Forty-four Bacillus spp. strains obtained from sugar cane derivates and residues, six of them isolated in this work, were tested using Tween 80 as substrate (agar-Tween 80 medium), in order to determine their esterase activity through the enzymatic index averages. After statistic analysis, B. cereus (C124) strain, which presented better results, was submitted to genetic improvement by treatment with ultraviolet light (UV). The survival curve pointed out 28" as the time necessary to obtain 30% of survivors. Fifty survivors and the wild strain C124 were compared in relation to their esterase activity as mentioned previously. The wild strain and the mutant C124UV35, which showed enzymatic index average higher than C124, were characterized in polyacrilamide gel electrophoresis (PAGE). Eletrophoretic patterns for total proteins of wild and mutant strain showed different profiles according to number, position and intensity of bands. For esterase, the bands varied only in intensity.
Bacteria; genetic improvement; Bacillus spp.; B. cereus; esterase
