Studies on Optimization of Amylase Production by Streptomyces cheonanensis VUK-A Isolated from Mangrove Habitats

Aims: To optimize the cultural parameters for enhanced amylase production by Streptomyces cheonanensis VUK-A.

Place and Duration of the Study: Coringa mangrove ecosystem of Andhra Pradesh, India, between June 2012 and July 2013.

Methodology: About 20 actinobacterial strains were isolated and subjected to primary screening for amylase production. The primary screening was carried out by inoculating the strains on Inorganic salts starch agar medium. The amylase assay was done by using the procedure described by Bernfield. The reaction mixture containing 1 ml of starch solution (10 mg/ml) and 1 ml of enzyme extract was incubated at room temperature for 15 min and the level of reducing sugars was determined by Dinitrosalicylate method. Attempts were made to optimize the various cultural parameters such as pH, temperature, carbon and nitrogen sources for enhanced amylase productivity of S. cheonanensis VUK-A.

Results: Among the 20 actinobacterial strains screened, one isolate found to be potential and was identified by morphological, cultural, physiological, biochemical characteristics and 16S rRNA analysis. The strain was identified as Streptomyces cheonanensis VUK-A. The optimum pH and temperature for amylase production by the strain was found to be 7.0 and 30°C respectively. Different carbon and nitrogen sources were amended separately to the production medium to determine their effect on amylase production. The production of amylase by the strain was enhanced when cultured on ISP-4 broth amended with sorghum flour (30 mg/ml) and peptone (10 mg/ml) with pH 7.0 and incubated at 30°C for 72 h.

Conclusion: The present study revealed that Streptomyces cheonanensis VUK-A isolated from mangrove sediments yielded high amounts of amylase in the medium (ISP-4) amended with sorghum flour (30 mg/ml) and peptone (10 mg/ml) with initial pH 7.0 at 30°C after 72 h of incubation. The enzyme yield before optimization was 4.3 U/ml while it was 11.2 U/ml after optimization.