ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb05104.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb05105.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

A plate method for enumeratingStaphylococcus aureusis described which combines a 1‐h recovery period for stressed cells on a relatively non‐selective Baird‐Parker agar base followed by a 24‐h growth phase in a highly selective, supplemented Baird‐Parker medium added as an overlay. Tests with pure cultures showed satisfactory recovery of stressedStaph. aureusand other bacteria. Similar results were obtained with the conventional Baird‐Parker procedure and with the two‐stage isolation method for shrimps and poultry neck skins, but for raw minced meat, recoveries were higher with the combined method than with the conventional medium.All colonies visible after 24 h on the two‐stage medium can be counted asStaph. aureus, whereas longer incubation times and confirmatory tests are necessary to differentiate it from other organisms on conventional Bair

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb05106.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

A commercially available broth, with the addition of inhibitors, was used for the rapid impediometric detection of salmonellas in confectionery. Pre‐enrichment in skimmed milk was followed by lysine‐iron‐cystine‐neutral red broth in a Bactometer 123 system. Results were obtained 3d earlier than is possible with conventional microbiological tests. Some false positives were obtained predominantly withCitrobacter freundiibut this problem is also frequently encountered with traditional methods. Organisms responsible for false positives may be isolated and identified more rapidly than is possible by conventional

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb05107.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Previous investigations indicated that curing of a 7.4‐Md plasmid (pSMB74) resulted in concomitant loss of bacteriocin activity and immunity inPediococcus acidilacticiH. Transfer of pSMB74 to a gentamicin‐neomycin resistant (GmrNmr) derivative ofP. acidilacticiLB42, which was devoid of any plasmid DNA, required cell‐to‐cell contact on a solid mating surface and converted the strain to Bac+Bacrphenotype. Gene transfer processes such as transduction and transformation were ruled out from the experiment. Treatment of donor cells with chloroform did not allow the appearance of recombinant clones, confirming that viable cells were essential for this particular mechanism of genetic transfer. Transconjugants obtained from selective agar surface were subjected to plasmid isolation and agarose gel electrophoresis. Each of them exhibited plasmid size corresponding to pSMB74 of donor strain. All results suggested this genetic transfer similar to conjugation, and provided presumptive evidence for plasmid‐encoded bacteriocin activity and immunity inP. acid

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb05108.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Dot blot hybridization and in‐situ hybridization with DNA probes prepared from total genomic gonococcal DNA were compared with Gram staining and culturing for the detection of gonococci in urethral exudates. Fifteen of 60 patients were positive by at least one of the four methods. Gram staining and in‐situ hybridization scored best with 13 positives but culture and dot blot hybridization yielded only 10 and 9 positives respectively. The failure to detect gonococci in culture can be explained by overgrowth in one case and possibly self medication with ampicillin before culture in another. The in‐situ hybridization test is a fast and sensitive hybridization method for the detection of gonococci in urethral exudate fro

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb05109.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Human intestinal bacteria were grown in a 3‐stage continuous culture system on a medium containing complex polysaccharides and proteins as carbon and nitrogen sources. Selected bacterial populations were enumerated and glycosidase, protease and arylamidase activities measured. Comparison of arylamidase and glycosidase activities in the multichamber system (MCS) and faeces showed that the predominant faecal enzymes were also produced by bacteria growing in the MCS. After 48 d operation, porcine gastric mucin (5.8 g/d) was independently fed to vessel 1. Elevated levels of volatile fatty acid (VFA) formation showed that the glycoprotein was actively fermented. The increase in carbohydrate availability as a result of breakdown of the mucin oligosaccharides stimulated bacterial growth and activities. The enzymological measurements showed that mucin increased production of both cell‐bound and extracellular glycosidases, such as β‐galactosidase, α‐glucosidase and N‐acetyl‐β‐glucosaminidase. Protease activities were profoundly influenced by mucin. These were largely cell‐bound in non‐mucin cultures but were predominantly extracellular and collagenolytic when mucin was present. Experiments with protease inhibitors showed that cysteine proteases were the major cell‐bound and extracellular enzymes in both mucin and non‐mucin cultures, but that serine and metalloproteases were also present. The effect of mucin on arylamidase formation was less marked, although there was increased production of these enzymes in vessels 1 and 2 of the MCS. These results suggest that host‐produced substances such as mucin glycoprotein may play a role in modulating the growth and activity of bacteria growing in

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb05110.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The extractable protein antigens EA1 and EA2 ofBacillus anthraciswere prepared from electrophoresis transblots of SDS extracts of vegetative bacteria of the Sterne strain. Hyperimmune guinea‐pig antiserum against EA2 failed to react withB. anthraciscells in immunofluorescence (IF) tests. Guinea‐pig antiserum against EA1 (anti‐EA1) reacted strongly in IF tests with non‐encapsulated vegetative cell of 10 of 12 strains ofB. anthracisand with cells of strains ofB. cereusandB. thuringiensis.The unreactiveB. anthracisstrains were α‐Vollum‐1B–1 and Texas. Encapsulated cells ofB. anthracisstained poorly except for small bright regions. Absorption of anti‐EA1 with cells ofB. cereusNCTC 8035 and NCTC 9946 removed activity towards allB. cereusstrains tested, but only partly reduced cross‐reaction withB. thuringiensisstrains. Absorption of anti‐EA1 withB. thuringiensis4041 removed activity towards this strain andB. cereusstrains. Evidence is produced thatB. thuringiensiscells grown on nutrient agar possess more cross‐reacting antigens than cells grown in nutrient broth. The reaction of anti‐EA1 withBacillusspores immobilized in clumps on microscope slides was attributed to contaminating vegetative debris because well‐separated individual spores failed to react. A rapid IF test was developed allowing identification ofB. anthracissampled from overnight cultures on blood plates. When sodium dodecyl sulphate extracts ofB. anthracisvegetative cells were analysed on immunoblots (Western blots) by reaction with anti‐EA1, a number of bands were visualized in addition to the expected 91 kiloDalton EA1 band. Prior absorption of anti‐EA1 withB. cereusorB. thuringiensiscells resulted in the disappearance of most or all of the brands in blots of these species, but had less effect on blots of theB. anthracisstrains. All sixB. anthracisstrains that were blotted including α‐Vollum‐1B‐1 and Texas, could thus be distinguished fromB. cereusandB. thuringiensisby their differential reaction

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb05111.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The activities of three bacterial biotransformation enzymes (β‐glucuronidase, β‐glucosidase, nitrate reductase) were determined in suspensions of rat caecal contents or human faeces over the pH range 6–8. All three enzymes were influenced by pH, as exemplified by β‐glucosidase activity which diminished as pH increased. In other instances the rat and human flora showed distinct profiles, with nitrate reductase activity undetectable in human faeces below pH 6–6, whereas the rat caecal flora displayed optimal reduction of nitrate around neutrality. The most pronounced host‐species difference was found with β‐glucuronidase, which showed maximal activity at pH 6–0 in human faecal bacteria, while the rat caecal flora expressed greatest activity at pH 8–0. All three enzyme activities were associated with that fraction of rat caecal or human faecal material sedimented by centrifugation at 5000 g for 15 min, with little or no metabolism occurring in the 11000 g supernatant fluid. The results demonstrate that pH has a pronounced effect on the enzymic activity of bacterial preparations from

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb05112.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The extracellular xylanase activity of 15 actinomycete strains, representing a range of taxa, was examined. Enzyme production was correlated with growth in all cases and product analysis demonstrated that degradation was the result of endoxylanase activity. This was subject to end‐product inhibition, probably by xylobiose, but was not inhibited by cellobiose or monomeric sugars. Gel electrophoresis showed that up to six separate endoxylanases were produced but only one was identified in strains that exhibited poor activity. Activity against xylan was found to be specific in that no cross‐reactions with endoglucanase activity were detected. The xylan‐degrading systems of actinomycetes are clearly complex and non‐uniform, although there is some evidence of conservation withinStrep

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb05113.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY