RESUMO
Effect of various fermentation media, carbon sources, nitrogen sources, phosphate concentration and culture requirements includes inoculum levels and age were determined on gentamicin production and biomass dry weight production for Micromonospora echinospora, a gentamicin producing strain. Of the substrates tested, starch as a sole carbon source promoted maximal gentamicin production, while maltose promoted maximal growth. Yeast extract as a sole nitrogen source promoted maximal growth, while soyabean meal for gentamicin production. Increasing phosphate concentration enhanced gentamicin production and observed optimum production at 1.2 g/1 (6% v/v) of phosphate having 72 h old inoculum in the medium. Highest gentamicin production was obtained after cultivation with shaking for 120 h in a medium containing starch 0.75% (w/v), soyabean meal 0.5%, K2HPO4 0.12%, CaCO3 0.4%, FeSO4 0.003% and CoCl2 0.0001%. The gentamicin production was 1.2-fold in this medium as compared to basal medium.