Endophytic Bacillus megaterium Reshapes Rhizosphere Processes to Promote Phthalate Esters Dissipation

Abstract Phthalate esters (PAEs) contaminate agricultural soils, yet how introduced endophytes reshape rhizosphere processes and influence PAE dissipation remains unclear. We investigated the PAE-degrading endophyte Bacillus megaterium YJB3 in choysum (Brassica parachinensis L.) grown in soils spiked with dibutyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP). YJB3 alleviated PAE-induced inhibition of lateral-root development and enhanced PAE dissipation, particularly DEHP dissipation under low contamination. Soil zymography revealed YJB3-associated shifts in the spatial distributions of β-glucosidase and xylanase activities around roots, with an increased proportion of β-glucosidase hotspots within the total enzyme-active area under PAE stress. Across the rhizosphere, rhizoplane, and endosphere, YJB3 inoculation was associated with changes in bacterial community composition and higher relative abundances of several genera, including Streptomyces, Nocardioides, and Kitasatospora. Collectively, YJB3-associated enhancement of PAE dissipation coincided with changes in root development, rhizosphere enzyme activities, and root-associated bacterial communities, highlighting the potential of endophytes for remediation of PAE-contaminated soils.