Enhancement of A82846B yield and proportion by overexpressing the halogenase gene in Amycolatopsis orientalis SIPI18099

The glycopeptide antibiotic A82846B (chloroeremomycin) produced by Amycolatopsis orientalis is the precursor of the semi-synthetic antibiotic oritavancin. However, during the industrial production of A82846B, two major impurities, A82846A (63.6%) and A82846C (12%) which are structurally similar to A82846B (24.4%), are also produced. In this study, to improve the ratio of A82846B to A and C, the genes encoding halogenase in A82846B and vancomycin synthesis were integrated into A. orientalis SIPI18099 to test their halogenation ability, respectively. The results indicated that chal from the A82846B biosynthesis pathway was more efficient in reducing A and C factors. Moreover, by increasing the chal copy number, the proportion of A and C were gradually reduced while the titer and proportion of A82846B were improved. In a scaled-up industrial process, the proportion of A and C were decreased to 11.6% and 0.2% in the recombinant strain A.orientalis chal-3 with three gene copies of chal and the titers of A82846B (2.2 g/L) has increased by 2.8-folds compared to 780 mg/L produced by the parental strain, suggesting that the recombinant strain was suitable for the industrial production of A82846B with lower impurities.