Reactive oxygen species-scavenging system is involved in L-amino acid oxidase accumulation in Pseudoalteromonas 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 Pseudoalteromonas 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 Pseudoalteromonas cells, which is presumably due to the requirement for the removal of LAAO-induced ROS. Exogenous H2O2 exposure experiment supported that the ROS-scavenging system is associated with LAAO accumulation in Pseudoalteromonas. 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 Pseudoalteromonas. Besides, our findings are critical to the improvement of heterologous expression of active LAAO in the future.