Isolation and identification of Alcaligenes faecalis W2-3 with high-yield production of dimethyl disulfide.

Dimethyl disulfide (DMDS) is an important volatile organic sulfur compound with diverse applications and substantial demand in the chemical, agricultural, and food industries. The challenges associated with their chemical synthesis have spurred exploration of biological synthesis as an alternative route. Nevertheless, there is limited research on the biosynthesis of DMDS, and the yield remains low. In this study, strain W2-3, exhibiting high DMDS production, was isolated from aged tobacco leaves collected in Hubei Province, China. Based on morphological characteristics, 16S rRNA gene sequencing and phylogenetic analysis, the strain was identified as Alcaligenes faecalis. Through single-factor experimental methods, an initial pH of 7 and temperature ranging from 19.5 to 30 °C were demonstrated to be the optimal fermentation conditions for DMDS production. Under these optimized conditions, the maximum yield of DMDS reached 213.49 mg/L, which was a 1.34-fold increase from the pre-optimization yield of 159.86 mg/L. Moreover, optimization of sulfur sources and concentrations showed that increasing methionine concentration led to higher DMDS production. Under sufficient Met conditions, W2-3 achieved a peak of 2440.71 mg/L DMDS, representing an increase of 11.43-fold compared to the control group without methionine supplementation. This yield significantly surpassed the highest yield reported in the literature (40.06 mg/L) by 60.93-fold, establishing a new record for the highest yield currently known. This study identifies A. faecalis W2-3 as a promising microbial chassis for the biosynthesis of DMDS, characterized by a high yield and strong temperature adaptability. It offers insights into the metabolic pathways and fermentation conditions for industrial-scale DMDS production. As the first systematic optimization research aimed at enhancing DMDS production, it fills a gap in the literature. Our findings pave the way for sustainable and efficient DMDS biosynthesis, with significant implications for promoting its application in agriculture, industry, and environmental management.