GENETIC-MAPPING OF BFMA MUTATION CAUSING FATTY-ACID DEFICIENCY IN BACILLUS-SUBTILIS

Bacillus subtilis strain 626, defective in the bfmA gene, is a derivative of B. subtilis strain 168 and requires branched short-chain carboxylic acids for growth. Branched-chain 2-keto acid decarboxylase activity and fatty acid synthesis in B. subtilis strain 626 were 14 and 7%, respectively, of their levels in strain 626-2R, a spontaneously reverted strain. These results indicate that the bfmA mutation is in either the branched-chain 2-keto acid decarboxylase gene itself or its controlling gene. Thus, primer synthesis from the 2-keto acid substrate in strain 626 is defective, causing a deficiency in fatty acid synthesis. A bfmA mutation was transferred to a suitable genetic background and analysed. The bfmA strain, CAC1, was competent and motile, and required 50 muM CaCl2 or 5 muM FeCl3 for growth on glucose minimal agar plates. The bfmA gene was mapped between glyC (320-degrees) and ctrA (325-degrees) and estimated to be at 320-degrees by protoplast fusion and PBS1 phage transduction.