Isolasi Bakteri Penghasil Enzim Protease Alkalin Termostabil

Alina Akhdiya
Journal article Buletin Plasma Nutfah • Desember 2003 Indonesia


In the effort of obtaining indigenous alkaline thermosteble protease producing bacteria, 17 different soil samples collected from slaughterhouses, fish ponds along the Nusa Tenggara, and spoiled milk disposal sites in Boyolali (Central Java) for microbial isolation. Out of the 1004 colonies obtained, 29 isolates showed proteolytic index ≥3.00. Enzymatic assay on these isolates resulted in two isolates (BYL-15 and BYL-28) with highest crude enzyme activity, this activity was also higher than that achieved by the standard bacteria (Bacillus firmus NRRL B-1107). After 36 hours of incubation, crude enzyme activity and specific activity of isolate BYL-15 were 106.45 U/ml filtrate and 5069.04 U/mg protein, respectively (at 50°C and pH 10.5). Whereas for isolate BYL-28 the crude enzyme activity and specific activity were 100.00 U/ml filtrate and 5,263.15 U/mg protein, respectively. The activity of these two isolates were about 10 times higher than that of the B. firmus (11.259 U/ml filtrate), whereas their specific activities were about 40 times than that of B. firmus (119.78 U/mg protein). Further studies showed that the proteolytic activity of these two isolates were still increased when assayed at 60°C, and more than one peak of activity were obtained when assayed at different pH values (8.5-12). Based on microscopic observations, these two isolates showed cell morphology characteristics of Actinomycetes.


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