Fatty acid and β-amino acid syntheses in strains ofBacillus subtilis producing iturinic antibiotics

Abstract

Iturinic antibiotics, produced by different strains ofBacillus subtilis, contain long-chain β-amino acids (β-AA). The regulation of the synthesis of fatty acids (FA) and β-AA was studied by modifying the culture medium. Addition of possible precursors, branched-chain α-amino acids, to the medium affected the FA and β-AA compositions. According to this, theB. subtilis strains can be divided into two groups. The first contains the producers of mycosubtilin and bacillomycin F which synthesize a high level ofiso C₁₆ chains; the second contains the producers of bacillomycin D, bacillomycin L and iturin which synthesize a high level ofn carbon chains.

The incorporation of radioactive sodium acetate into FA and β-AA showed rapid FA synthesis followed by a second synthetic step. Although the detailed mechanism has not yet been elucidated, this second step, corresponding to the β-AA synthesis, seemed to be a key step in determining the alkyl chain of β-AA.