OPTIMIZATION OF CULTURAL CONDITIONS FOR HYDROXAMATE TYPE OF SIDEROPHORE PRODUCTION BY AZOTOBACTER-CHROOCOCCUM

Three soil isolates and four analogue resistant mutants of Azotobacter chroococcum were tested for hydroxamate production in iron limited modified Burk medium. Maximum hydroxamate was observed in a soil isolate 111 followed by analogue resistant mutant, Mac 68. Optimization of growth conditions for hydroxamate production was carried out using both, 111 and Mac 68. Hydroxamate production was more pronounced in B6 medium than in modified Burk medium under shake culture conditions with carbon sources like mannitol and sorbitol. Addition of nitrilotriacetic acid and trace elements caused decreased hydroxamate production in B6 medium. Increased growth and decreased hydroxamate production was observed in B6 medium containing iron.