Purification, properties and mass spectrometry analysis of two novel thermotolerant endoglucanases from Bacillus akihai I -2

摘要

The alkaliphilic bacterium strain I -2, which was isolated from soda lakes, was identified as Bacillus akibai by 16S rRNA sequence analysis and suggested to be a new subspecies of genus Bacillus. Two novel thermotolerant alkaline endoglucanases I -2-A and I -2-B were produced by this alkaliphilic strain. The purified I -2-A and I -2-B had molecular mass of approximately 60 and 90 kDa, respectively. The optimum pH of I -2-A was about 9.0, while that of I -2-B was about 8.0. Both enzymes exhibited maximum activity at around 50 °C and were stable up to 50 °C .The two enzymes were resistant to most metal ions and reagents examined. Mass spectrometry analysis indicated that I -2-A was probably different from the endoglucanases reported. I -2-B showed homology with those of family A5 endoglucanases but low similarity was found in C-terminal amino acid sequence.