ISSN: 0973-7510
E-ISSN: 2581-690X
In order to improve acid tolerance of Bacillus amyloliquefaciens a-amylase, error-prone PCR was used to randomize mutagenesis of the a-amylase gene from Bacillus amyloliquefaciens, and a mutant G300H was selected. The a-amylase activity of the mutant G300H (1,887 U/mg) was 9.6% higher than that of the wild type (WT) (1,722 U/mg). At pH 4.0, the a-amylase activity of the mutant G300H and the WT were 804 and 522 U/mg, respectively; this finding suggested that the acid tolerance of a-amylase G300H was 54.0% higher than that of the WT. The residual a-amylase activities of the mutant G300H and WT were 684 and 206 U/mg, respectively, after treatment at 70°C for 5 min, suggesting that the thermostability of a-amylase G300H was 2.3× higher than that of the WT. The Km of the a-amylase and the WT were 5.033 and 5.63 mg/mL, respectively, which indicated that the catalyzing efficiency of G300H was improved.
Acid tolerance, a-amylase, Bacillus amyloliquefaciens, Error-prone PCR
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