摘要:

OkaforN. IjiomaB. Oyolu, C. 1984. Studies on the microbiology of cassava retting for foo‐foo production.Journal of Applied Bacteriology56, 1–13.Five bacteria (Bacillus, Lactobacillus, Klebsiella, Leuconostoc, and Corynebacterium) and a yeast (Candidaspp.) were isolated from cassava being fermented for foo‐foo production. Retting of cassava was assessed by determining the weight required to crush cylindrical cassava pieces. A weight in excess of 2.5 kg was required to crush an unfermented peeled cassava cylinder 4 mm diameter and 4 cm long whereas a weight as small as 20 g could crush the same piece after retting. The organisms were studied for their ability to cause retting of sterile cassava pieces, alone or in various combinations. Retting did not occur unless either theBacillussp. or theCorynebacteriumsp. was present. Only these two organisms hydrolysed starch. The lactic acid bacteria lowered the pH of the fermenting medium although they did not bring about retting. The typical aroma of foo‐foo was produced, however, only when the lactic acid bacteria were present in the mixture. Only theCorynebacteriumsp., was, however, shown to produce pectinolytic enzymes and it is possible that theBacillussp. caused retting by disintegrating other cell components. The typical aroma of foo‐foo is disliked by some individuals and it seems possible that foo‐foo with a bland aroma, which will presumably be more acceptable to this group, can be produced by using organisms causing retting while excluding those forming

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb04691.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AllsopK.&SticklerD. J. 1984. The enumeration of Bacteroides fragilis group organisms from sewage and natural waters.Journal of Applied Bacteriology56, 15–24.A membrane filtration technique has been developed for the enumeration ofBacteroides fragilisgroup (BFG) organisms from sewage and natural waters. The method uses the agar medium of Wilkins and Chalgren supplemented with gentamicin. penicillin, aesculin and ferric ammonium citrate. Membrane filters with 0.22 μm pores were significantly more efficient than those with 0.45 μm pores in the isolation of BFG. A preliminary incubation period of 4 h at 30d̀C prior to 44 h at 37d̀C yielded significantly higher numbers of BFG than direct incubation at 37d̀C fo

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb04692.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

ShawB. G.&HardingCharmaigneD. 1984. A numerical taxonomic study of lactic acid bacteria from vacuum packed beef, pork, lamb and bacon.Journal of Applied Bacteriology56, 25–40.A numerical taxonomic study using 79 unit characters has been performed on 100 isolates of lactic acid bacteria from refrigerated vacuum‐packed beef, pork, lamb and bacon. Three clusters were observed at 78% S which contained all the strains apart from three unidentifiable streptobacteria, oneLeuconostoc, and one strain ofPediococcus pentosaceus. One cluster (III) consisted of only one strain ofLeuc. paramesenteroidesand six unidentifiable Leuconostoc strains. The two largest clusters (I and II) were both composed entirely of streptobacteria. Cluster I contained 31 strains (G + C content 33–2–36–9 moles %) which were not identifiable with any described species. Cluster II contained 57 strains (G + C content 40–7–43–7 moles %) which were provisionally identified withLactobacillus sake or Lact. bavaricusaccording to the lactic acid isomer produced. The division of nearly all the streptobacteria into two clearly defined clusters has resolved problems which have existed in the classification of lactic acid bacteria from vac

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb04693.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Prior, B.A. 1984. Role of micro‐organisms in biltong flavour development.Journal of Applied Bacteriology56, 41–45.When biltong, a dried salted meat product, is prepared from beef, micro‐organisms are able to proliferate freely and counts of 9.8 times 104to 3.8 times 107/g are observed. Treating the meat with four antibiotics before production of the biltong restricted microbial growth, yet a taste panel was unable to distinguish between biltong containing high and low numbers of micro‐organisms. No significant difference in the free amino acid and free fatty acid content of biltong; prepared with and without antibiotics was detected although there were significant increases in these compounds during biltong production. These results suggest that micro‐organisms are not involved in the development of biltong flavour and microbial inhibitors may thus be added to the meat as a preservative agent without affecting the development of the biltong flavour, taste

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb04694.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

LynchJ.M.&ClarkSarahJ. 1984. Ejects of microbial colonization of barley (Hordeum vulgareL.) roots on seedling growth.Journal of Applied Bacteriology56, 47–52.A range of micro‐organisms, particularly pseudomonads, was isolated from seed, rhizosphere soil and straw. Their colonization and effects on the growth of barley seedlings in gnotobiotic culture were studied. The colonization potentials of the different species were between 004 and 47 times 106viable cells/mg dry root. Some organisms stimulated root and shoot extension and dry matter production while others were inhibitory; these effects were not directly related to the colonization potenti

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb04695.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

TranterH.S.&Board, R.G. 1984. The influence of incubation temperature and pH on the antimicrobial properties of hen egg albumen.Journal of Applied Bacteriology56, 53–6.Gram positive bacteria, including lysozyme‐resistant strains, and yeasts were killed in hen egg albumen with or without iron at 30 of 39.5.dGC. The albumen was more toxic at 39.5.dGC than at 30d̀C for Gram negative bacteria. With the exceptions ofPseudomonas fluorescens, Acinetobactersp. andProteus vulgaris, iron caused the growth of Gram negative bacteria or protected them from being killed in hen albumen at 39.5.dGC. At this temperature, however, maximal growth of and glucose utilization byEscherichia coliC20 only occurred in albumen supplemented with growth factors, trace metals, additional nitrogen and sufficient iron to quench ovotransferrin. The bactericidal properties of albumen could be negated by changing its pH from 90 or above to 7.5 or below. At 39.5d̀C, enterochelin allowed growth ofE. coliin albumen at pH 7.9, but not at 9.4, whereas iron allowed growth at both pH v

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb04696.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

RossouwF.T.&RowburyR.J.1984. Effects of the resistance plasmid R124 on the level of the OmpF outer membrane protein and on the response ofEscherichia colito environmental agents.Journal of Applied Bacteriology,56, 63–79.The introduction of the F‐like resistance plasmid R124 into anompCmutant ofEscherichia coliK12 conferred altered sensitivity to a wide range of inhibitory agents. Sensitivity to ampicillin, chloramphenicol, ethionine, copper ions, deoxycholate, two fatty acids and colicins L and M was decreased by the plasmid. In contrast the plasmid‐bearingompCderivatives were more sensitive than the plasmid‐freeompCmutant to erythromycin, cetyltrimethylammonium bromide and phenol. Introduction of R124 into theompCstrain also decreased the level of the OmpF protein and some (but not all) of the changed sensitivities listed above clearly resulted from this outer membrane protein deficiency. The presence in theompCmutant of R124 (rather than the more efficient introduction of the plasmid into variants of theompCstrain) led to at least most of the changes described above because those tested were accentuated by the presence of a copy mutant of R124 and reversed by plasmid

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb04697.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

CzerkawskiJ.W., PiatkovaM.&Breckenridge, G. 1984. Microbial metabolism of 1,2‐propanediol studied by the Rumen. Simulation Technique (Rusitec).Journal of Applied Bacteriology,56, 81–94.A series of experiments with the Rumen Simulation Technique (Rusitec) showed that 1,2‐propanediol was metabolized efficiently by rumen micro‐organisms and that the main end‐products of fermentation were propionic and 2‐methylbutyric acids. ‘Propionaldehyde and n‐propanol were also formed as intermediate compounds.’ The effect of the diol on digestion of the basal diet appeared to be small with concentrate, or when the roughage was supplemented with additional nitrogen (urea). The decrease in the output of acetic and butyric acids was consistent with utilization of C2units for synthesis of 2‐methylbutyric acid. The fermentation of 1,2‐propanediol resulted in little or no increase in the output of additional microbial matter. The distribution of radioactivity from [1‐14C] 1,2‐propanediol confirmed that propionaldehyde andn‐propanol were the primary products of metabolism of the diol and that the end‐products were propionic and 2‐methylbutyric acids, with very little labelling of microbial matter. Between 2% and 3% of radioactivity was found in gases and surprisingly the specific radioactivity of methane was higher than that of carbon dioxide, particularly during the initial stages of incubation. Possible pathways in the degradation of 1,2‐propanediol by rumen micro‐organisms are suggested and discussed in relation to similar rea

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb04698.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Gorman, S.P. Scott, E.M. Hutchinson, E.P. 1984. Interaction of theBacillus subtilisspore protoplast, cortex, ion‐exchange and coatless forms with glutaraldehyde.Journal of Applied Bacteriology56, 95–102.Bacillus subtilisspores with altered ionic content were tested for their susceptibility to lysis with lysozyme or sodium nitrite following treatment with glutaraldehyde. The Ca‐form was more sensitive to glutaraldehyde (pH 4.0.and pH 7.9) than the untreated or H‐form. Removal of spore coat dramatically increased sensitivity of the spore to glutaraldehyde. Pretreatment of spores, the coats of which had been extensively removed, with glutaraldehyde (pH 7.9) reduced the rate of lysis by lysozyme and by sodium nitrite, whereas glutaraldehyde at pH 4.0.had little effect. Glutaraldehyde pretreatment (pH 4.0 and pH 7.9) reduced the amount of hexosamine released by lysozyme but not by nitrite from isolated cortical fragments. Spore protoplasts were more susceptible to 0.01% (w/v) glutaraldehyde at pH 4.0 and isolated spore coats adsorbed alkaline glutaraldehyde more rapidly. These results are discussed in terms of a possible mode of action of glutaraldehyde on the bacteria

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb04699.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Lloyd, D.H. 1984. Evaluation of a cup scrub technique for quantification of the microbial flora on bovine skin.Journal of Applied Bacteriology56, 103–107.A cup‐scrub technique devised for sampling the human skin surface microfiora was evaluated in cattle. Scrub samples from bovine skin contained clumps of squames and bacterial microcolonies which were progressively broken down by shaking. This was accelerated in the presence of ballotini beads but aggregations of bacteria were still present after prolonged agitation. Vigorous shaking, particularly with beads, decreased the viability of the bacteria and optimum viable counts were obtained after manual shaking for half a minute. Immersion in buffered detergent, wash and diluting fluids for up to 2 h promoted release of bacteria from micro‐colonies but decreased the viability of aerobic and anaerobic pleomorphic rods and aBacillusstrain. There was no significant effect on strains of Micrococcaceae. Prolonged exposure of bacteria from scrub samples to these fluids can thus lead to both quantitative and qualitative alterations in the counts: obtained, although these effects may be masked by the continuing release of bacteria from microcolonies. The cup‐scrub technique provides a convenient means of quantifying changes in the bovine skin microfiora but results obtained from different studies should only be compared if closely similar techniques a

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb04700.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY