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1.
Six endophytic strains isolated from surface-sterilized rice roots and stems of different rice varieties grown in the Philippines were characterized. They were analyzed by physiological and biochemical tests, SDS-PAGE of whole-cell protein patterns, DNA-DNA hybridization and 16S rDNA sequencing. SDS-PAGE of whole-cell patterns showed that the six isolates fell into two subgroups which were similar but not identical in protein patterns to S. marcescens. The phylogenetic analysis of 16S rDNA sequences of two representative strains IRBG 500 and IRBG 501 indicated that they were closely related to S. marcescens(more than 99% identity). Physiological and biochemical tests corroborated that the isolates were highly related to each other and to S. marcescens. In cluster analysis, all six isolates were clustered together at 93% similarity level and grouped closely with Serratia marcescens at 86% similarity level. DNA-DNA hybridization studies revealed that the isolates shared high similarity levels with S. marcescens(≥86% DNA-DNA binding), indicating they belong to the same species. However, the isolates differed in several biochemical characteristics from the type strain. They produce urease and utilize urea and L(+) sorbose as a substrate, which is different from all known Serratia reference strains. These results suggest that the six endophytic isolates represent a novel, non-pigmented subgroup of S. marcescens. 相似文献
2.
An endophytic Serratia marcescens strain SRM (MTCC 8708) isolated from the flowers of summer squash was found to be entomopathogenic against the larvae of
Helicoverpa armigera. Natural epizootic of this bacterial strain on the larvae collected from summer squash flowers ranged from 19.9 to 72.3%.
Under laboratory conditions, a dose of 6 × 10 10 c.f.u./ml diet induced 66.3% mortality of first instar H. armigera larvae. Similarly all other growth and development parameters of the insect were severely retarded in a dose-dependent manner.
The bacterium invaded the entire alimentary canal and haemolymph with successful replacement of all other gut-associated microflora.
There was a great reduction in midgut proteinase activity due to inhibition of five major proteinase isozymes by S. marcescens infection. Further, a synergistic interaction between chitinases isolated from this strain and Bacillus thuringiensis Cry1Ac toxin was observed. The present findings suggest that this plant-associated S. marcescens strain SRM could be suitably exploited for the management of H. armigera. 相似文献
3.
Enrichment-based methods targeted at uranium-tolerant populations among the culturable, aerobic, chemo-heterotrophic bacteria
from the subsurface soils of Domiasiat (India’s largest sandstone-type uranium deposits, containing an average ore grade of
0.1 % U 3O 8), indicated a wide occurrence of Serratia marcescens. Five representative S. marcescens isolates were characterized by a polyphasic taxonomic approach. The phylogenetic analyses of 16S rRNA gene sequences showed
their relatedness to S. marcescens ATCC 13880 (≥99.4% similarity). Biochemical characteristics and random amplified polymorphic DNA profiles revealed significant
differences among the representative isolates and the type strain as well. The minimum inhibitory concentration for uranium
U(VI) exhibited by these natural isolates was found to range from 3.5–4.0 mM. On evaluation for their uranyl adsorption properties,
it was found that all these isolates were able to remove nearly 90–92% (21–22 mg/L) and 60–70% (285–335 mg/L) of U(VI) on
being challenged with 100 μM (23.8 mg/L) and 2 mM (476 mg/L) uranyl nitrate solutions, respectively, at pH 3.5 within 10 min
of exposure. his capacity was retained by the isolates even after 24 h of incubation. Viability tests confirmed the tolerance
of these isolates to toxic concentrations of soluble uranium U(VI) at pH 3.5. This is among the first studies to report uranium-tolerant
aerobic chemoheterotrophs obtained from the pristine uranium ore-bearing site of Domiasiat. 相似文献
4.
The Oomycetous fungus Phytophthora colocasiae causing leaf blight of taro is widely distributed in India. Wide geographic range or sexual recombination provides genetic differentiation within this species. To determine how genetic variation is partitioned in P. colocasiae, 14 isolates were isolated from different regions of India, where the incidence of leaf blight is great. Molecular and biochemical techniques were employed for assessing and exploiting the genetic variability among isolates of P. colocasiae. Seven polymorphic enzyme systems revealed 23 isozyme patterns, each uniquely characterised by the presence or absence of electromorphs. Further, 10 oligodeoxynucleotide primers were selected for random amplified polymorphic DNA (RAPD) assays, which resulted in 123 polymorphic bands for 10 isolates of P. colocasiae. The data were entered into a binary matrix and a similarity matrix was constructed using a DICE similarity (SD) index. A UPGMA cluster based on SD values was generated using a NTSYS computer program. Shannon's index was used to partition genetic diversity. Similarly, isozymes and RAPDs yielded high estimates of genetic variability. Genetic diversity estimates via isozyme and RAPD pattern indicated 78.26% and 100%, respectively, total diversity among populations. This type of genetic variation in P. colocasiae indicates that variation due to asexual and/or possibly infrequent sexual mechanisms is possible and that genetic differentiation has taken place as a result of geographic isolation. The presence of larger than expected RAPD variation in isolates of P. colocasiae and the presence of distinct different zymotypes among these isolates suggests that genetic recombination (or less likely hybridisation) is at least possible in this fungus and that geographic differentiation has taken place. Even isolates obtained from the same habitat have different RAPD patterns, indicating that many populations of this fungus are made up of more than one genet and that few are derived clonally. 相似文献
5.
A total of 290 Candida isolates from patients were investigated for in vitro proteinase production. Overall, sixty percent of these strains were found to be proteinase producers. Of the C. albicans strains, 81.4% of the significant isolates in contrast to 19.7% of nonsignificant isolates were proteinase producers, the difference being statistically significant ( P<0.001). Amongst the different Candida species, the proteinase production was found not only in Candida albicans, but also in C. tropicalis, C. parapsilosis and C. glabrata. Thus this in vitro method of demonstration of proteinase may be a good adjunct to smear and culture examination in identifying pathogenic Candida species from anatomical sites where they can also be present as commensals. 相似文献
6.
We determined the susceptibility to oxidative stress and assessed the four virulence factors of the 38 Candida glabrata clinical isolates originating from two teaching hospitals in Slovakia. All the isolates were susceptible to hydrogen peroxide,
diamide, and 7-chlorotetrazolo[5,1-c]benzo[1,2,4]triazine (CTBT) inducing an increased formation of reactive oxygen species
in fungal cells. The mean relative cell surface hydrophobicity (CSH) of isolates was 21.9, ranging from 1.92 to 56.96. All
isolates showed biofilm formation. A high biofilm formation was observed among 60.5% of isolates. Positive correlations were
observed between biofilm formation and moderate values of CSHs. The 76.3% and 84.2% of isolates displayed varying degrees
of proteinase and phospholipase activity, respectively. These results demonstrate a differential distribution of factors contributing
to virulence of C. glabrata clinical isolates and point to their significance in pathogenesis that would be targeted by novel antifungals. 相似文献
7.
Twenty-three bacterial isolates were screened for their mineral phosphate–solubilizing (MPS) ability on Pikovskaya and National
Botanical Research Institute’s phosphate (NBRIP) agar. The majority of the isolates exhibited a strong ability to solubilize
hydroxyapatite in both solid and liquid media. The solubilization in liquid medium corresponded with a decrease in the pH
of the medium. Serratia marcescens GPS-5, known for its biocontrol of late leaf spot in groundnut, emerged as the best solubilizer. S. marcescens GPS-5 was subjected to ethyl methanesulfonate (EMS) mutagenesis, and a total of 1700 mutants, resulting after 45 minutes
of exposure, were screened on buffered NBRIP medium for alterations in MPS ability compared with that of the wild type. Seven
mutants with increased (increased-MPS mutants) and 6 mutants with decreased (decreased-MPS mutants) MPS ability were isolated.
All seven increased-MPS mutants were efficient at solubilizing phosphate in both solid and liquid NBRIP medium. Among the
increased-MPS mutants, EMS XVIII Sm-35 showed the maximum (40%) increase in the amount of phosphate released in liquid medium compared with wild-type S. marcescens GPS-5, therefore, it would be a useful microbial inoculant in groundnut cultivation. EMS III Sm W, a nonpigmented mutant, showed the lowest solubilization of phosphate among the 6 decreased-MPS mutants. 相似文献
8.
Some antifungal agents have shown to exert effects on expression of virulent factors of Candida as the production of secretory aspartyl proteinase (Sap). In this study, we sought to determine and to compare the influence
of fluconazole and voriconazole in proteinase activity of this microorganism. Thirty-one isolates obtained from oral mucosa
of human immunodeficiency virus positive (HIV +) patients were used in this study. The minimal inhibitory concentrations (MIC) of fluconazole and voriconazole were determined
using the broth microdilution method with RPMI 1640 medium and with yeast carbon base–bovine serum albumin (YCB–BSA) medium.
The Sap activity following by digestion of BSA as substrate was determined for four Candida albicans strains arbitrarily chosen according to susceptibility (susceptible or resistant) to fluconazole or voriconazole. Besides,
the SAP1 to SAP7 genes were screened by PCR for the same isolates that were determined by the Sap activity. In vitro susceptibility testing
using the two media presented similar MIC values. Increased Sap activity was observed in resistant isolates on presence of
drugs, but the Sap activity by susceptible isolates to azoles showed different behavior on the presence of drug. We detected
the presence of SAP1 to SAP7 genes from all susceptible or resistant C. albicans isolates. The present study provides important data about the proteinase activity and the presence of genes of SAP family in fluconazole and voriconazole susceptible or resistant C. albicans isolates. 相似文献
9.
A simple and practical method for typing and strain differentiation of herpes simplex virus (HSV) isolates, based upon analysis of the restriction endonuclease cleavage patterns of viral DNAs, was established by using unlabeled infected cell DNAs. The preparation of infected cell DNA is technically easier than that of purified viral DNA or of radiolabeled viral DNA. The method provides a powerful and practical tool for epidemiological and clinical studies of HSV infection, which can be performed in most diagnostic laboratories. In order to select suitable restriction endonucleases for the study of HSV isolates, the cleavage patterns of viral DNAs (strains MacIntyre, HF, UW-268, and SAV) with 12 enzymes were analyzed. Several enzymes, Bam HI, Kpn I, Pst I, Sal I, Sst I, and Xho I, were found to be useful for both typing and strain differentiation. With this method, HSV isolates from different individuals and from the same individual were analyzed by digestion of their infected cell DNAs with Bam HI. Six isolates from epidemiologically unrelated individuals were readily typed and differentiated from each other. Three isolates from the same individual showed very similar patterns. However, there was a small degree of difference between the first two isolates and the third isolate. 相似文献
10.
The aim of this study is to characterize extracellular phospholipase, proteinase, and esterase activities of Candida parapsilosis and C. metapsilosis isolated from clinical sources. Using PCR-restriction fragment length polymorphism (PCR–RFLP) of the secondary alcohol dehydrogenase
( SADH) gene fragment, we identified 20 as C. parapsilosis and 11 as C. metapsilosis from 31 isolates of C. parapsilosis species complex. No C. orthopsilosis was identified. A significantly high isolation frequency of C. metapsilosis (35.5%) was observed. Subsequent evaluation of enzymatic profile showed that 90.5% of C. parapsilosis and 91.7% of C. metapsilosis isolates were phospholipase producers. No difference in phospholipase activity was observed between two species. In terms
of proteinase, 81.0% of C. parapsilosis and 83.3% of C. metapsilosis isolates were positive. A higher level of proteinase activity was detected in C. parapsilosis. A remarkably high proportion of both C. parapsilosis and C. metapsilosis isolates exhibited strong phospholipase and proteinase activities, suggesting that the production of these two enzymes might
be common for them. On the other hand, both species similarly displayed rare esterase activity, with only one C. parapsilosis and two C. metapsilosis isolates being positive. Our data may further add to the confusion concerning the hydrolytic enzymatic activities of the
C. parapsilosis complex, and a wider collection of isolates and standardized methods may help to address the issue. 相似文献
11.
Ectohydrolytic enzyme activity (EEA) potential of 37 bacterial isolates derived from Orbicella annularis coral and 2 coral pathogens (Vibrio shilonii and V. coralliilyticus) was measured as model to infer the role of bacteria in organic matter processing within coral reef ecosystems. Bacterial cell-specific activities of eight enzyme types were measured after incubation in organic matter enriched and unenriched filtered seawater. Max value of activities of alkaline phosphatase, oleate-lipase, stearate-lipase and proteinase were 769.3, 327.6, 82.9 and 36.7 amol cell−1 h−1, respectively. Chitinase, α-mannosidase, α-glucosidase and β-glucosidase were generally lower by comparison (max 4.7–20.7 amol cell−1 h−1). No “super” isolates (bacteria expressing high levels of all ectohydrolases) were found suggesting a “specialization” among individual bacterial strains. Cumulatively, the 39 isolates tested displayed a broad range of cell-specific enzyme activities in both organic matter conditions. Culture-independent measurement of coral mucus layer EEA in O. annularis off a Panama reef showed comparable EEA patterns and diversity as the isolates. Volume-specific EEAs of all enzymes except alkaline phosphatase were 8–48 times higher in mucus than in surrounding seawater (SSW) samples. However, cell-specific EEAs in mucus were generally lower than in the SSW partly due to more abundant cells in the mucus than in SSW. For field samples, ≥ 85% of proteinase was cell-bound, while lipase was preferentially dissolved (40–96%). In general, the production of dissolved EEAs varied among measurements depending on sample source and enzyme types, suggesting a potential role of ectoenzyme size distribution in linking the whole reef ecosystem. Our findings support that the cumulative ectoenzyme expression (“ectoenzymome”) of the coral microbiome has the potential to maintain the functional resilience of the coral holobiont and response to stress through its contribution to organic matter processing within coral reef ecosystems. 相似文献
12.
The bacterial flora of the Oberea linearis (Coleoptera: Cerambycidae) was investigated and 13 different bacteria were isolated from O. linearis larvae. Seven of these bacteria were performed and characterized at species level and the rest of them were characterized
at genus level. In this study, we determined morphological and physiological characteristics of the bacterial isolates by
conventional and routine techniques, biochemical properties and metabolic enzyme profiles by API20E and Phoenix 1000A panel
test systems. Additionally, 16S rRNA gene sequence analysis was also performed to identify the isolates at the molecular level.
The isolates were identified as Acinetobacter calcoaceticus (Ol1), Enterobacter aerogenes (Ol2), Pseudomonas sp. (Ol3), Flavobacterium sp. (Ol4), Microbacterium sp. (Ol5), Enterobacter agglomerans (Ol6), Xanthomonas sp. (Ol7), Pseudomonas syringae (Ol8), Pseudomonas sp. (Ol9), Xanthomonas sp. (Ol10), Enterobacter cancerogenus (Ol11), Xanthomonas maltophilia (Ol12), and Serratia marcescens (Ol13). This is the first record of bacterial isolates (Ol5, Ol8, Ol11, Ol12) from any insect. All these bacteria were tested
against O. linearis larvae, and Serratia marcescens was found to cause the highest mortality (65%). On the other hand, we determined 90% mortality against this pest within four
days by utilizing spore and crystal mixture of Bacillus thuringiensis isolated from Melolontha melolontha. 相似文献
13.
A total of 416 samples comprising faecal samples from diarrhoeic cases of man, calves, sheep and goats, and urine samples from patients with urinary tract infections, were examined for the presence of enterobacteria of emerging pathogenic significance. Citrobacter freundii from 20, C. intermedius biotype-a from four, Serratia marcescens (serotype 05:H13, bactericin type 16) from one and Erwinia herbicola from two human stool samples were isolated. Only two urine samples yielded C. freundii. Citrobacter freundii was isolated from 10 and C. intermedius biotype-a from two calves. From sheep and goats, two isolates of C. freundii and three of C. intermedius biotype-a were obtained. None of these samples yielded Edwardsiella tarda or Yersinia enterocolitica. The examination of 99 toads and 145 wall lizards revealed that toads were reservoirs for C. freundii, C. intermedius biotype-a and Salmonella brijbhumi, whereas wall lizards were reservoirs for C. freundii, C. intermedius biotype-a, E. herbicola, Enterobacter cloacae and Salmonella spp. These bacteria were present in the range of 2.0 × 10 6 to 6.0 × 10 11 organisms per gram of intestinal contents. In addition, toads were carriers for Edwardsiella tarda (new serotypes 04167:H1 and 05159: nonmotile). None of the toads and wall lizards proved positive for C. intermedius biotype-b ( C. koseri), S. marcescens and Y. enterocolitica. C. freundii, C. intermedius biotype-a, E. herbicola and S. marcescens were resistant to penicillin and erythromycin whereas E. tarda isolates were also resistant to gentamycin, neomycin, colistin and sulfamethaxazole. 相似文献
14.
Serratia marcescens is a versatile opportunistic pathogen that can cause a variety of infections, including bacteremia. Our previous work established that the capsule polysaccharide (CPS) biosynthesis and translocation locus contributes to the survival of S. marcescens in a murine model of bacteremia and in human serum. In this study, we determined the degree of capsule genetic diversity among S. marcescens isolates. Capsule loci (KL) were extracted from >300 S. marcescens genome sequences and compared. A phylogenetic comparison of KL sequences demonstrated a substantial level of KL diversity within S. marcescens as a species and a strong delineation between KL sequences originating from infection isolates versus environmental isolates. Strains from five of the identified KL types were selected for further study and electrophoretic analysis of purified CPS indicated the production of distinct glycans. Polysaccharide composition analysis confirmed this observation and identified the constituent monosaccharides for each strain. Two predominant infection-associated clades, designated KL1 and KL2, emerged from the capsule phylogeny. Bacteremia strains from KL1 and KL2 were determined to produce ketodeoxynonulonic acid and N-acetylneuraminic acid, two sialic acids that were not found in strains from other clades. Further investigation of KL1 and KL2 sequences identified two genes, designated neuA and neuB, that were hypothesized to encode sialic acid biosynthesis functions. Disruption of neuB in a KL1 isolate resulted in the loss of sialic acid and CPS production. The absence of sialic acid and CPS production also led to increased susceptibility to internalization by a human monocytic cell line, demonstrating that S. marcescens phagocytosis resistance requires CPS. Together, these results establish the capsule genetic repertoire of S. marcescens and identify infection-associated clades with sialic acid CPS components. 相似文献
15.
The bacterium Serratia marcescens isolated from surface-sterilised Psoroptes cuniculi was found sensitive to the antibiotic Amikacin. Mites placed in this antibiotic for 48–72 h and then washed by centrifugation were found to be alive and S. marcescens-free. Two experimental infestations were undertaken in order to verify the ability of the S. marcescens-free mites to infect and to give ear skin lesions in healthy rabbits and to evaluate the differential ability of the S. marcescens-free and S. marcescens-infected mites to give ear skin lesions. All rabbits were found to be infested, but only rabbits infested with S. marcescens-free mites presented crusts in their ears, whereas mites and/or eggs were only detected in the ear cerumen of all rabbits infested with S. marcescens-infected mites. S. marcescens was isolated only from P. cuniculi mites taken from these latter rabbits. Results indicate that P. cuniculi mites do not need S. marcescens to live and to be able to infest a healthy rabbit. In addition, S. marcescens was not isolated from eggs and newly born larvae of S. marcescens-infected P. cuniculi, demonstrating that in a population of P. cuniculi this bacterium is not transmitted transovarially. 相似文献
16.
Summary To overproduce Serratia marcescens metalloprotease(SMP), various recombinant plasmids encoding SMP gene were constructed and the SMP productivities from the recombinant S. marcescens strains were examined. The recombinant S. marcescens strains indispensably required proteinaceous substrates such as casein for the extracellular production of SMP. We obtained maximum 9,100U/ml of SMP from the culture supernatant of S. marcescens ATCC27117 containing a regulatory plasmid pTSP2 encoding SMP gene fused with a strong trc99a promoter and its repressor gene lacI q, which is about 23 times higher than that of wild type strain. SMP produced from the recombinant S. marcescens(pTSP2) was 88.3% of total extracellular proteins. 相似文献
17.
We have investigated the production of proteinase and phospholipase by 20 different isolates of Paracoccidioides brasiliensis. Isolates were grown in Bacto-peptone, Dextrose, pH 5.5, agar slants, at 27 °C for 30 days, and cultures were transferred
onto Petri dishes containing basis medium and bovine serum albumin fraction V and sterile egg yolk as substrates for enzyme
production, and incubated at 27 °C. After 30 days net enzyme activity was visualized and quantitavely evaluated, measuring
a ratio between colony diameter and diameter of the transparent (proteinase) or white (phospholipase) ring zone surrounding
it. Results demonstrated that all isolates had the ability to produce proteinase and phospholipase, even though variability
in enzyme production was noted among different isolates of P. brasiliensis.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
18.
A high‐catalase‐producing strain, which was isolated from sludge containing hydrogen peroxide, was identified as Serratia marcescens SYBC08 by 16S rDNA sequence analysis. Serratia spp. was reported as non‐spore‐forming bacterium (except S. marcescens spp. sakuensis), but in our study electron microscopic observation revealed that the strain did produce spores. The content of the main fatty acid C 16:0 (14.8%) was significantly different from that of S. marcescens spp. sakuensis (33.2%) and S. marcescens spp. marcescens DSM 30121 T (34.8%), and the biochemical characteristics were not identical to those of S. marcescens spp. sakuensis. We speculate that the relatively high catalase activity and the spore structures may enable the strain to survive in a hydrogen peroxide environment. The most suitable carbon and nitrogen sources for the catalase production by S. marcescens SYBC08 were citric acid and corn steep liquor powder. A strategy of carbon metabolism regulation to enhance the catalase production was exploited. In the 7‐L fermenter, catalase production (20 353 U/mL) obtained in the presence of glucose and citric acid was 1.68‐ and 1.31‐fold higher than that obtained in the presence of glucose or citric acid, at equimolar carbon concentration. This production yield was much higher than that of many catalase‐producing strains, but only slightly lower than the production by Micrococcus luteus (34 601 U/mL). The results suggest that the new spore‐forming S. marcescens SYBC08 is a potential candidate for the production of catalase. 相似文献
19.
Restriction fragment length polymorphism (RFLP) analysis of a large number of Japanese isolates of Mycobacterium tuberculosis, containing isolates from small outbreaks of M. tuberculosis infection, and clinical isolates of M. bovis BCG, was carried out using a DNA probe derived from the insertion sequence IS 986. Clinical isolates of M. tuberculosis had a high degree of RFLP. The occurrences of the IS element varied from 1 to 19, the majority of isolates having 8 to 15 copies. Very similar fingerprints, however, were seen among strains isolated in the Kanto district. In particular, 3 strains were of the same pattern with or without an additional band. Similarity of the banding patterns of strains islated in the same district was observed in other areas. Six groups of strains, each group arising from a suspected common source of infection, were analyzed. Of these, 5 showed identical fingerprints within each group, but one showed different fingerprints. RFLP patterns of three strains isolated from individuals with lymphadenitis developed about two months after BCG vaccination, and one strain isolated from a bladder cancer patient with BCG instillation therapy were identical to those of BCG-Tokyo which had been used for the vaccination and therapy. These results confirm that RFLP analysis using IS 986 is a suitable tool for epidemiology of tuberculosis. 相似文献
20.
The occurrence of extended-spectrum-β-lactamase (ESBL)-producing strains in the community was investigated in a private laboratory
located in Juiz de Fora, Brazil. All enterobacterial isolates analysed were collected from urine of human patients between
the years 2000 and 2002. ESBL production was confirmed by double disk screening, combination disk method, and Etest ESBL strip.
The isoelectric point of each β-lactamase was determined in the crude extracts from each isolate. Detection of ESBL genes
was performed by polymerase chain reaction and the genetic relatedness of the isolates determined by pulsed-field gel electrophoresis
(PFGE). Of the 1,481 isolates, 22 (12 Klebsiella pneumoniae, 7 Escherichia coli, 1 Providencia stuartii, 1 Citrobacter freundii, and 1 Serratia marcescens) were identified as ESBL producers. The frequency of ESBL producers in the community was 1.48%. TEM-type enzymes were identified
in 95.4% of the isolates, followed by the SHV type. Seven strains produced CTX-M–type enzymes. This study showed that strains
producing multiple β-lactamases are also present in community-acquired bacterial isolates. Multiple strains exhibiting identical
PFGE genotypes were found in individual patients indicating a common source of acquisition. 相似文献
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