1887

Abstract

SUMMARY: The influence of casein hydrolysate, tryptophan, glucose, magnesium sulphate and different buffer solutions on the rate of multiplication of strain 168 was determined. Inoculum size was shown to influence the generation time and the increase in the mass of bacteria was found to be inversely proportional to the size of the inoculum. Bacillus subtilis 168 forms chains especially in minimal media. In complete media chains are formed by only a small proportion of the bacteria and sometimes not at all.A simple transformation method was used to follow the development of competence in cultures of 168 in media inoculated with different numbers of bacteria. The estimation of the number of transformants was subject to greater error than estimation of the viable count. This error in the estimation of the number of transformants is due mainly to the thread-like character of DNA, which is difficult to dilute accurately. The smaller the inoculum of bacteria, the shorter the time for the rise phase of competence. Optimal competence is reached when about 10 bacteria/ml. are inoculated into the medium. The rise phase of competence takes a shorter time than the decline phase.An equation was developed from which it is easy to calculate approximately the onset of the peak of competence. Precise determination of this peak can be achieved by controlling the density of the bacterial suspension.

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/content/journal/micro/10.1099/00221287-48-2-215
1967-08-01
2019-10-22
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http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-48-2-215
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