Enhanced validamycin production and gene expression at elevated temperature in Streptomyces hygroscopicus subsp jingangensis 5008

Cultivation shift from 30A degrees to 37A degrees significantly enhanced validamycin (VAL) production. Analyzed by reverse-transcription PCR, the transcription of three val genes, valA, valK and valG, representing the three operons of the cluster was simultaneously increased at elevated temperature. Furthermore, the transcription of valP and valQ, a pair of two-component regulators in validamycin biosynthetic gene cluster, was also increased at 37A degrees. Inactivation of valP and valQ reduced validamycin production at 37A degrees to the yield level of wild type strain at 30A degrees, and the val genes showed reduced expression in the mutant LL-8 at 37A degrees. These results revealed that the two-component regulator valP and valQ contribute to the elevated validamycin production.