Article Abstract:
The early part of the growth phase of Streptomyces griseus cells is the phase where the decision to produce streptomycin is made. S. griseus cells decide to produce or not to produce Sm during the early part of the vegetative or exponential growth phase (EGP), with the fixation of later production and differentiation possibly influenced by effector molecules only during this period. When the second EGP has begun, the commitment to produce Sm is irreversible, either by dilution into fresh medium or by effector molecules.
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Article Abstract:
A variation in the specific activities of the enzymes acetohydroxy acid synthase and isopropylmalate synthase of branched-chain amino acid biosynthesis in Streptomyces coelicolor was observed under different physiological and genetic conditions. Similar effects on the specific activities of both enzymes were observed when the branched-chain amino acids leucine, isoleucine and valine were supplied singly or in combination in batch culture in minimal media.
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Article Abstract:
At temperatures higher than 37 degrees centigrade (C), the activity of streptomycin biosynthesis promoter PstrB1 decreases. However the StrR-independent expression of PstrB1 is unaffected by an increase in temperature. Thus the inability of Streptomyces griseus to produce streptomycin at temperature higher than 37 degrees C is probably due to a change in StrR activity at high temperatures.
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