摘要:

SUMMARY:Cultures grown at 25° under an atmosphere of CO2in a medium containing maltose, inorganic salts and ethanolic extracts of peptone and yeast autolysate produced a polysaccharide, which was isolated and purified. Examination by a variety of chemical and biological methods indicated that it was a dextran of low molecular weight

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00172.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SUMMARY:A modification of the dulcitol‐lactose‐iron medium of Taylor&Silliker (1958) is proposed. It contains sucrose as well as lactose to aid in detecting slow lactose fermenters and gives simultaneously tests for urea hydrolysis and H2S production. The latter reaction is kept apart from the carbohydrate fermentations and the urea hydrolysis. The surface growth can be used in a test for the deamination of phenylalanine to phenylpyruvic a

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00173.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SUMMARY:An investigation of the effect of various sanitizers, including kinds containing hypo‐chlorite, formaldehyde and quaternary ammonium compounds, alone and with detergents, and of a nonionic detergent alone, on the cleanability by various methods of commercial wooden fish boxes, showed that no major reductions in viable counts greater than 99·9% could be expected; this was due presumably to the high degree of contamination of the box and the porous nature of the wood. Of the materials investigated, hypochlorite solutions containing not less than 1,000 p/m of free chlorine and the quaternary ammonium compounds in 0·1–1% concentrations were most satisfactory. The implications of these investigations, to the fish industry in particular and to the cleanability of wooden surfaces in general, are disc

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00174.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00175.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SUMMARY:During the steam sterilization of dressings some degree of superheating occurs. With dressings normally hydrated, that is with about 5% moisture content, the small degree of superheating which occurs is unlikely to be of consequence; but if dressings contain less than 1% of moisture before sterilization, a significant degree of superheating may occur. The use of drums is neither an advantage nor a disadvantage in regulating superheating, which occurs to the same degree whether the air is removed initially by vacuum pump or by downward displacement. The use of a high initial vacuum does not increase the risk of superheating.

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00176.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SUMMARY:A statistical experiment has shown that no significant proportion of the errors of determination of bacterial populations by the surface drop method could be attributed to the dropping technique employed. With both pure and mixed cultures the numbers of colonies/drop followed a Poisson distribution very closely.It is suggested that in order to determine bacterial populations at a consistent level of accuracy a constant number of colonies should be counted rather than a constant number of drops. Whenever it is justified, the confidence limits for the results of counts should be quoted.

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00177.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SUMMARY:Of 391 Gram‐negative bacteria isolated from chicken meat spoiled at a low temperature and classified by the commonly used methods, 156 were considered to bePseudomonasand 188Achromobacter, and 47 others belonged to the coli‐aerogenes group or remained unclassified. A test for the production of alkaline conditions in an arginine medium incubated under a vaseline seal gave positive results for 155 of thePseudomonasisolates, and negative results for 1Pseudomonasand all the 188Achromobacterstrains. When named strains from culture collections were tested under these conditions, 63Pseudomonasstrains produced alkalinity while two plant pathogenicPseudomonasspecies and two non‐pigmented strains did not. These last two, which produced no acid from glucose, could not be regarded as typicalPseudomonas.All theAchromobacterstrains gave negative results, as did fourAlcaligenes, but one species,Alcaligenes bookeri, produced slightly alkaline conditions. One strain ofChromobacteriumand three ofVibriowere also positive. These could be distinguished fromPseudomonasby their metabolism of gl

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00178.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SUMMARY:Yeasts tend to dissociate into mixtures of cell types with different powers of sporulation; hence single cell isolates are recommended for sporulation studies. The ability of yeasts to produce 4‐spored asci can be improved by single cell selection. Cells from actively fermenting cultures sporulate much better than those grown under aerobic conditions. Sporulating ability depends on fermentation ‘age’, reaching a maximum when 85–90% of the CO2has been evolved. Carbon dioxide assimilation in the presporulation phase appears essential for maximal sporulation, but complete anaerobiosis in this phase is detrimental to sporulating ability. Malt wort cultures of a baker's yeast have given remarkably constant figures, in successive tests, for sporulation; but some batches of wort have an adverse effect on sporulating ability. The same yeast, grown on Lodder‐Rij's synthetic medium containing 4 or 8% (w/v) of glucose, is capable of 80% sporulation (proportion of cells forming asci) on sodium acetate agar, comparable to that obtainable with malt wort cultures. Sporulation is depressed by excess storage of fat, while storage of glycogen does not affect sporulatin

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00179.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SUMMARY:A series of co‐operative experiments was conducted to compare the bacterial colony counts of soil obtained by workers in different laboratories, using soil extract agar and other media for the determinations.In the earlier experiments it was not possible to obtain a reasonable degree of reproducibility of results between laboratories even when the plating technique was carefully prescribed. By modification and more rigid standardization of the technique closer agreement was obtained in subsequent experiments. It is suggested that when co‐operative investigations are contemplated the participating laboratories should check their technique by the examination of ‘control’ soils.No evidence could be obtained to support the suggestion that higher colony counts are obtained by the use of soil extract media containing extract prepared from the same soil as the sample tested. The source appears to be immaterial so long as the soil for extract preparation is not of extreme type and has been well manured and cul

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00180.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SUMMARY:A filamentous mould was cultured by the continuous flow method in which medium is supplied at a constant rate and the culture volume is kept constant. Flow rates up to 0·1 culture volumes/hr were used. The mycelial dry weight concentration and the yield of mycelium/g of carbon source used were equal to or slightly greater than the maximum obtained in batch culture. With glucose concentrations up to 80 g/1. at a flow rate of 0·05 culture volumes/hr, about 45% of the substrate carbon was converted into mycelial carbon and the remainder oxidized to CO2.With unlimited amounts of all nutrients available growth of the mould followed the exponential law, as does bacterial growth, and therefore the mould had a constant doubling time.The oxygen demand of the mould as function of growth rate was determined.Conditions were found under which the rate of penicillin production/g of mycelium remained at its maximum value for 1000 h

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00181.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY