Codon Optimization Significantly Improves the Expression Level ofα-Amylase Gene fromBacillus licheniformisinPichia pastoris

摘要

α-Amylase as an important industrial enzyme has been widely used in starch processing, detergent, and paper industries. To improve expression efficiency of recombinantα-amylase fromBacillus licheniformis(B. licheniformis), theα-amylase gene fromB. licheniformiswas optimized according to the codon usage ofPichia pastoris(P. pastoris) and expressed inP. pastoris. Totally, the codons encoding 305 amino acids were optimized in which a total of 328 nucleotides were changed and the G+C content was increased from 47.6 to 49.2%. The recombinants were cultured in 96-deep-well microplates and screened by a new plate assay method. Compared with the wild-type gene, the optimized gene is expressed at a significantly higher level inP. pastorisafter methanol induction for 168 h in 5- and 50-L bioreactor with the maximum activity of 8100 and 11000 U/mL, which was 2.31- and 2.62-fold higher than that by wild-type gene. The improved expression level makes the enzyme a good candidate forα-amylase production in industrial use.