Whole-cell oxidation of omeprazole sulfide to enantiopure esomeprazole with Lysinibacillus sp. B71

► Whole-cell oxidation of omeprazole sulfide to esomeprazole by Lysinibacillus sp. ► Screening among 1000 strains yielded five strains with (S) ee. ► Optimization of transformation in fed-batch bioreactor culture. ► Yield of esomeprazole up to 77%, ee 100% and no sulfone production.