Optimisation of nutritional requirements and process control parameters for the production of HA-2-91, a new tetraene polyene antibiotic.

HA-2-91, a new tetraene polyene antibiotic produced during submerged fermentation of Streptomyces arenae var ukrainiana. Optimisation of nutritional requirements and process control parameters were studied for higher productivity of HA-2-91 during fermentative production in shaken flasks using complex media. Experimental findings indicate that jowar starch (Sorghum vulgare) is the best carbon source while cornsteep liquor in combination with peanut meal are the best nitrogen sources. Exogenous addition of amino acids, divalent cations and fatty acids suppressed the productivity of HA-2-91. Incorporation of glucose into the production medium above 5% (w/v) results in inhibition of productivity of HA-2-91 which may be due to catabolite regulation. The concentration of phosphate ions above 10 ppm also showed similar suppression effect on the productivity of HA-2-91. However, ferrous ions at 100 ppm showed slight stimulatory effect on the production of HA-2-91. The optimum process control parameters for the production of HA-2-91 were found to be temperature, 28 degrees C; inoculum concentration from seed to production medium, 1% (v/v); pH and volume of production medium 6.5 and 100 ml respectively; and fermentation cycle time, 120 hours.

Effect of dissolved oxygen levels on biosynthesis of aureofungin by Streptoverticillium cinnamoneum var. terricola.

Biosynthesis of aureofungin by Streptoverticillium cinnamoneum var, terricola was found to be an oxygen dependent reaction. An accelerated rate of aureofungin production, along with a better yield coefficient were obtained under conditions of enhanced aeration during fermentation. A higher oxygen transfer rate was found to stimulate aureofungin A, and suppresses aureofungin B formation.