摘要:

SUMMARY:The action of various concentrations of nisin on the development of cells and spores from untreated and heated suspensions ofClostridium welchiiadded to gelatine has been investigated, using a tube colony count technique. The development of vegetative cells was prevented by the presence of 2 Reading Units (R.U.) of nisin/ml of the final culture medium, although the effective concentration may have been 6 R.U./ml. Approximately 40 R.U./ml prevented colony formation from spores. Gelatine containing nisin was dried. A considerable proportion of the activity of the antibiotic was still present after storage for 5 weeks.

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1959.tb04603.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

SUMMARY:Sodium benzylpenicillin, contaminated withBacillus subtilisspores by freeze‐drying a suspension of spores in an aqueous penicillin solution (c. 50% w/v), was exposed to gamma radiation and a 70‐tube dilution method was used to determine the surviving spores after various doses. The correlation coefficient between log10percentage survival and dose was −0.9523. The regression of the former on the latter was calculated and the decimal reduction dose found to be 20.2 × 104rads. The regression and the decimal reduction dose were similar to those obtained when suspensions of spores in distilled water were irra

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1959.tb04604.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

SUMMARY:Forty mould species, 30 of which were from the generaAspergillus, Penicillium, FusariumandMucor, were examined for their ability to utilize the lactose in whey and to produce fat in the mycelium in stationary cultures.In terms of lactose consumed and weight of mycelial felt produced the most promising species wereA. ustus, P. frequentans, P. oxalicumandP. notatum.The first three of these warrant further study as fat producers.

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1959.tb04605.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

SUMMARY:A Gram‐positive coccus with the properties typical of pediococci produced a ropy, viscous growth in malt wort. Nutritional studies in the media of Dunnet al.(1947) showed pantothenic acid to be required by the organism but growth occurred in the complete medium only when a trace of malt wort was present. Seven other vitamins tested were not necessary for growth.In a medium consisting of mineral salts, glucose and alcoholic extracts of peptone and yeast autolysate the organism grew well and the viscosity of the medium increased. Higher viscosities were attained when the buffering capacity of the medium was increased either by raising the concentrations of the alcoholic extracts or by adding sodium acetate. The material responsible for the viscosity was produced in small amounts only and appeared to be a mucopolysaccharide. The only sugar obtained on hydrolysis of this material was glucose.Fructose, maltose, sucrose and raffinose were all fermented by the organism but only in media containing maltose was the increase in viscosity comparable with that attained in a glucose‐containing med

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1959.tb04606.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

SUMMARY:A series of 825 cultures of coli‐aerogenes bacteria isolated at 30° and a series of 735 cultures isolated at 37° from 645 samples of farm water supplies were classified according to the recommendations of the Coliform Sub‐Committee of the Society for Applied Bacteriology (Report, 1949).Klebsiellaconstituted 50% of the cultures isolated at 30°, whereasEscherichia coliI was the dominant type, forming 57%, among the cultures isolated at 37°. It would thus appear that isolation at 30° is as selective forKlebsiellaas isolation at 37° is forEscherichia. Coli‐aerogenes organisms, mainly 37° negative strains ofCitrobacter freundiiI andK. cloacae, were found in waters of high sanitary quality derived from protected springs and wells; but the coli‐aerogenes microflora of polluted water was dominated byE. coliI, which formed 43% of the isolates at 30° and 76% of those at 37°. The results for a series of fortnightly samples from 11 farm water supplies showed a marked seasonal variation in the incidence of different types isolated at 30°;E. coliI formed a higher proportion in summer than in winter, while 37° negative strains ofKlebsiellaandCitrobacterformed a higher proportion in win

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1959.tb04607.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

SUMMARY:The results obtained during the examination of 2,310 advisory rinses of farm dairy equipment by means of colony count on Yeastrel milk agar at 30°, coli‐aerogenes test at 30° and milk spoilage organisms (MSO) test at 22°, are discussed in relation to attainment of proposed satisfactory colony count levels. A much higher proportion of rinses of milking machine clusters gave unsatisfactory results than those of metal equipment. The MSO test (3 days, 22°) was a more sensitive indicator of the presence of milk spoilage organisms than the coli‐aerogenes test, and is recommended for routine use. Results for milking machine clusters sterilized with steam were much better than those for clusters claimed to have been cleansed by chemical

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1959.tb04608.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

SUMMARY:Butter made on farms and at creameries was examined microbiologically within 24 hr of production. The overall care exercised in the manufacture of the butter was reflected in the results obtained with the various tests used. Colony counts of psychrophiles, coli‐aerogenes organisms, and yeasts and moulds were the most useful and economical tests for providing information on the standard of hygiene during manufacture, and they gave some indication of the potential keeping quality of the butter. The following satisfactory levels are recommended for creamery butter: psychrophiles<103/g, coli‐aerogenes organisms<10/g and yeasts and moulds<5

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1959.tb04609.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

SUMMARY:From various chilled meats, twenty‐eight strains of coli‐aerogenes bacteria and oneAeromonaswere isolated which grew well at +1±5° and some at −1±5°. The optimum growth temperature for most of these strains was nearer 37° than 30°. Nine strains (including theAeromonas) fermented lactose rapidly, the remainder slowly or not at all. All the strains which fermented lactose rapidly with the production of gas gave positive presumptive coli‐aerogenes tests in MacConkey's broth at 30°, but only five were positive at 37°; none was positive at 44°. Because such organisms can attain populations of millions/cm2, they could confuse the interpretation of presumptive coli‐aerogenes tests ma

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1959.tb04610.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

SUMMARY:A method is described for testing the self‐sterilizing activity of surfaces coated with paints containing bactericidal agents. The most active coating consisted of 10% (w/w) Cetavlon dissolved directly in urea‐formaldehyde:alkyd resin. The recovery of viable organisms from such surfaces infected withStreptococcus faecalis, Staphylococcus aureus, Aerobacter aerogenesandChromobacterium prodigiosumwas less than 10% of that from painted control surfaces after exposure for 1 hr at atmospheric relative humidity of 70% and temperature of 20°.Bacillus subtilisspores were not affected until they became heat‐sensitive. The self‐sterilizing activity was markedly diminished at 40% r.h. and the inclusion of blood in the deposited bacterial particle was then completely protective. Repeated washing in water with gentle rubbing quickly inactivated Cetavlon pai

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1959.tb04611.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

SUMMARY:The cleaning efficiency of hosing wooden market fish boxes with cold water, the usual commercial practice, was very low, even when high pressure jets were used. After washing, the internal surfaces could still carry up to 20 × 106bacteria/cm2. Even prolonged steaming failed to sterilize the surfaces. Coryneform organisms accounted for over 50% of the total bacterial flora, although these have usually been reported as present in only low proportions on both fresh and spoiling fish. The major subsidiary groups were species ofAchromobacterandPseudomonas, constituting about 18% and 14% of the population respectively. A few micrococci and flavobacteria were also present.The conditions of counting, i.e. whether roll tubes or Petri dishes were used, whether incubation was at 0°, 20° or 37°, and whether the media were based on sea or tap water, could markedly influence both the magnitude of the count and the proportions of the different types of bacteria which could be isola

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1959.tb04612.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY