Reactive oxygen species-scavenging system is involved in l-amino acid oxidase accumulation in sp. B3.

To date, the mechanisms underlying the flavoprotein l-amino acid oxidase (LAAO) accumulation in cells remain unclear. In this study, using LAAO-producer spp. as model organisms, we found that the cell biomass is negatively associated with LAAO accumulation, whereas the LAAO accumulation is positively associated with the reactive oxygen species (ROS)-scavenging capability. The expression levels of ROS-scavenging-associated genes were up-regulated with LAAO accumulation in cells, which is presumably due to the requirement for the removal of LAAO-induced ROS. Exogenous HO exposure experiment supported that the ROS-scavenging system is associated with LAAO accumulation in . All these observations indicate that ROS-scavenging capacity determines LAAO accumulation in bacterial cells. Our results shed a light on understanding the mechanism underlying controlling and adapting to LAAO accumulation in . Besides, our findings are critical to the improvement of heterologous expression of active LAAO in the future.