Bacillus spp. produtores de protease: isolamento, caracterizaçäo e melhoramento de B. cereus (C124) / Bacillus spp. protease producers: isolation, characterization and genetic improvement of B. cereus (C124)

RESUMO

Forty-four Bacillus spp, strains obtained from sugar cane derivates and residues, six of them isolated in this work, were tested in two different substracts, hemoglobin (agar-hemoglobin and agar-hematia 9erythrocyte) media) and casein (agar-milk medium), in order to determine their proteolytic activity through the enzymatic index averages. After statistic analysis, B. cereus (C124) strain, which presented better results in all media, was submitted to genetic improvement by treatment with ultraviolet light(UV). The survival curve pointed out 28" as the time necessary to obtain 30 per cent of survivors. Fifty survivors and the wild strain C124 were compared in relation to their proteolytic activity as mentioned previously. The wild strain, and the mutants C124UV18, C124UV35, C124UV37 and C124uv47, which presented enzymatic index averages higher than C124, were characterized in polyacrilamide gel eletrophoresis (PAGE). Eletrophoretic patterns for total proteins of wild and mutant strains showed different profiles according to number, position and intensity of bands. For esterase, the bands varied only in intensity