The object of this work was to study the effect of rifampicin on the physiological state of Bacillus megaterium and Candida utilis in chemostat and batch cultures. When B. megaterium is cultivated in a medium containing 1 microgram of rifampicin per litre, its metabolism changes, the pool of free nucleotides rises, and the content of RNA drops in response to the specific action of the inhibitor. The modified state is observed throughout many generations. The action of the inhibitor is also non-specific: protein content falls and polyhydroxybutyric acid is accumulated. The morphology of B. megaterium cells changes: they become larger, their cell wall thickens, and the separation of cells from one another is complicated. At a high concentration (5 mg/l), rifampicin decelerates the growth of C. utilis and causes merely a minor non-specific inhibition.

Bacillus megaterium↗

PubMedDate not supplied

[Chemical composition and morphological changes in the cells in a chemostat Candida utilis culture inhibited by zinc ions].

The effect of zinc ions on the physiological state of Candida utilis VKM Y-1668 was studied during its chemostat cultivation. The concentration of zinc ions was maintained at a constant level. Zinc was found to inhibit the growth at a concentration of 300 mg/l. The cells were rapidly washed from the fermenter when zinc concentration was increased to 500 mg/l. Zinc uptake by the culture became greater when zinc concentration in the medium was gradually increased. If the yeast was cultivated in the presence of the inhibitor, the content of protein, RNA, DNA and polysaccharides fell while lipid content increased. Growth inhibition by zinc ions interfered with cell division; the cells could not separate from one another and formed catenae and conglomerates.

Candida↗

PubMedDate not supplied

[Sporulation and crystal formation in Bacillus thuringiensis during growth limitation via nutrient sources].

The object of the work was to study the effect of limiting concentrations of glucose, yeast extract, phosphorus, magnesium and potassium on the growth, spore formation and crystal formation in Bacillus thuringiensis subsp. galleriae. The deficiency of the above components was shown to interfere in no way with the processes of spore and crystal formation. However, the type of limiting substrate influenced the character of spore formation, the duration of different phases in the culture growth, the yield of spores and crystals, and their quality.

Bacillus thuringiensis↗

PubMedDate not supplied

[Variability of Bacillus thuringiensis under various growth conditions].

When a lysogenic culture of Bacillus thuringiensis subsp. galleriae 69-6 was grown under the batch conditions, 93-99% of cells in the population produced R-form colonies and ca. 1% yielded S-form colonies. The amount of spore-forming cells was 99% in R-variants and 8% in S-variants. The quantity of S-variants rose abruptly to 99% when the culture was grown under the chemostat conditions. The number of S-variants increased with the rate and the duration of growth. The process was influenced by growth-limiting factors. Temperate phage variants capable of host culture lysis on solid media (i.e. h-mutants) were not found under the conditions of batch cultivation. However, such phage particles (h-mutants) appeared under the conditions of chemostat. The titre of these phage particles reached 10(8), 10(7) and 10(4) particles per 1 ml at limitation with yeast extract, glucose and phosphorus, respectively. Under the conditions of chemostat, the particles behaved as temperate ones and their growth was not found. Irrespective of the limitation, the phage titre did not correlate with the ratio of R and S-forms in the population. When the growth was limited with phosphorus, the quantity of S-forms increased abruptly while the spontaneous induction of the phage was inhibited. The quantity of cells capable of spore formation decreased in the cultures isolated from the chemostat and grown on MPA: 69-80% of the cells in R-forms and merely 8% in S-forms.

Bacillus thuringiensis↗

PubMedDate not supplied

[Processes for culturing microorganisms].

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Bacteria↗