Enhanced extracellular production of α-amylase in Bacillus subtilis by optimization of regulatory elements and over-expression of PrsA lipoprotein
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α-Amylase was used as a heterologous model protein to investigate the effects of promoters, signal peptides and over-expression of an extra-cytoplasmic molecular chaperone, PrsA lipoprotein, on enhancing the secretion of α-amylase in Bacillus subtilis. Four promoters and six signal peptides were compared, successively, and the highest yield of α-amylase was achieved under the promotion mediated by PAprE, a strong constitutive promoter, and secretion by SPnprE, a signal peptide from B. subtilis. Moreover, under conditions of overexpressed PrsA lipoprotein, the secretion production and activity of α-amylase increased to 2.5-fold. The performance of the recombinant B. subtilis 1A751PL31 was evaluated with a fed-batch fermentation in a 7.5 l fermentor. Optimization of regulatory elements and over-expression of PrsA lipoprotein had a significant effect on enhancing the production of α-amylase in B. subtilis.
Keywordsα-Amylase Bacillus subtilis Fed-batch fermentation Promoter PrsA Regulatory elements Signal peptide
This research was supported by grants from National Nature Science Foundation of China (31200036, 31370089), the State Key Development Program for Basic Research of China (973 Program, 2013CB733600), and the Key Projects in the Tianjin Science & Technology Pillar Program (14ZCZDSY00065).
Supplementary Table 1—Strains and plasmids used in this study.
Supplementary Table 2—Primers used in this study.
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