碩士 / 國立臺灣大學 / 海洋研究所 / 99 / In this study, 167 isolates of psychrotolerant bacteria had been tested for their protease activity. 65 isolates were observed to possess positive protease activity, 7 isolates of these, with higher protease activity were identified as members of the genus Vibrio and Pseudoalteromonas. The bacterial isolate, strain D1, exhibiting the best protease activity was selected for protease purification and the purified protease was further used for characterization. Molecular weight of protease determined by gel filtration (Sephacryl S-200) was approximately 168 kDa. Protease was active over a wide temperature range of 4-70 ℃ and significant activity was observed between 20 to 60 ℃with maximum activity at 50 ℃. The optimal pH range for protease activity was pH 7-8. Enzyme activity was completely inhibited by phenylmethyl sulphonyl fluoride (PMSF) and ethylene diamine tetra acetic acid (EDTA). Apparantly, no remarkable effects were observed of metal ions on the protease activity, except Hg2+, which completely inactivated the protease. Protease was stable in presence of surfactants SDS (1-2 %), Tween 20 (0.5-2 %) and Triton (0.5-2 %). According to the results, protease obtained from strain D1 is suitable for food industry and detergent additives.
| Identifer | oai:union.ndltd.org:TW/099NTU05279013 |
| Date | January 2011 |
| Creators | Kuan Hsun Huang, 黃冠勳 |
| Contributors | 謝文陽 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 83 |
Page generated in 0.0011 seconds