摘要:

SUMMARY:The rates of growth of bacteria onHevealatex systems in the presence and absence of ammonia have been derived from colony count data obtained on a modified Kligler's iron agar medium. For fresh latex, ammoniated field latex, and ammoniated latex concentrate, variations in the bacterial populations encountered are given for a period of about one year's testing, with some data on commercial samples of latex concentrate. Field latex at routine collection contained about 8 × 106bacteria/ml. This could be reduced by 62% by the use of sterile tapping cups. In the routine latex, the mixed population grew logarithmically after a lag phase of 2·1/2–3 hr. In clean latex the lag phase was extended to 4 hr. On ammoniation to 0.3% (w/w), the population was reduced over about 2 hr, but subsequently logarithmic growth recurred, without a lag phase. On concentration and further ammoniation to 0·7% (w/w), the count dropped still further, levels of 10/ml or less being achieved in clean conditions, but very slow logarithmic growth again occurred with a lag phase precedin

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1958.tb00131.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SUMMARY:The growth of a streptomycin resistant strain ofEscherichia coliI in MacConkey's broth at 37° or 42° was not inhibited by water organisms of the generaMicrococcus, Proteus, AchromobacterandPseudomonas, but the presence of large numbers of other members of the coli‐aerogenes group resulted in retardation or inhibition of its gro

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1958.tb00132.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SUMMARY:Suspensions ofEscherichia coliI, consisting of washed cells suspended in a phosphate buffer solution, maintained a higher viability and resistance to phenol than suspensions either of unwashed cells or of washed cells suspended in water. When stored for 5 weeks at room temperature, variations in their extinction times on exposure to aqueous phenol solutions were not significantly greater than variations with suspensions freshly prepared for each determination. Loss of resistance of a stored suspension to phenol, roxenol, lysol and potassium laurate was roughly parallel. Conditions of culture of the bacteria influenced the survival of suspensions, but the results indicated that pronounced differences may only be found in suspensions prepared from young cultures. The use of stored suspensions in the routine evaluation of bactericides is recommended.

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1958.tb00133.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SUMMARY:A quantitative study of the growth and carbohydrate metabolism ofAerobacter aerogenesin continuous culture with particular reference to 2:3‐butanediol production is described. The effects of varying dilution rate, oxygen uptake rate, pH value, temperature and CO2pressure were studied.The optimum pH value was 5·0°6·0. The optimum temperature was 35–37° with a dilution rate of 0·2 hr−1. The rate of sugar metabolism was decreased by raising the CO2pressure.In continuous culture the maximum diol output rate/1. of working volume exceeded the greatest rate reported for batch culture by a factor of three. The maximum diol concentration and yield as a percentage of the theoretical maximum were lower in continuous culture than in batch culture. Reasons for this are given.Some variants of the parent organism were found in continuous cultures but they caused no change in the yield of butanediol. There was no sign of loss of butanediol‐producing ability by any of the cultures, some of which were maintained for 2,000 hr. For the first few generations the rate of production of butanediol actual

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1958.tb00134.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SUMMARY:The maximum possible oxygen solution rates in bacterial cultures with different aeration conditions were appreciably less (0·5°0·7 times) than those in a sodium sulphite solution containing a copper catalyst under the same aeration conditions. Knowledge of the relationship between the maximum oxygen solution rates in a culture and the sulphite solution enables one to predict from the sulphite measurements the aeration conditions required to satisfy the oxygen demand of a cultu

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1958.tb00135.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SUMMARY:Inhibition of foaming in a continuous culture of bacteria has been studied. At first, foaming was inhibited by the addition of antifoam to the culture only when a foam layer was present. When the antifoam was added in this way foaming often became intense and antifoam additions had to be more and more frequent. In a preferred method the antifoam was added at regular intervals which were sufficiently short to inhibit foaming completely throughout the intervening periods. This method required less antifoam than the other. The effects of foaming in cultures, its causes, and allied problems are discussed.

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1958.tb00136.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SUMMARY:For routine purposes where a large number of tests is involved the dropping pipette technique has many advantages over other methods of determining the colony count. However, glass pipettes are fragile and much time and labour have to be used in making and calibrating replacements. A robust platinum tube dropping pipette has been found very satisfactory. No difficulty was experienced in obtaining complete sterility of the pipettes in the technique described, and reproducibility of drop size was good.

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1958.tb00137.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SUMMARY:Following the accidental discovery and subsequent confirmation of an 80% loss of viability in a suspension ofEscherichia coliwhen the ionic environment was changed from phosphate buffer to Ringer's solution, and of similar losses after changes in the reverse direction, the behaviour of other organisms was studied.Clostridium butyricum, Streptococcus lactis, Escherichia coli, andMicrococcus candidusgave positive results,Mycobacterium smegrmatisand a brewer's yeast did not. The survey included variations in the conditions, mostly withE. coli.Minor constituents of the solutions or alteration of their pH modified the effect, e.g. that of 1% NaCl in place of Ringer's solution or of pH 8·0 instead of the usual pH 7·2, was quite different. Also, the addition of glucose, sodium thioglycollate, or methylene blue diminished it, with one exception in the case of glucose.Mic. candidusresponded if the solutions were chilled, but not at room temperature. With electrolyte concentrations below about 0·02 M there was no effect. Various other changes of anions were effective, as also was change from a univalent to a bivalent cation. A second treatment, following the necessary intermediate reverse change which had no effect, caused another smaller mortality. This reduced sensitivity gave a diminished loss which persisted through many subsequent subculturin

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1958.tb00138.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SUMMARY:A reproducible flame speetrophotometric method for the determination of the potassium uptake ofLactobacilius acidophilusis described. The potassium uptake curve was characteristic and had a coefficient of variation between replicate samples at peak uptake of approximately 2%. Two general applications of the technique have been demonstrated: the evaluation of the toxicity of an inhibitory substance (fluoride as sodium fluoride), and determination of the effect of the interaction ofL. acidophilusandL. caseiin a mixed culture.

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1958.tb00139.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SUMMARY:Dehydrogenase activities have been determined of washed suspensions ofEscherichia coliprepared from cultures grown in a synthetic medium, and in the same medium supplemented with yeast extract, under conditions of controlled aeration. This supplementation resulted in increased activity of enzymes attackingL(+)‐alanine,DL‐serine, formate and succinate, no apparent change in activity of enzymes attackingL(+)‐gmlumate andD(—)‐ribose, and decreased action onD(+)‐glucose, mannitol and lactate. The results are discussed in the light of present knowledge of the metabolis

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1958.tb00140.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY