tao Xue-dong Wang Ya-ling Shen Dong-zhi Wei 《World journal of microbiology & biotechnology》2005,21(6-7):969-972
A Serratia marcescens mutant for prodigiosin production was obtained by u.v. mutation with rational screening methods and a two-step feeding strategy
was used to increase its productivity. In flasks, the mutant strain B6 gave a 2.8-fold higher prodigiosin production than
that of the parent strain with glycerol as a carbon source. In a 5-l bioreactor, with a two-step feeding strategy in which
glucose was selected as the initial carbon source in the fermentation media and glycerol was fed as a ‘prodigiosin inducer’,
it gave a 7.8 times higher prodigiosin production (583 mg/l) than the parent stain with the original cultivation mode. 相似文献
10.
To evaluate the roles of blaIMP and blaTEM genes in the resistance of Serratia marcescens against beta-lactams and to find the spreading ways of these genes, 19 clinical isolates of imipenem-resistant Serratia marcescens were analyzed. Six strains bore blaIMP and blaTEM genes on a single plasmid, as confirmed by transferring resistance determinants via conjugation and transformation, and by detecting bla genes with PCR analysis. The six strains showed two different genomic patterns on pulsed-field gel electrophoresis. All the transconjugants and transformants gained high-level resistance to ampicillin, cephalexin, cefoxitin and cefotaxime, and showed a reduced susceptibility to imipenem, but maintained full susceptibility to aztreonam. In addition, the expressions of blaIMP and blaTEM genes were constitutive, either in Serratia marcescens clinical isolates or in their transconjugants and transformants. These findings may explain the rapid spread of the above resistance determinants among Enterobacteriaceae via transmissible plasmids in the clinical setting. 相似文献
11.
Production of palatinose using<Emphasis Type="Italic"> Serratia plymuthica</Emphasis> cells immobilized in chitosan 总被引:1,自引:0,他引:1
In recent decades, the production of palatinose has aroused great interest since this structural isomer of sucrose has interesting potential. We describe a simple and effective method of immobilizing Serratia plymuthica cells in chitosan. The sucrose isomerase activity of immobilized preparations was enhanced many times by activation with fresh nutrient medium and subsequent drying. The preparations obtained were physically very stable with high enzyme activity and excellent operational stability. The effect of temperature, pH and substrate concentration on enzyme activity of the immobilized cells was investigated. Using immobilized cells, a complete conversion of sucrose (40% solution) into palatinose was achieved in 4 h in a "batch"-type enzyme reactor. The use of free or immobilized cells had no effect on the composition of the solution, in particular the sugar content. The palatinose content was 80% and that of trehalulose 7%. 相似文献
12.
Preobrazhenskaya Yu. V. Voskoboev A. I. Burd V. N. 《Russian Journal of Bioorganic Chemistry》2003,29(6):556-559
Heme- and metal-independent chloroperoxidase from Serratia marcescens W 250 is shown to be capable of catalyzing the p-nitrophenyl phosphate hydrolysis. The parameters of the phosphatase reaction are determined and inhibitors and activators of the process are found. A hypothetical mechanism of the hydrolysis of phosphoesters by heme- and metal-independent haloperoxidases is suggested. 相似文献
13.
Ruiz-Sánchez A Cruz-Camarillo R Salcedo-Hernández R Barboza-Corona JE 《Biotechnology letters》2005,27(9):649-653
Chitinolytic activity of Serratia marcescens Nima (130 U ml−1) was up to 43 times higher than those produced by other S. marcescens strains. This strain synthesized an endochitinase (Chi-60), an exochitinase (Chi-50) and a novel N-acetylglucosaminidase. This latter showed two putative isoforms (Chi-180.5 and Chi-180.8) with isoelectric points of 5 and 8.1, respectively. 相似文献
14.
Filimonova MN Gubskaya VP Nuretdinov IA Benedik MJ Cherepanova NA Leshchinskaya IB 《Biochemistry. Biokhimii?a》2001,66(3):323-327
The mechanism of action of p-chloromercuribenzoate (PCMB) on Serratia marcescens nuclease was investigated. The analysis showed that PCMB forms complexes with DNA. Binding of C7H5O2Hg+ to DNA changes the secondary structure of the DNA. These changes alter the enzymatic activity of S. marcescens nuclease, which was previously found to be sensitive to the secondary structure of the substrates. The nuclease activity was either suppressed or stimulated in the presence of PCMB depending on the C7H5O2Hg+ to nucleotide equivalent ratio. Binding of C7H5O2Hg+ to DNA did not form an abortive enzyme–substrate complex. Binding of Mg2+ to the C7H5O2Hg–DNA complex caused appropriate changes in secondary structure of the substrate. Since Mg2+ and C7H5O2Hg+, though differing in the type of metal cation, are similar in their mechanisms of influence on enzymatic activity of S. marcescens nuclease, the identity of other metal-containing effectors in their mechanism of action on Serratia marcescens nuclease is assumed. 相似文献
15.
The Crested Lark has a very complex taxonomy, partly as a result of a strong variation in plumage ground color seemingly linked with environmental factors. However, large variations in body size and bill shape further complicate the situation in the Maghreb. In this paper, we first present a set of hypotheses to explain patterns of morphological variation around the Mediterranean Sea. A phylogeographical analysis covering all major biogeographical areas in the species' range is then performed to test these scenarios. Three mtDNA groups with distinct geographical distribution were identified. The randonii clade (= G. (c.) randonii) is endemic from central Maghreb and is phylogenetically basal relative to cristata and senegallensis. These two latter groups are much more widespread. The cristata clade is found in NW Morocco, throughout Europe and W Asia and in NE Africa, while senegallensis regroups the populations sampled in the Western Sub-Saharan Africa and in NE Maghreb (E Algeria, Tunisia). A combination of genetic and paleoenvironmental evidences supports a scenario of allopatric differentiation of these two lineages outside the Maghreb, with subsequent range expansion leading to their secondary presence in the Maghreb. However, the alternative hypothesis of differentiation in two, or even three separate Maghreb refuges cannot be completely dismissed with the present data. Interestingly, the Sahara desert and the Gibraltar Strait did not act as permanent barriers to dispersal in this species. In addition, the populations in the Maghreb are consistently longer-billed than their closest relatives, suggesting a role for natural selection or phenotypic plasticity. 相似文献
16.
Molecular characterization of polyphosphate kinase (ppk) gene from Serratia marcescens 总被引:1,自引:0,他引:1
To understand the mechanism of phosphate accumulation, a gene encoding polyphosphate kinase (PPK) was cloned from the genomic library of Serratia marcescens by Southern hybridization. From the nucleotide sequence of a 4 kb DNA fragment, an open reading frame of 2063 nucleotides was identified encoding a protein of 686 amino acids with molecular mass of 70 kDa. The potential CRP binding site and pho box sequence were found upstream of the putative promoter in the regulatory region. The expression of PPK resulted in the formation of inclusion bodies and the product was active at low temperature. The E. coli strain harboring plasmid pSPK5 with ppk gene increased enzyme activity of polyphosphate kinase, resulting in increased accumulation of polyphosphate in E. coli. 相似文献
17.
Ingrid Ahrenholtz Michael G. Lorenz Wilfried Wackernagel 《Archives of microbiology》1994,161(2):176-183
A quantitative endonuclease assay, which relies on the introduction of single and double strand breaks into supercoiled plasmid DNA, was used to study the activity of the extracellular nuclease of Serratia marcescens SM6 in buffer and in groundwater. The parallel enzyme concentration-dependent production of relaxed and linear plasmid molecules suggests that the nuclease produces single and double strand breaks in duplex DNA. Bovine serum albumin stimulated the nuclease activity towards DNA and RNA and increased the stability of the enzyme against thermal inactivation. The DNase activity at 4 °C and 50 °C was almost half of that at the optimum temperature (37 °C). The nuclease was active in groundwater, although the specific activity was lower than in buffer. In a groundwater aquifer microcosm, mineral-adsorbed transforming DNA was substantially less accessible to the nuclease than was dissolved DNA. The data suggest that the extracellular nuclease of Serratia marcescens may contribute to DNA turnover in the environment and that adsorption of DNA to minerals provides protection against the nuclease.Abbreviations GW groundwater GWA groundwater aquifer 相似文献
18.
Birgitta Bremer Richard G. Olmstead Lena Struwe Jennifer A. Sweere 《Plant Systematics and Evolution》1994,190(3-4):213-230
The taxonomic positions ofRetzia, Desfontainia, andNicodemia have been much discussed, and all three genera have been included inLoganiaceae (Gentianales). We have made a cladistic analysis ofrbcL gene sequences to determine the relationships of these taxa toGentianales. Four newrbcL sequences are presented; i.e., ofRetzia, Desfontainia, Diervilla (Caprifoliaceae), andEuthystachys (Stilbaceae). Our results show thatRetzia, Desfontainia, andNicodemia are not closely related toLoganiaceae or theGentianales. Retzia is most closely related toEuthystachys and is better included inStilbaceae. The positions ofDesfontainia andNicodemia are not settled, butDesfontainia shows affinity for theDipsacales s.l. andNicodemia for theLamiales s.l. 相似文献
19.
We report two cases of severe endophthalmitis, which were caused by Serratia marcescens, and developed in the immediate postoperative period in two recipients of corneal grafts from the same donor. The cause of
the donor's death was massive CVA. He had been on mechanical ventilation for 12 days before he died, and had shown no sign
of infectious disease while in the hospital. Vitrectomies were performed in the recipients' eyes on the third day after corneal
transplantation. On the same day, and again 1day later, the transplanted eyes were injected intravitreally with vancomycin
and ceftazidime. Two months after surgery, both eyes developed phthisis. These cases are similar to other rare reported cases
describing the virulence of S. marcescens.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
Serratia marcescens mutants, which excrete Escherichia coli alkaline phosphatase (APase) encoded by the plasmid-bearing phoA gene, were isolated after mutagenesis by N-methyl--nitro-N-nitrosoguanidine. These mutants produced two to four times as much APase as did the parent strain under a phosphate-limiting condition, and more than 70% of the enzyme was released into the culture medium. In addition, overproduction and excretion of beta-lactamase was observed in these mutants. 相似文献