title: Enhancement of bacitracin biosynthesis by branched-chain amino acids in a regulatory mutant of Bacillus licheniformis.
abstract: DL-4-Azaleucine-resistant mutant of Bacillus licheniformis azlr-1 isolated after N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis, was a better bacitracin producer than the parent strain. In the minimal medium, the antibiotic biosynthesis was 4 times higher in the mutant than in the parent strain and less dependent on L-leucine addition. In the complex fermentation medium, the yield was 18-20% higher in the mutant strain. Transaminase B activity measured in the crude extract revealed that the branched-chain amino acid biosynthetic enzymes were 5-10 times derepressed supplying bacitracin synthetase with enhanced quantity of isoleucine and leucine, the building units of bacitracin molecule.
mesh_terms: D000597:Amino Acids, Branched-Chain / Q000378:metabolism*; D001407:Bacillus / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D001414:Bacitracin / Q000096:biosynthesis*; D005798:Genes, Bacterial; D005809:Genes, Regulator; D007532:Isoleucine / Q000378:metabolism; D007930:Leucine / Q000378:metabolism; D009154:Mutation; D000637:Transaminases / Q000032:analysis / Q000378:metabolism; D014633:Valine / Q000378:metabolism
chemical_list: D000597:Amino Acids, Branched-Chain; D007532:Isoleucine; D001414:Bacitracin; D000637:Transaminases; C019798:branched-chain-amino-acid transaminase; D007930:Leucine; D014633:Valine