Journal of Microbiology and Biotechnology   2016 年 26 卷 6 期

2016.06.28

The gene encoding lipase (Lip98) from Aeromicrobium sp. SCSIO 25071 was cloned and functionally expressed in Escherichia coli. Lip98 amino acid sequence shares the highest (49%) identity to Rhodococcus jostii RHA1 lipase and contains a novel motif (GHSEG), which is different from other clusters in the lipase superfamily. The recombinant lipase was purified to homogeneity with Ni-NTA affinity chromatography. Lip98 showed an apparent molecular mass of 30 kDa on SDS gel. The optimal temperature and pH value for enzymatic activity were recorded at 30?°C and 7.5, respectively. Lip98 exhibited high activity at low temperatures with 35% maximum activity at 0?°C and good stability at temperatures below 35?°C. Its calculated activation energy was 4.12 kcal/mol at the low temperature range of 15-30?°C. Its activity was slightly affected by some metal ions such as K