Optimization of fermentation conditions of Streptomyces HA6 isolated from mangrove sediment

Strain HA6,which was isolated from mangrove sediments,showed strong antibacterial activity.16S rDNA gene analysis indicated that strain HA6 belongs to genus Streptomyces and shared highest 98.8% similarities with Streptomyces griseorubens.To improve its production of antibacterial substance,single factor experiment and orthogonal experiment were used to optimize the fermentation conditions considering the medium ingredients,inoculation concentration,ventilatory capacity and fermentation time.The results indicated that the optimum composition of fermentation medium can be consisted of malt extract 2.00 g,soluble starch 3.00 g,soybean powder 2.00 g,(NH4)2SO4 1.00 g,NaCl 3.00g,CaCO3 0.50 g,distilled water 100 cm3.The optimum fermentation conditions were with liquid volume 150 cm3 in 500 cm3 flask,inoculation concentration 8%,temperature 28℃,initial pH 7.5,rotationl speed 200 r/min and incubation time 5 d.