Characterization and preliminary mutation analysis of a thermostable alanine racemase from Thermoanaerobacter tengcongensis MB4.

A thermostable alanine racemase from Thermoanaerobacter tengcongensis MB4 was successfully expressed in Escherichia coli and characterized. The full-length gene MBalr2 (1164 bp) encodes 388 amino acid residues including 6 out of 8 highly conserved amino acid residues at the entryway to the active site of alanine racemase. Recombinant MBAlr2 and three mutants (S171A, H359Y and double mutation S171A/H359Y) of MBAlr2 were purified by His6-tag affinity column and gel filtration chromatography.

Jerusalem artichoke powder: a useful material in producing high-optical-purity l-lactate using an efficient sugar-utilizing thermophilic Bacillus coagulans strain.

Jerusalem artichoke is a low-requirement crop, which does not interfere with food chain, and is a promising carbon source for industrial fermentation. Microbial conversion of such a renewable raw material to useful products, such as lactic acid, is an important objective in industrial biotechnology. In this study, high-optical-purity l-lactate was efficiently produced from the hydrolysates of Jerusalem artichoke powder by a thermophilic bacterium, Bacillus coagulans XZL4.

Efficient production of polymer-grade L-lactic acid from corn stover hydrolyzate by thermophilic Bacillus sp. strain XZL4.

Lactic acid has been identified as one of the top 30 potential building-block chemicals from biomass. Therefore, the search for cheap raw materials is an objective to reduce the production costs. Efficient polymer-grade L-lactic acid production was achieved in this report by a thermophilic strain Bacillus sp.

[Identification of the catalytic residues of mannanase from Alicyclobacillus acidocaldarius].

Objective: To identify the catalytic residues of mannanase AaManA from Alicyclobacillus acidocaldarius.

Methods: Based on the sequence alignment by ClustalX and ESPript and the structure information of GH -53 family, the possible catalytic residues were selected and mutated by overlap extension PCR. The protein of wild type and mutant were expressed in E.