RESUMO
A gene encoding a -1,3-1,4-glucanase (CelA) belonging to family 5 of glycoside hydrolases was cloned and sequenced from the Bacillus subtilis A8-8. The open-reading-frame of celA comprised 1499 base pairs and the enzyme was composed of 500 amino acids with a molecular mass of 55 kDa. The recombinant -1,3-1,4 glucanase was purified by GST-fusion purification system. The pH and temperature optima of the enzyme were 8.0 and 60oC, respectively. The enzyme was stable within pH 6.0-9.0. It was stable up to 60oC and retained 30% of its original activity at 70oC for 60 min. It hydrolyzed lichenan, CMC, xylan, laminarin, avicel and pNPC, but was inactive towards cellobiose. The enzyme activity was markedly activated by Co2+ and Mn2+, but was strongly inactivated by Fe3+. The truncated gene, devoid of cellulose-binding domain (CBD) showed 60% of activity and bound to avicel.
Assuntos
Bacillus subtilis/enzimologia , Bacillus subtilis/genética , Domínio Catalítico , Celulose/química , Clonagem Molecular , Cobalto/química , Endo-1,3(4)-beta-Glucanase/química , Glucanos/química , Concentração de Íons de Hidrogênio , Hidrólise , Manganês/química , Polissacarídeos/química , Proteínas Recombinantes/química , Temperatura , Xilanos/químicaRESUMO
A mineral phosphate solubilizing bacterium, Burkholderia cepacia DA23 has been isolated from cultivated soils. Phosphate-solubilizing activities of the strain against three types of insoluble phosphate were quantitatively determined. When 3 percent of glucose concentration was used for carbon source, the strain had a marked mineral phosphate-solubilizing activity. Mineral phosphate solubilization was directly related to the pH drop by the strain. Analysis of the culture medium by high pressure liquid chromatography identified gluconic acid as the main organic acid released by Burkholderia cepacia DA23. Gluconic acid production was apparently the result of the glucose dehydrogenase activity and glucose dehydrogenase was affected by phosphate regulation.
Uma bactéria capaz de solubilizar fosfato mineral, Burkholderia cepacea DA23, foi isolada de solo cultivado. A capacidade dessa bactéria solubilizar o fosfato de três tipos de fosfato insolúvel foi quantificada. Quando foi utilizada glicose a 3 por cento como fonte de carbono, a bactéria apresentou uma intensa atividade solubilizante de fosfato, sendo a solubilização diretamente relacionada com a queda de pH causada pela bactéria. A análise do meio de cultura por cromatografia líquida de alta pressão indicou o ácido glicônico como principal ácido produzido por Burkholderia cepacea DA23. Aparentemente, a produção de ácido glicônico foi causada pela atividade da glicose desidrogenase. A enzima foi afetada pela regulação do fosfato.