The stringent response gene rsh plays multiple roles in Novosphingobium pentaromativorans US6-1?s accommodation to different environmental pollutants: Phenanthrene, copper and nZVI

The rsh based stringent response system is widely employed by bacteria to cope with environmental stresses. However, how does the stringent response involve in bacterial accommodation to environmental pollutant is largely unexplored. In this study, to comprehensively understand the roles of rsh in Novosphingobium pentar-omativorans US6-1's metabolism and accommodation to different pollutants, three distinct pollutants, phenan-threne, copper and nanoparticulated zero valent iron (nZVI) were selected as exposure substances. Results indicated that rsh played important roles in US6-1's multiplication and metabolism, including survival rate at stationary phase, amino acid and nucleotide metabolism, extracellular polymeric substance (EPS) production, redox homeostasis, etc. The deletion of rsh affected phenanthrene removal rates through regulating the multi-plication of US6-1 and increasing the expression of degradation related genes. The rsh mutant showed higher resistance to copper than the wild type, largely due to higher EPS production and enhanced expression of copper resistance related genes. Finally, the rsh based stringent response helped maintain the redox homeostasis when US6-1 confronted nZVI particles that exerted oxidative stress, thereby improving the survival rate. Overall, this study provides firsthand data that rsh plays multiple roles in US6-1's accommodation to environmental pollut-ants. The stringent response system could be a powerful tool for environmental scientists and engineers to harness bacterial activities for bioremediation purposes.

Automated summary

This study reveals the important roles of rsh in Novosphingobium pentar-omativorans US6-1's metabolism and accommodation to different pollutants. The results show that rsh affects US6-1's multiplication and metabolism, including survival rate, amino acid and nucleotide metabolism, EPS production, and redox homeostasis. The stringent response system based on rsh can help maintain redox homeostasis and improve survival rate when facing oxidative stress. The findings provide valuable data for environmental scientists and engineers to harness bacterial activities for bioremediation purposes.