Resumo
An alkaliphilic and highly thermostable -amylase producing Bacillus sp. was isolated from Van soda lake. Enzyme synthesis occurred at temperatures between 25ºC and 40ºC. Analysis of the enzyme by SDS-PAGE revealed a single band which was estimated to be 66 kDa. The enzyme was active in a broad temperature range, between 20ºC and 90ºC, with an optimum at 50ºC; and maximum activity was at pH 10.5. The enzyme was almost completely stable up to 80ºC with a remaining activity over 90% after 30 min pre-incubation. Thermostability was not increased in the presence of Ca2+. An average of 75% and 60ºC of remaining activity was observed when the enzyme was incubated between pH 5 and 9 for 1 h and for 2 h, respectively. The activity of the enzyme was inhibited by SDS and EDTA by 38% and 34%, respectively.
Bacillus sp AB68 alcalifílico produtor de -amilase alcalina termoestável foi isolado do lago Van soda. A síntese da enzima ocorreu entre 25ºC e 40ºC. A análise da enzima por SDS-PAGE revelou uma única banda estimada em 66 kDa. A enzima foi ativa em uma ampla faixa de temperatura, entre 20ºC e 90ºC, com um ótimo a 50ºC. A atividade máxima foi em pH 10,5. A enzima foi estável até 80ºC, mantendo 90% de atividade após 30 min de pré-incubação. A termoestabilidade não aumentou na presença de Ca2+. Quando incubada em pH entre 5 e 9 por 1h e por 2h, a enzima manteve 75% e 60% de atividade, respectivamente. SDS e EDTA causaram redução de 38% e 34% na atividade da enzima, respectivamente.