Highly efficient production of prodigiosin from corn stover hydrolysate in Serratia marcescens mutant RZ 21-6C generated by atmospheric and room‑temperature plasma mutagenesis.

Prodigiosin, a natural pigment mainly produced by microorganisms, has a wide range of applications in medicine, agriculture, and environmental protection. To improve the production efficiency of prodigiosin and develop a low-cost biomass carbon source to reduce the fermentation cost, we mutated Serratia marcescens strain isolated previously in our laboratory through atmospheric and room-temperature plasma (ARTP) mutation breeding and obtained a mutant strain RZ 21-6C with a high pigment production and high genetic stability. The fermentation performance analysis of different carbon sources showed that the mutant strain not only significantly improved the conversion of conventional carbon source - sucrose, but also synthesized prodigiosin from xylose and glucose. In particular, the utilization efficiency of xylose was very high. Based on the above characteristics, low-cost biomass carbon source corn stover hydrolysate with xylose as the main component was developed for the production of prodigiosin. The highest concentration of prodigiosin in fed-batch fermentation reached 16.17 g.L^-1, with a production efficiency of 0.12 g.L^-1.h^-1, and a total sugar conversion rate of 20.21%. The transmission electron microscopy (TEM) observation of strains and of cell membrane components and permeability showed significant changes in the physiological state of the mutant strain to facilitate pigment efflux and substrate pumping. Finally, combined with the physiological data and proteomic results, the underlying mechanism of efficient prodigiosin production by RZ 21-6C was explained from the perspective of phenotypic changes, prodigiosin synthesis, membrane transport, glycogen utilization, and primary metabolism. In this study, a S. marcescens RZ 21-6C strain with excellent characteristics was obtained by modern physical mutagenesis for the biosynthesis of prodigiosin using the hydrolysate of corn stover, an agricultural waste, as a fermentation substrate, which provides an important technological support for the renewable biorefinery of prodigiosin bio-based products.