Construction and optimization of genetically engineered bacteria producing L-arabinose isomerase
L-arabinose isomerase(L-AI)can specifically act on the substrate D-galactose to produce D-tagatose.To obtain a high-yield L-AI strain,the L-AI coding gene araA gene derived from L.brevis sp.D-tag1 was connected to pET-30a(+)expression plasmid to construct a recombinant plasmid.Then the recombinant plasmid was transferred into E.coli BL21(DE3)by heat shock method,and E.coli BL21(DE3)/pET-30a(+)-araA was constructed.The codon optimization of araA gene was carried out according to the codon preference of host E.coil.The optimized araAo gene was connected to pET-30a(+),then transferred into E.coli BL21(DE3)to construct E.coli BL21(DE3)/pET-30a(+)-araAo.The results showed the optimized strain showed a significant increase in expression levels compared to the unoptimized strain,with an increase in enzyme activity of 79.2％.
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