Oligotrophic characteristics and genomic analysis of the Rhodoligotrophos defluvii lm1T isolated from activated sludge

Abstract

Oligotrophic conditions have important role in the evolution of life and also the study of ecological status and ecological functions of oligotrophic bacteria in such ecosystems. In this study, the oligotrophic characteristics of the experimental strain Rhodoligotrophos defluvii lm1T (hereinafter referred to as lm1T) isolated from activated sludge were investigated. The results indicated that lm1T was able to grow normally in Luria-Bertani (LB) and diluted LB solid agar plates, demonstrating it to be a facultative oligotrophic bacterium. Research about carbon source and genome analysis revealed that lm1T lacks 6-phosphofructokinase in the glycolysis process, resulting in the inability to convert glucose-6-phosphate to fructose-6-phosphate, which prevented lm1T from utilizing glucose. And in line with that, lm1T can utilize 1,6-diphosphofructose, acetate, propionate, and butyrate to meet its growth requirements. lm1T possesses a wide range of nitrogen sources utilization, including NaNO3, urea, NH4Cl, (NH4)2SO4, peptone, and yeast extract, enabling its adaptation to various complex environments. Additionally, comparative genomic analysis of lm1T and the model strain Rhodoligotrophos appendicifer 120-1T revealed that lm1T had more genes related to degradation metabolism, which aided its adaptation to complex environments.