ISSN:
1432-072X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary 1. The effects of eighteen l-amino acids and two peptides, added individually to an otherwise autotrophic medium, on the growth of Thiobacillus thioparus, Thiobacillus neapolitanus and Thiobacillus thiooxidans were tested. Under these conditions, specific l-amino acids, which differed for each of the thiobacilli, inhibited growth. 2. All inhibitory effects were reversed, completely or in part, in the presence of non-inhibitory concentrations of casein hydrolysate. 3. l-tyrosine or l-tryptophane reversed the l-phenylalanine inhibition of T. thioparus and T. neapolitanus; l-serine inhibition of T. thiooxidans was partially reversed by l-threonine and completely by l-valine plus l-leucine; and l-valine inhibition of T. thiooxidans was similarly reversed by l-leucine or l-isoleucine. 4. In cell-free systems derived from T. thiooxidans, l-valine or l-isoleucine inhibited the activity of acetolactate-forming enzyme. Repression of synthesis of this enzyme by l-valine, l-isoleucine and l-leucine could not be demonstrated. 5. d-valine and d-isoleucine were also inhibitory to T. thioparus. The inhibition by d-valine was not reversed in the presence of any combination of the l-isomers of valine, isoleucine and leucine. 6. It is concluded that inhibition of growth of these three obligately chemolithotrophic thiobacilli by l-amino acids is due to amino acid imbalances that derange normal regulatory processes as also occurs in chemoorganotrophic bacteria.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00424911
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