ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02477.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

A single oral dose of fusarenon‐X (F‐X), a trichothecene mycotoxin, resulted in abnormal microflora in the jejunum in ICR mice and Wistar rats with some differences in dose response between the species. In the acute phase, enterobacteria, streptococci,Clostridium perfringensand bacteroides showed remarkably increased counts in the jejunum of mice and rats dosed with F‐X while lactobacilli showed a decrease in count. F‐X brought an invasion ofPseudomonas aeruginosainto the livers, lungs, kidneys and spleens of ICR mice. Changes in the jejunal microflora appeared after 7 h in ICR mice and after 24 h in Wistar rats after a single oral dose of F‐X of 7–5 and 4–0 mg/kg b.w., respectively, and the microflora returned to its normal state at 72 h in mice and 96 h in rats. The changes of intestinal microflora were followed by alterations in the growth curves of both animal species. The pH in the glandular stomach was also greatly enhanced before changes in the jejunal microflora. Acute F‐X intoxication may be an involved manifestation of essential cytotoxicity of F‐X mycotoxin alone and secondary bacterial overgr

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02478.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The β‐glucosidase ofHanseniaspora vineaewas purified by ion‐exchange chromatography and gel filtration. Its molecular weight was 295000 PT 15000, its optimum pH was between 6 and 6–5, and its optimum temperature was 55°C. The enzyme was active against different soluble glucosides with β(1–2), β(1–3), β(1–4), β(1–6) and even aP(1–4) configurations. A glucosyltransferase activity appeared in the presence of ethanol. The enzyme was constitutive but its synthesis was

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02479.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Volatile compounds produced byPseudomonas fragiand mixed, natural floras on beef of normal pH (5–5–5–8; glucose<1500 μg/g) and high pH (6–3–6–8; glucose<10 μg/g) included a range of alkyl esters and a number of sulphur‐containing compounds including dimethylsulphide but not hydrogen sulphide. Production of the last was a property common to the other Gram‐negative organisms tested viz.Hafnia alvei, Enterobacter agglomerans, Serratia liquefaciens, Alteromonas putrefaciensandAeromonas hydrophila, all of which produced similar off‐odours and, with the exception ofE. agglomerans, ‘greening’on high pH meat.Serratia liquefaciensalso produced greening of normal pH meat. Acetoin and diacetyl were major end products ofBrochothrix thermosphactabut the related 2,3‐butanediol was formed only on normal pH meat. The Enterobacteriaceae produced the same compounds but only on normal pH meat and together withBr. thermosphactawere probable sources of these compounds and of the free and esterified branched‐chain alcohols detected in the nat

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02480.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Streptococcus sanguis12 and a naturally occurring mutant, 12 na, were screened for their ultrastructure and adhesive propertiesin vitro.Negative staining showed thatStrep. sanguis12 carried three types of surface structure. The majority of cells carried long fibrils that in different batches ranged in length from 80 to 207 nm, and shorter fibrils which were 51mD0 PT 15mD7 nm long. Both types of fibrils were primarily located at the poles of the cells. Occasionally cells were seen that carried fimbriae, which are structurally distinct from fibrils, and were 3mD4 nm wide and<1mD μm long. Strain 12 na carried no detectable surface structures. Ruthenium red staining revealed that both strains carried a loose, amorphous, extracellular polysaccharide layer attached to the cell wall.Streptococcus sanguis12 na was 83% less adhesive than strain 12 in a saliva‐coated hydroxyapatite assay, and 50% less adhesive in a buccal epithelial cell adhesion assay. In contrast, strain 12 na was more sensitive to aggregation by parotid saliva than strain 12, and both strains were equally aggregated by whole saliva. The cell surface hydrophobicity of the two strains was similar. Extraction of surface proteins by sodium lauroyl‐sarcosinate followed by sodium dodecylsulphate polyacrylamide gel electrophoresis demonstrated thatStrep. sanguis12 expressed more high mol.wt proteins on its surface than strain 12 na. Using immunogold labelling, the fibrils of strain 12 labelled well with antiserum directed against the long fibrils, but so did the cell surfaces of bothStrep. sanguis12 and 12 na. High molecular weight proteins and cell surface fibrils may be associated with adhesion in this st

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02481.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

A new spectrophotometric technique for evaluation of early growth in liquid culture ofMycoplasma mycoidessubsp.caprihas been developed. As turbidity does not appear until after incubation to 18 h the method utilizes the change in absorbance of the medium at 550 nm to monitor growth. The change in absorbance of the medium (which contains phenol red) occurs when the pH changes due to microbial growth. For measurement of growth at later stages when turbidity is proportional to number of colony forming units, two other wavelengths (450 nm and 700 nm) have been suggested.

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02482.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

About 34% of the strains ofYersinia enterocoliticaisolated from raw milk were found to produce lecithinase. A selected strain produced phospholipase C at 22°C and 37°C; production was optimum at 37°C in the stationary phase (14–16 h). A decrease in phospholipase C activity at various storage temperatures (—5°C, 4°C, 37°C) was also observed, although the enzyme was active over a wide range of temperature (5–65°C) and pH (3mD5–7mD5). The phospholipase C was partially purified by ammonium sulphate precipitation and Sephadex column chromatography, and

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02483.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

An assay was developed for detecting β‐galactofuranosidase produced byPenicilliumandAspergillusspp. The substrate for the assay, 4‐nitrophenyl β‐D‐galactofura‐noside, was synthesized from penta‐O‐acetyl‐β‐D‐galactofuranose and 4‐nitrophenol by a tin chloride catalyzed reaction followed by O‐deacetylation.Aspergillusspp. produced only small quantities of β‐galactofuranosidase during 30 d at 25°C. Only the biverticillatePenicilliumspp. (P. funiculosum, P. islandicum, P. rubrumandP. tardum) produced substantial β‐galactofuranosidase after 1–4 weeks at 25°C. No extracellular antigens of these fourPenicilliumspp. could be detected in culture filtrates by the sandwich ELISA technique when antibodies to the extracellular β‐galactofuranoside‐containing polysaccharide antigen ofP. digitatumwas used. Antigens to all otherPenicilliumandAspergillusspp. were e

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02484.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

A simple, defined synthetic medium has been developed for the growth of a toxic‐shock‐syndrome‐associatedStaphylococcus aureusstrain (FRI 1187) in continuous culture, which gives a high growth yield and assayable amounts of acid phosphatase, haemolytic activity, hyaluronate lyase and toxic‐shock‐syndrome toxin‐1. It consists of multiple ions, ammonium sulphate, glucose, cystine, aspartate, glutamate, arginine, glycine, proline, nicotinic acid a

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02485.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The effects of freezing rate, suspending fluid and age of culture on the ability of four strains ofCampylobacter pylorito survive and recover from freeze‐drying were examined. Freeze‐drying by standard procedures generally resulted in an overall loss in viability of between 3 and 7 log units. The exact cause of poor recovery byC. pyloriwas not established but strain differences were detected, with NCTC 11637 (type strain) surviving better than NCTC 11638 and NCTC 11639. Recovery of the poorest growing strain (NE 26695) was notably more erratic. The largest loss in viability occurred at the primary drying stage. Losses resulting from freezing and secondary drying were less marked and the rate of freezing had only a marginal effect on recovery. Nineteen different freeze‐drying suspending fluids were investigated. Overall the best recovery results were obtained with 5% inositol‐broth (or horse serum) plus 25% glucose, at pH 7.0, in which loss of viability was typically about 4 log units. Other factors, such as age of culture and number of viable bacteria in the before‐dry suspension, did not have a significant effect on survival. We conclude from these results thatC. pylorican survive freeze‐drying, albeit in small numbers, but the degree of recovery is apparently largely strai

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb02486.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY