Multifunctional bacterial consortium degrading phthalates, promoting plant growth and inhibiting soil-borne...

Microbial consortia having multi-functions including plant growth promotion, against soil-borne pathogens and bioremediation remain extremely scarce. Here, five isolated bacterial strains with different functions were used to construct a synthetic consortium S5. Consortium S5 completely degraded di-n-butyl phthalate (DBP) within 24 h and di(2-ethylhexyl) phthalate (DEHP) within 72 h, and metabolized multiple PAEs and their metabolic intermediates, confirming its strong PAE degradation ability. Strains Gordonia amicalis H3 and Mycobacterium sp. R14 played key roles in PAE degradation although their low relative abundances within consortium S5 by sequencing. Consortium S5 notably promoted plant growth in vitro and vivo with high biomass. Consortium S5 exhibited strong antagonistic activity against tomato Fusarium oxysporum f. sp. lycopersici strain Fol 8 J and distinctly alleviated its stress to tomato plant. Moreover, consortium S5 tolerated wide ranges of temperature, pH and salinity. Interestingly, biochar-immobilized consortium S5 (i.e., BS5) stored at 4 and 30 °C for 30 d exhibited good stability, strong antagonistic activity against F. oxysporum Fol 8 J and proficient PAE degradation. Both free and immobilized consortia enhanced significantly PAE removal from soil with more bioaugmentation effectiveness of BS5 than free consortium S5. High throughput sequencing and qPCR analysis revealed the well colonization of member strains and enrichment of PAE-degrading genes with higher abundances in the soil inoculated with BS5 than consortium S5. These findings on multifunctional consortia highlights their great potential in achieving multiple objectives for bioremediation, promoting plant growth, and against soil-borne pathogens.