Isolation And Identification Of Protease Producing Bacteria From Various Sources Related To Hevea brasiliensis
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Date
2011-05
Authors
Pauzi, Norlin
Journal Title
Journal ISSN
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Publisher
Universiti Sains Malaysia
Abstract
Screening and isolation of proteolytic bacteria were carried out from Hevea brasiliensis tree including from bark, fresh latex, coagulated rubber, soil around the tree, latex from processing tank, residual latex on soil and effluent from effluent treatment pond. Fifteen isolates showed hydrolysis on 10 % of skim milk agar, indicating protease production from these isolates. Among the isolates, three were identified as Bacillus sp. and were selected for further study, designated as Strain K, Strain M and Strain O. Strain K and Strain O showed growth temperatures as high as 45 ºC within a broad pH range of 4 to 10. Preliminary results showed that both bacterial isolates grew best at 37 ºC and pH 7. Strain M showed optimal growth at 37 ºC and pH 9. All isolates produced the highest protease activity at 200 rpm. Strain K produced the highest protease activity around 84 U/ml in a TSB medium with 1 % glucose added. Strain M produced the highest protease activity around 158 U/ml in a medium containing 0.5 % glucose, 0.75 % peptone, 0.5 % KH2PO4, 0.5 % MgSO4 and 0.01 % FeSO4. Both of these strains showed an incremental in enzyme production when induced with peptone. These isolates also showed growth and protease activity in natural rubber serum. However to obtain significant growth and protease production, natural rubber serum needs to be supplemented with basal medium and glucose. When the supernatant of Strain M containing proteases were applied to latex, there was a reduction of almost 80 % of the nitrogen content in the dry rubber within 72 hours. Centrifugation process of the latex was found to be a good method in improving the latex condition for better degradation of protein. The enzymes also showed good stability in the presence of N10 and HNS, which work as stabilizer.
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Keywords
Screening and isolation of proteolytic bacteria , from Hevea brasiliensis tree