EFFECTS OF CULTIVATION MEDIUM COMPONENTS ON THE ACCUMULATION OF BACILLAR RIBONUCLEASES IN THE CULTURE LIQUID OF ESCHERICHIA-COLI RECOMBINANT STRAINS

The effect of the concentrations of peptone, yeast extract, and inorga nic phosphate on the expression of genes of extracellular ribonuclease s from Bacillus intermedius 7P (binase) and Bacillus amyloliquefaciens H2 (barnase) was studied in Escherichia coli cells transformed with p lasmids containing the structural genes of binase or barnase under the control of their own or synthetic regulatory region or the structural binase gene under the control of the regulatory regions of the genes of barnase or Bacillus pumilus RNase. Inorganic phosphate inhibited th e expression of the binase gene under the control of its own regulator y region or the regulatory region of the RNase Bp gene. In all other c ases, inorganic phosphate produced no effect on the synthesis of RNase s by E. coli cells. This difference in the effects of phosphate may be due to the presence of a nucleotide sequence similar to the E. coli P ho box in the promoters of the binase and RNase Bp genes and the absen ce of this sequence in the barnase gene promoter. It was shown that hi gh peptone and yeast extract concentrations in the cultivation medium are required for good growth of the recombinant E. coli strains and th e biosynthesis of RNases.