Endophytic Phthalate-degrading Bacillus subtilis N-1-gfp colonizing in soil-crop system shifted indigenous bacterial community to remove di-n-butyl phthalate

Endophytic bacteria can degrade toxic phthalate (PAEs). Nevertheless, the colonization and function of endo-phytic PAE-degrader in soil-crop system and their association mechanism with indigenous bacteria in PAE removal remain unknown. Here, endophytic PAE-degrader Bacillus subtilis N-1 was marked with green fluores-cent protein gene. Inoculated strain N-1-gfp could well colonize in soil and rice plant exposed to di-n-butyl phthalate (DBP) as directly confirmed by confocal laser scanning microscopy and realtime PCR. Illumina high-throughput sequencing demonstrated that inoculated N-1-gfp shifted indigenous bacterial community in rhizosphere and endosphere of rice plants with significant increasing relative abundance of its affiliating genus Bacillus than non-inoculation. Strain N-1-gfp exhibited efficient DBP degradation with 99.7% removal in culture solutions, and significantly promoted DBP removal in soil-plant system. Strain N-1-gfp colonization help plant enrich specific functional bacteria (e.g., pollutant-degrading bacteria) with significant higher relative abundances and stimulated bacterial activities (e.g., pollutant degradation) compared with non-inoculation. Furthermore, strain N-1-gfp displayed strong interaction with indigenous bacteria for accelerating DBP degradation in soil, decreasing DBP accumulation in plants and promoting plant growth. This is the first report on well colonization of endophytic DBP-degrader Bacillus subtilis in soil-plant system and its bioaugmentation with indigenous bacteria for promoting DBP removal.

Automated summary

Endophytic bacteria Bacillus subtilis N-1 can effectively degrade toxic phthalate, and their colonization and function in soil-crop system have been investigated. The inoculated strain N-1-gfp can colonize in soil and rice plant, resulting in a shift in indigenous bacterial community and increased pollutant degradation. Furthermore, strain N-1-gfp displayed strong interaction with indigenous bacteria for accelerating phthalate degradation, reducing phthalate accumulation in plants, and promoting plant growth.