RESUMO
A salt-tolerant cellulase secreted by a marine Bacillus sp. SR22 strain with wide resistance to temperature and pH was purified and characterized. Its approximate mass was 37 kDa. The endoglucanase, named as Bc22Cel, was purified by ammonium sulfate precipitation, gel filtration chromatography, and extraction from the gel after non-reducing sodium dodecyl sufate-polyacrylamide gel electrophoresis. The optimal pH value and temperature of Bc22Cel were 6.5 and 60°C, respectively. The purified Bc22Cel showed a considerable halophilic property, being able to maintain more than 70% of residual activity even when pre-incubated with 1.5 M NaCl for 1 h. Kinetic analysis of the purified enzyme showed the Km and Vmax to be 0.704 mg/ml and 29.85 µmol·ml-1·min-1, respectively. Taken together, the present data indicate Bc22Cel as a potential and useful candidate for industrial applications, such as the bioconversion of sugarcane bagasse to its derivatives.
Assuntos
Bacillus/enzimologia , Proteínas de Bactérias/metabolismo , Celulase/química , Celulase/isolamento & purificação , Água do Mar/microbiologia , Bacillus/genética , Bacillus/isolamento & purificação , Bacillus/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/isolamento & purificação , Brasil , Celulase/classificação , Celulase/efeitos dos fármacos , Celulose/metabolismo , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Microbiologia Industrial , Cinética , Peso Molecular , Filogenia , RNA Ribossômico 16S/genética , Saccharum/metabolismo , Cloreto de Sódio/farmacologia , Especificidade por Substrato , TemperaturaRESUMO
Studies on the alpha-amylase production were carried out with a bacterial strain isolated from a soil sample. The cells were cultivated in a mineral medium containing soluble starch as sole carbon source. The addition of calcium (10 mM) or peptone (1%) and yeast extract (0.5%) to the mineral medium shortened the lag period and improved the growth and alpha-amylase synthesis. The addition of glucose to the culture diminished greatly the synthesis of alpha-amylase, demonstrating that a classical glucose effect is operative in this organism. The optimum temperature and initial medium pH for amylase synthesis by the organism were 50°C and 7.0 respectively. The optimal pH and temperature for activity were 6.0 and 50°C respectively. The enzyme extract retained 100% activity when incubated for one hour at 90°C and 40% at 60°C for 24 h. The addition of glucose to the culture diminished greatly the synthesis of alpha-amylase.
Estudos sobre a produção de alfa-amilase foram realizados com uma bactéria isolada a partir de amostras de solo. As células foram cultivadas em um meio mineral contendo amido como única fonte de carbono. A adição de cálcio (10mM) ou peptona (1,0%) e extrato de levedura (0,5%) ao meio mineral, encurtou o período lag, melhorou o crescimento e a síntese de alfa-amilase. A adição de glicose a cultura diminuiu grandemente a síntese de alfa-amilase, demonstrando que o efeito glicose ocorre neste microrganismo. A temperatura ótima e o pH inicial ótimo para a síntese da amilase pelo organismo foram 50ºC e 7,0 respectivamente. O pH e temperatura ótima para atividade foram 6,0 e 50ºC respectivamente. O extrato enzimático reteve 100% de atividade quando incubado por uma hora a 90ºC e 40% a 60ºC por 24 horas. A adição de glicose ao meio de cultura diminuiu grandemente a síntese de alfa-amilase.