Bacteria-functionalized biochar promotes phthalate degradation and limits uptake in lettuce (Lactuca sativa L.)

The widespread use of plastics has led to the release of phthalic acid esters (PAEs), which pose risks to ecosystems and human health due to their persistence and bioaccumulation. This study evaluated biochar (BC) with immobilized bacteria as a remediation strategy for PAEs-contaminated agricultural soils. Biochar enhanced microbial activity and supported PAEs degradation. Bacillus subtilis showed the lowest metabolic activity, while Gordonia phthalatica, Patulibacter brassicae, and a mixed inoculum achieved ~70 % degradation efficiency. Indigenous soil microbes effectively degraded low molecular weight PAEs (72-75 %), but less efficiently targeted high molecular weight ones (54-68 %). Lettuce grown in treated soils showed no PAEs degradation products, suggesting effective containment and minimal plant translocation. Monomethyl phthalate was the primary biodegradation intermediate. These results highlight the potential of biochar combined with microbial consortia as a dual-function solution: adsorption and biodegradation, for removing phthalates from agricultural soil.