Purification and Characterization of a Liquefying α-Amylase from Alkalophilic Thermophilic Bacillus sp. AAH-31

• Published in: Bioscience, biotechnology, and biochemistry Vol. 76; no. 7; pp. 1378 - 1383
• Main Authors: KIM, Dae Hoon, MORIMOTO, Naoki, SABURI, Wataru, MUKAI, Atsushi, IMOTO, Koji, TAKEHANA, Toshihiko, KOIKE, Seiji, MORI, Haruhide, MATSUI, Hirokazu
• Format: Journal Article
• Language: English
• Published: Tokyo Japan Society for Bioscience, Biotechnology, and Agrochemistry 2012; Japan Society for Bioscience Biotechnology and Agrochemistry
• Subjects: alpha-Amylases - isolation & purification; alpha-Amylases - metabolism; Amylose - metabolism; Bacillus - chemistry; Bacillus - enzymology; Bacillus sp; Bacterial Proteins - isolation & purification; Bacterial Proteins - metabolism; Biological and medical sciences; Calcium - metabolism; Edetic Acid - chemistry; Electrophoresis, Polyacrylamide Gel; Enzyme Stability; Fundamental and applied biological sciences. Psychology; gamma-Cyclodextrins - metabolism; Hot Temperature; Hydrogen-Ion Concentration; Kinetics; Molecular Weight; Octoxynol - chemistry; Polysorbates - chemistry; purification; Sodium Dodecyl Sulfate - chemistry; Soil Microbiology; Starch - metabolism; Substrate Specificity; thermostability; α-amylase; Purification; Enzyme; Alkalophily; thermostability; Thermophily; Bacillaceae; Thermal stability; Glycosylases; Characterization; Bacillales; Bacillus sp; Glycosidases; Substrate specificity; Bacillus; Bacteria; Hydrolases; α-Amylase
• ISSN: 0916-8451; 1347-6947
• DOI: 10.1271/bbb.120164

α-Amylase (EC 3.2.1.1) hydrolyzes an internal α-1,4-glucosidic linkage of starch and related glucans. Alkalophilic liquefying enzymes from Bacillus species are utilized as additives in dishwashing and laundry detergents. In this study, we found that Bacillus sp. AAH-31, isolated from soil, produced an alkalophilic liquefying α-amylase with high thermostability. Extracellular α-amylase from Bacillus sp. AAH-31 (AmyL) was purified in seven steps. The purified enzyme showed a single band of 91 kDa on SDS-PAGE. Its specific activity of hydrolysis of 0.5% soluble starch was 16.7 U/mg. Its optimum pH and temperature were 8.5 and 70 °C respectively. It was stable in a pH range of 6.4-10.3 and below 60 °C. The calcium ion did not affect its thermostability, unlike typical α-amylases. It showed 84.9% of residual activity after incubation in the presence of 0.1% w/v of EDTA at 60 °C for 1 h. Other chelating reagents (nitrilotriacetic acid and tripolyphosphate) did not affect the activity at all. AmyL was fully stable in 1% w/v of Tween 20, Tween 80, and Triton X-100, and 0.1% w/v of SDS and commercial detergents. It showed higher activity towards amylose than towards amylopectin or glycogen. Its hydrolytic activity towards γ-cyclodextin was as high as towards short-chain amylose. Maltotriose was its minimum substrate, and maltose and maltotriose accumulated in the hydrolysis of maltooligosaccharides longer than maltotriose and soluble starch.