Isolation and characterization of alkaline amylase producers from the marine environment of Arabian sea coast

Alkaline amylase producers were isolated from the marine environment of Arabian Sea coast. A total of 10 isolates were obtained from the soil and water samples collected from the marine environment. Five isolates namely; BCSS, JBWS, RBWS, BCWS and ALSS showed good growth on alkaline M9 media with 10% NaCl having starch as the primary carbon source. Based on their maximal amylase activity, three microbial cultures (BCSS, JBWS, and RBWS) were selected for the study. The crude enzyme from these purified cultures was extracted and partial characterization was carried out. The partial characterization study involved the effect of metal ions and surfactants and determination of optimal pH and temperature and its stability studies. The amylase activity was optimum for all three cultures at 60 0C whereas, the optimum pH was found to be pH 7, pH 8 and pH 9 for RBWS, JBWS and BCSS. The pH and temperature stability studies showed maximum amylase activity at its optimal conditions for 5h (300 mins) in the order BCSS>RBWS>JBWS. The amylase activity was found to increase with sodium (BCSS), manganese (RBWS) and potassium (JBWS) at 1:1 dilution. The cultures were stable with the surfactants (Tween -20, SDS and Triton-X) at 1:10 dilution of 1% surfactant and enzyme. BCSS was the most stable at high temperature and pH among all the isolates with an optimal amylase activity at pH 9 and temperature of 60 0C. The isolate was identified to be Bacillus nanhaiisediminis NH3. These remarkable properties indicated its great potential in industrial applications.