Integrated physiological characteristics and temporal transcriptomic analysis reveal the molecular mechanism of Pseudomonas aeruginosa degrading diesel stimulated by extracellular metabolites of euglena

Abstract

Diesel pollution poses a serious threat to the ecological environment. Adding environmentally friendly biostimulants to enhance the metabolic function of indigenous microorganisms is currently a preferred strategy to improve remediation efficiency. In this study, cell morphology, physiological characteristics, and molecular level analysis of Pseudomonas aeruginosa LNR1, which was screened from oil-contaminated soil and has a diesel degradation effect, were investigated to elucidate the stimulus mechanisms by which extracellular metabolites of euglena (EME) acting as a biostimulant. The electron microscopy results indicated that EME could restore the bacterial morphological structure. Physiological analysis revealed that EME not only promoted bacterial proliferation and the secretion of extracellular proteins and polysaccharides, but also enhanced electron transfer activity and ATP content. Genomic indicated that strain LNR1 had the potential to degrade diesel efficiently. Transcriptome analysis showed that the stimulating effect of EME on strain LNR1 was distinction at different degradation time points. The initial degradation stage mainly affected the decomposition of polysaccharide and detoxification, while the active degradation stage mainly induced biochemical metabolic processes, such as amino acids and organic substrates. In particular, the expression of a series of functional genes related to pollutant emulsion adsorption, transmembrane transport, signal transduction (quorum sensing, two-component system, chemotactic system) and degradation genes was up-regulated. This study comprehensively revealed the mechanisms by which the biostimulant EME enhanced diesel degradation in strain LNR1 from multiple perspectives. It provides theoretical guidance for the practical application of EME in bioremediation, offering significant societal and economic benefits.