Optimization conditions of alkaline protease production by Streptomyces sp.H1 isolated from red sea coastal region in submerged culture

摘要

A potent alkaline protease producing strain characterized and identified as Streptomyces sp. H1 was isolated from soil around red sea shore. The enzyme was produced extracellulary in submerged culture revealed maximum level during early stationary phase. Alkaline protease showed the highest activity at incubation time, pH and inoculum size of 3 days, 9 and 8% respectively. Among different carbon sources beet molasses gave a maximum production followed by starch, sucrose and fructose. High yield of protease production was noticed with casein followed by peptone, yeast extract and ammonium sulphate. Furthermore, it was optimized with 7g/l NaCl resulted in higher level of protease. Optimization of the process parameters resulted in about 3.4 fold increase in the alkaline protease. Partial purification of the crude enzyme was achieved by fractional precipitation using ammonium sulfate at 50% saturation. Due to the maximum production of protease in the presence of cheaper substrate as beet molasses, stability at alkaline pH 9 and temperature up to 70 oC besides salt tolerance make the strain and its enzyme useful in different industrial applications.