Assisting biorecycling of bioorganic wastes by enzymatic approaches

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We isolated an acidophilic thermophile belonging to the genus Bacillus, strain NTAP-1, which secreted a thermostable collagenolytic activity into the culture medium. The collagenolytic activity exhibited an optimum ph for Azocoll hydrolysis of ph 3.9 and was not completely inhibited by 10 Mm ethylenediaminetetraacetic acid (residual activity, 63 % ), suggesting that Bacillus NTAP-1 produces a novel acid proteinase with highest activity for collagen. The collagenolytic activity was thermostable; more than 80 % of the original activity was retained after incubation of the culture supernatant at ph 4.0 and 60 ℃ for 4h. We also isolated a Kpolytic bacterium, strain No. 6, from Siberian tundra soil. It was a Gram-negative coccoid rod capable of growing at 4 ℃ but not at 37 ℃ and was identified as a psychrotrophic strain of the genus Acinetobacter. Strain No.6 extracellularly produced a lipolytic enzyme that efficiently hydrolyzed triglycerides such as soybean oil during bacterial growth even at 4 ℃ ; it degraded 60 % of added soybean oil (initial concentration, 1 % w/v) after cultivation in LB medium at 4 ℃ for 7d. Thus, the bacterium is potentially applicable to in-situ bioremediation or bioaugumentation of fat-contaminated cold environments. We partially purified the lipolytic enzyme from the culture filtrate by acetone fractionation and characterized it.