RESUMO
An alkaliphile bacterial strain designated as CH11 was isolated from the sediments of Chilika Lake, Odisha. The isolate showed stupendous growth and production of α-amylase at pH 10.0. Through 16S rRNA gene based molecular technique this isolate was identified as Bacillus cereus strain SP-CH11 having GenBank Accession No. KT992791. Homogenous ~55 kDa extracellular α-amylase was extracted with 241.304, 26.26 and 3.2-fold acceleration in specific activity, purification fold and yield respectively. The alkaline α-amylase AA11 was further characterized. At pH 9.0 the purified enzyme AA11 was highly stable while retaining 88-100% functional viability at temperature range from 35 to 65 °C, confirming its thermostability nature. It showed stability with powdered and liquid detergents at 7 mg/mL and 100-fold dilutions respectively. AA11 efficiently removed the starch stain from cotton fabrics. The findings of this study indicate that the isolate CH11 is a source of novel alkaline α-amylase that has promising application in food and detergent industries.
Assuntos
Bacillus cereus/enzimologia , alfa-Amilases/biossíntese , alfa-Amilases/química , Bacillus cereus/genética , Bacillus cereus/isolamento & purificação , Sequência de Bases , Fenômenos Químicos , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Cinética , Lagos , Peso Molecular , Conformação de Ácido Nucleico , Filogenia , Temperatura , Microbiologia da Água , alfa-Amilases/genética , alfa-Amilases/isolamento & purificaçãoRESUMO
An alkali-tolerant bacterial isolate CH7 was isolated from Chilika Lake sediments that produced α-amylase at high pH. It showed >15â¯mm zone diameter at pHâ¯11.0 on agar plate containing 1% starch hence considered for study. It survived up to 10% NaCl concentration on nutrient agar plates. Taxonomically it was identified as Bacillus sp. strain SP-CH7 having GenBank Accession No. KU761266. Optimized alkaline α-amylase, AA7 showed 202.857 specific activity (IU/mg), 65.95 purification fold and 25.94 yield (%) respectively. Molecular weight was revealed by SDS-PAGE as 55â¯kDa. The Km value was 0.688â¯mg/mL and so was 2.342â¯IU/mL Vmax obtained for AA7 towards starch. This enzyme showed 92.79% and 91.14% stability at pHâ¯11.0 and 13.0 respectively and up to 75⯰C stability was also noted. Enzyme activity was stimulated by Co2+, Na+ and Ca2+. It was stable in presence of EDTA, SDS, all the powdered detergents as well as with liquid detergent "Ezee" which vouches for its potential application in Detergent industries.
