Growth and genetic analysis of Pseudomonas BT1 in a high-thiourea environment reveals the mechanisms by which it restores the ability to remove ammonia nitrogen from wastewater

Abstract

ABSTRACT Thiourea is widely present in wastewater and can inhibit the nitrification process, inducing the collapse of the nitrification system in sewage treatment plants. Pseudomonas BT1 can restore the ammonia nitrogen removal ability of wastewater treatment processes in which the nitrification system due to thiourea. However, the genetic mechanisms for BT1 are still unclear. In this study, we reported the first genome assembly for Pseudomonas BT1, which has a genome size of 5,576,102 bp and 5,115 predicted genes. Complete C and S metabolic cycles were identified in its genome, and some intersecting intermediate products were found in these cycles. BT1 can grow well and remove ammonia nitrogen at different thiourea concentrations, but it showed a better removal ability in high-thiourea environments. The longest gene activity stage of BT1 was observed in the high-thiourea environments by RNA sequencing, and genes related to maintaining intracellular copper homeostasis were highly expressed during the S metabolism process, which may be the key to restoring the ammonia nitrogen removal ability. Enzymes detected during the N and S cycles showed that BT1 reacts with thiourea to produce hydrogen but not sulphate, suggesting that BT1 may have genes that are involved in thiourea hydrolysis. In conclusion, the high-quality assembly of BT1 provides a valuable resource for analyzing its biological process and molecular mechanisms for thiourea metabolism. BT1 shows great application potential for the removal of thiourea from sewage treatment plants.