Biodesulfurization of thiosulfate by a Pseudomonas strain PSP1 and the investigation of underlying metabolic mechanisms.

Abstract

The increasing public expectations for good air quality have necessitated the development of biodeodorization technology. Among different malodorous pollutants, H2S has attracted extensive attention and diverse biodesulfurization technology has been developed for efficient H2S removal. In this study, a novel heterotrophic Pseudomonas strain, PSP1, was isolated from biogas slurry and its biodesulfurization ability was investigated. Culture conditions of 30°C and 200rpm were determined as the optimal for both cell growth and thiosulfate conversion. Under such conditions, the highest OD600 value was observed as 6.74 and 50mM thiosulfate within 10h. PSP1 was found to convert thiosulfate to sulfane which could be decomposed into elemental sulfur and therefore achieved desulfurization. However, this process was relatively weak as more than 60% thiosulfate was converted into soluble tetrathionate. The whole genome sequencing and functional annotation identified the genes in PSP1 associated with sulfur metabolism and the RT-qPCR analysis quantified the expression level of corresponding genes. The expression level of tsdA, which was responsible for tetrathionate production, was around 60 folds higher than genes for sulfane production (e.g. TST1, cysI). Further research would focus on the enhancement of sulfane production pathway through metabolic engineering tools.