Functional endophytic organic fertilizer alleviates phthalates burden and promotes vegetable growth with the assistance of indigenous Sphingomonas

Phthalates (PAEs) have become one of the main pollutants threatening the safety and quality of vegetable production. Application of bio-organic soil amendments is a promising approach to eliminate the pollutants and improve the vegetable quality. In the present study, we constructed a functional endophytic organic fertilizer (EOF) with a PAEs degrading endophyte Bacillus subtilis strain HB-T2, which had the ability to eliminate PAEs both inside the vegetables and soil. A pot experiment was conducted to investigate the effect of EOF on PAEs degradation, rhizosphere microbiota, vegetable quality and soil fertility, the results were also compared to chemical fertilizer (CF), organic fertilizer (OF, sterilized EOF) treatments. The EOF containing HB-T2 significantly increased the elimination of PAEs in soil (up to 70%) and vegetables (up to 50%). Both OF and EOF treatments significantly (P < 0.05) increased soil fertility and enzyme activities compared to the chemical fertilizer treatment. The EOF treatment had the highest elimination rate of PAEs in soil and vegetables. The correlation analysis showed that the degradation of PAEs was related to the increase of the dominant rhizosphere bacteria, especially sphingomonas. The efficiency of EOF was also evaluated under practical condition. The biomass (fresh weight) and the quality of the vegetables were significantly improved and the human dietary risks were significantly reduced.