Melhoramento de Bacillus amyloliquefaciens por transformação e fusão, para produção de a-amilase e proteinas

AUTOR(ES)

Valter Roberto Linardi

DATA DE PUBLICAÇÃO

1985

RESUMO

Two different strains of Bacillus3 were used B. amyloliquefaciens ATCC 2342 and B. natto, isolated from the commercial product "Natto", good producer of α -amylase and of proteases, respectively. The level of production of these enzymes was increased through technique using transformant DNA and fusion of protoplasts. The genetic improvement by transformation was shown to be more eficient than that obtained by protoplast fusion. Among the various recombinant DNA s isolated and obtained by transformation, the T-41 and T-39 strains were selected. The former produced twice as much a-amylase and three times the quantity of proteases as the B. amyloliquefaciens, while the T-39 strain produced four times as much proteases as B. amyloliquefaciens. Comparative studies demonstrated that the a-amylase produced by the recipient had maximum activity at pH 6,0 and 65°C. At 60°C, the enzyme was stable for 60 minutes. Similarly, the enzyme produced by T-41 showed maximum activity at pH 6,0 and 65°C. At 60°C, the amylase activity began to decrease after 40 minutes, with a sharp decline in activity at 65°C. An analysis of the chromatogram indicated that the enzymes produced by these strains demonstrated the same type of activity on starch. The recombinant T-41 was shown to be more susceptible to cellular autolysis than B. amyloliquefaciens. The amylase activity of the F-52 strain, obtained by protoplast fusion, was twice that of the parent B. natto and only this recombinant developed the capacity to grow at 50°C.

ASSUNTO(S)

alimentos - analise

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