Mixed organic acids as an effective green modifier for enhancing PAH degradation by ZIF-8@ B. subtilis ZL09-26

Although a protective shell based on a metal-organic framework (MOF) can effectively improve the remediation of polycyclic aromatic hydrocarbons (PAHs) by microorganisms, the functional characteristics of the shell are often limited by the surface charge, chemical properties and intrinsic strain characteristics. This study explored the potential of mixed organic acids (MA) as an eco-friendly modifier for zeolite imidazolate framework-8 (ZIF-8), facilitating the formation of a biomimetic mineralized shell around Bacillus subtilis ZL09-26. The addition of MA into the ZIF-8 protective shell was found to stimulate growth and bolster cell viability. Notably, adding MA contribute resulted in a 1.98- fold enhancement of the PHE degradation efficiency. After five cycles of reuse, ZIF-8-MA@ B. subtilis ZL09-26 still maintained almost 90 % of the initial PHE degradation ability. Proteomic analysis revealed a coordinated regulation of multiple metabolic pathways that facilitated PHE uptake and degradation, including central carbon metabolism, direct PHE biodegradation, oxidative phosphorylation, aminoacyl-tRNA biosynthesis, fatty acid biosynthesis, ABC transporters, and the biosynthesis of valine, leucine, isoleucine, and lysine. This work broadens the application potential of biomineralized microorganisms, providing novel strategies for the sustainable bioremediation of xenobiotic pollutants in the environment.