Bacillus sp. AIR-5, a strain from soil, produced an extracellular maltohentaose-forming amylase from amylose and soluble starch. This bacterium produced 8.9g/l of maltopentaose from 40g/l of soluble starch in a batch fermentation and the maltopentaose...
Bacillus sp. AIR-5, a strain from soil, produced an extracellular maltohentaose-forming amylase from amylose and soluble starch. This bacterium produced 8.9g/l of maltopentaose from 40g/l of soluble starch in a batch fermentation and the maltopentaose made up 90% of the maltooligosaccharides produced (from maltose to maltoheptaose). The culture supernatant was concentrated using a 30K molecular weight cut-off membrane and purified by DEAE-Cellulose and Sephadex G-150 column chromatographies. The purified protein showed one band on a native-PAGE and its molecular mass was estimated as 250kDa. The 250-kDa protein was composed of tetramers of a 63-kDa protein. The isoelectric point of the purified protein was pH 6.9, and the optimum temperature for the enzyme activity was 45℃. The enzyme was quickly inactivated above 55℃, and showed a maximum activity at pH 8.5 and over 90% stability between a pH of 6 to 10. The putative N-terminal amino acid sequence of AIR-5 amylase, ATINNGTLMQYFEWYVPNDG, showed a 96% sequence similarity with that of BLA, a general liquefying amylase.