中国生物工程杂志

Thermostable L-arabinose isomerase (L-AI) is the most potential enzyme for the biological production of D-tagatose from D-galactose, a novel functional factor. Gene araA encoding the L-arabinose isomerase from Bacillus stearothermophilis IAM 11001 was cloned and expressed in Escherichia coli. The araA gene of 1491 bp has 95% identity with L-AI from Thermus sp. IM6501. The GenBank accession number for the nucleotide sequence of this araA gene determined in this work is EU394214.The bacterium was induced by IPTG and analyzed by SDS - PAGE, approximately 59 kDa exogenous protein was observed on the SDS - PAGE. The recombinant L-AI was purified to electrophoretical homogeneity with affinity chromatography, and the activity of recombinant L-AI was also studied. The bioconversion rate of D-galactose to D-tagatose reached 39.4% after 24 h whole cell reaction.