Characterization of alkaline proteases from a novel alkalitolerant bacterium Bacillus patagoniensis.

NELDA LILA OLIVERA; CYNTHIA SEQUEIROS,; FAUTINO SIÑERIZ,; JAVIER BRECCIA,

World Journal of Microbiology & Biotechnology

Springer Netherlands

Lugar: India; Año: 2006 vol. 22 p. 737 - 743

0959-3993

The extracellular proteolytic activity produced by a moderately alkaliphilic bacterium, Bacillus patagoniensis PAT 05T, was characterized. This strain, grown in a highly alkaline and saline medium, produced important levels of alkaline protease. SDS-PAGE and zymogram analyses revealed two proteolytic active bands. Through isoelectricfocusing (IEF)-zymogram, an active band with alkaline pI and two slighter active bands with acid pIs were detected. The alkaline active enzyme in the IEF was purified 57 times and characterized, its molecular mass was 29.4 kDa and its pI value >10.3. Proteolytic activity showed an optimal temperature of 60°C and a plato of maximum activity between pH 9.0 and 12.0. It was not affected by H2O2 (10 % v/v), 1,10-Phenanthroline (10 mmol l-1), Triton X-100 (1 % v/v) and Tween 20 (1 % v/v), under the assay conditions. More than 80 % of the activity was retained in 10 mmol l-1 EDTA, 73 % in 1 % (w/v) SDS and 63% in 2 mol l-1 NaCl. It was inhibited with PMSF, indicating serine-protease activity. The protease activity showed to be thermosensitive with a half-life of 2.3 min at 70°C, while high activity was detected at moderate temperatures. Considering the PAT 05T protease characteristics, such as high optimum pH, high stability and residual activity in presence of oxidant, surfactant and chelating agents, this strain could be a potential source of enzymes to be used as additive in detergent formulation or in the leather industry.