UPLC-qTOF-HR-MS analysis of the OMSs and derivatives produced by the wild-type and mutant strains of Streptomyces sp. SNJ042. Chromatograms are shown for selected m/z values of naturally occurring OMS A (1, [M+H]+ = 1458.89) and OMS B (2, [M+H]+ = 1472.91) and the derivatives produced by each mutant strain. (A) Chromatogram of OMS A (1) and OMS B (2) produced from the wild-type strain. (B) Chromatogram of dehydroxy-OMS A (4, [M+H]+ = 1442.90) and dehydroxy-OMS B (5, [M+H]+ = 1456.91) produced from the ΔohmL strain. (C) Chromatogram of demethoxy-OMS A (6, [M+H]+ = 1428.88) and demethoxy-OMS B (7, [M+H]+ = 1442.90) produced from the ΔohmK strain. (D) Chromatogram of OMS A (1) and OMS B (2) produced from the ΔohmK/ohmK strain. (E) Chromatogram of demethoxy-OMS A (6, [M+H]+ = 1428.88) and demethoxy-OMS B (7, [M+H]+ = 1442.90) produced from ΔohmJ strain. (F) Chromatogram of OMS A (1) and OMS B (2) produced from the ΔohmJ/ohmJ strain. (G) Chromatogram of demethoxy-OMS A (6, [M+H]+ = 1428.88) and demethoxy-OMS B (7, [M+H]+ = 1442.90) produced from ΔohmJ/ohmK strain.