ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02489.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.tb02490.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Mycological studies have been carried out on market samples of gari, a ready‐to‐use staple fermentation product of cassava (Manihot esculenta cranz). Commercial and industrial samples were analysed. The moisture contents of samples varied from 7% to 17% while the water activity (aw) varied from 0·52 to 0·85 and the pH of samples ranged from 3·9 to 7·26. Several fungi were isolated from the commercial samples while the industrial packaged samples were relatively mould‐free. Moulds isolated were mainlyAspergillusspp.,Penicilliumspp., and several Mucorales, e.g.Rhizopussp.,Syncephalastrumsp.,Mucorsp. andCir

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02491.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Plasmid analysis of over 120 strains ofClostridium perfringens, isolated during food‐poisoning incidents and from animal carcasses and food constituents with no association with food poisoning, showed the potential of plasmid profiling as a means of differentiating epidemiologically related strains. On average 65% of freshly isolated strains contained one or more plasmids which could be used in the analysis. Comparison of profiles of strains from unrelated sources or unrelated strains from the same source showed a particularly wide variety of plasmid profiles. Thus the possibility that epidemiologically‐unrelated strains might possess similar profiles appears to be very low in this organism. Analysis of serologically‐related strains from the same source revealed similar plasmid profiles in all the plasmid‐bearing strains examined. A high proportion (71%) of fresh and well‐characterized food‐poisoning strains possessed plasmids of 6·2 kb in size (compared with 19% of non‐food‐poisoning strains). The possible role of these plasmids is discussed, since the structural gene encoding the enterotoxin type A was not present on any of the plasmids in the food‐poison

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02492.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Lactobacillus sakeL13 produced hydrogen sulphide during growth at 0°C on vacuum‐packaged beef of normal pH (5·6–5·8) when the packaging films used had oxygen permeabilities as high as 200 ml/m2/24 h/atm (measured at 25°C and 98% relative humidity. No hydrogen sulphide was detected when the film permeability was 300 ml/m2/24 h/atm. Sulphmyoglobin was formed whenever hydrogen sulphide was present except when the film permeability was very low (1 ml of oxygen/m2/24 h/atm).Lactobacillus sakeL13 also produced hydrogen sulphide when grown on beef under anaerobic conditions at 5°C. When meat pH was high (6·4–6·6) hydrogen sulphide was first detected after incubation for 9 d. When 250 μg of glucose was added to each g of high pH meat, or when meat pH was normal (5·6–5·8), hydrogen sulphide was first detected after incubation for 18 d. The spoilage of beef by hydrogen sulphide‐producing lactobacilli is more rapid when the pH of the meat is high because high‐pH meat contains less glucose. Sulphmyoglobin formation and greening can be prevented by the use of packaging films of very lo

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02493.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

It was necessary to incubate theKlebsiella pneumoniaehaemolysin with erythrocytes at 37°C to produce the whole lytic action. The amount of attached klebolysin at 4°C increased as its concentration in the medium increased, until the erythrocyte surface was saturated. Treatment with 2‐mercaptoethanol was necessary to permit the adsorption; it was inhibited by low concentrations of cholesterol. Klebsolysin was immunogenic and its antiserum neutralized its own haemolytic effect and streptolysin O. Anti‐streptolysin serum also neutralized klebsolysin. Streptolysin O attachment to erythrocytes impeded the posterior klebolysin adsorption in the same way that klebsolysin adsorption interfered with streptolysin O attac

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02494.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The production and characteristics of a compound inProteus vulgarisG cultures which was capable of inhibitingVibrio parahaemolyticusand other food‐borne pathogens was investigated. Production was influenced by medium composition, pH and temperature but not by the extent of aeration. The compound was most inhibitory at the optimum temperature for growth ofV. parahaemolyticus.The inhibitor was most stable at pH 7·0 and inhibition occurred even after heating at 70°C for 30 min and after autoclaving. Ultrafiltration showed that the inhibitor had a molecular weight less than 1000. Thin layer chromatography of filtrates and subsequent peptidase digestion indicated that it was at least in part a peptide. The inhibitor purified by Sephadex G‐15 gel filtration had a calculated molecular weight of 731 and contained only six amino

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02495.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Thirty‐two strains ofBacillusspp. were examined in a multilocus enzyme study by agarose gel electrophoresis. The organisms wereBacillus thuringiensis(21 strains),B. cereus(8), including two of var.mycoides, andB. megaterium(3). Strains having similar enzyme variants were grouped into zymovars. A total of 10 of 11 enzyme loci studied were polymorphic and 27 zymovars were distinguished among the 32 strains. The results were subjected to numerical analysis, phenetic affinities and genetic distances between the strains were calculated. The numerical analysis was unable to differentiate betweenB. thuringiensisandB. cereus. Our results indicated that based on this multilocus enzyme study these zymovars should be considered as belonging to the same species. Amycoidesvariant ofB. cereuswas the most distinctive strain studied and clearly belonged to a separate species,B. mycoides.The technique also allowed for identification of contamination and mislabelling of strain

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02496.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The fimbriae of 50 strains of serotype Gallinarum and 35 strains of serotype Pullorum of the genusSalmonellawere compared with the type‐1 fimbriae of serotype Typhimurium strains by immune electron microscopy and dot blot hybridization tests with gene probes for type‐1 fimbriation in Typhimurium. The fimbriae of Gallinarum and Pullorum strains were coated with Typhimurium type‐1 fimbrial anti‐serum and probes hybridized strongly with DNA of Gallinarum and Pullorum strains under stringent conditions. Furthermore, when Typhimurium type‐1 fimbrial antiserum, that had been absorbed with fimbriate Gallinarum or Pullorum bacteria, was used in immune gold labelling experiments, it was shown that residual antibody recognized sites of possible adhesin incorporation at intervals along the length of Typhimurium type‐1 fimbriae. These findings suggest that the type‐2 fimbriae produced by all Gallinarum and Pullorum strains are non‐adhesive forms of adhesive, type‐1 fimbriae. This observation is of interest because type‐1 fimbriae have never been reported in naturally occurring strains of these two avia

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02497.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Epiphytic bacteria were compared with planktonic bacteria in two watercourses enriched with sewage works effluent. Colony‐forming units as a percentage of acridine orange direct counts were higher for epiphytic bacteria in one watercourse. The percentage of cells capable of intracellular reduction of 2‐(p‐iodophenyl)‐3‐(p‐nitrophenyl)‐5‐phenyl tetrazolium chloride (INT) to INT‐formazan was higher for epiphytic bacteria in both watercourses. The greater viability of epiphytic over planktonic bacteria was less evident, however, than in previously studied non‐enriched gravel pit ponds. This suggests that the greater availability of dissolved organic nutrients in the enriched watercourses reduced stress on

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02498.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY