Increased vulnerability to physical stress by inactivation of NdgR in Streptomyces coelicolor

The role of NdgR in glycerol metabolism in Streptomyces coelicolor

Streptomyces, which produces many pharmaceutical antibiotics and anticancer agents, is a genus of soil-dwelling bacteria with numerous regulators that control both primary and secondary metabolism. NdgR is highly conserved in Streptomyces spp. and is known to be involved in antibiotic production, tolerance against shock and physical stress, nitrogen metabolism, leucine metabolism, and N-acetylglucosamine metabolism. As another function of NdgR, we report the involvement of NdgR in glycerol metabolism in S. coelicolor. Initially, a glycerol utilization operon containing gylCABX was found to be up-regulated in an ndgR deletion mutant (BG11) grown in N-acetylglucosamine solid minimal media compared with wild-type strain (M145). BG11 produced more antibiotics with a small amount of glycerol and increased glycerol utilization, yielding higher concentrations of lactate and acetate per cell. Moreover, fatty acid production was also changed in BG11 to produce longer chain fatty acids, phenolic compounds, alkanes, and fatty alcohols. Using a gel retardation assay, NdgR was found to bind the upstream region of gylC, working as a repressor. NdgR is a second regulator of a glycerol utilization operon, for which only one regulator, GylR was previously known.