Microbial induced phosphate precipitation accelerate lead mineralization to alleviate nucleotide metabolism inhibition and alter Penicillium oxalicum's adaptive cellular machinery

Microbial-induced phosphate (P) precipitation (MIPP) based on P-solubilizing microorganisms (PSM) is regarded as a promising approach to bioimmobilize environmental lead (Pb). Nevertheless, the underlying changes of Pb2+ biotoxicity in PSM during MIPP process were rarely discussed. The current study explored the Pb2+ immobili-zation and metabolic changes in PSM Penicillium oxalicum postexposure to Pb2+ and/or tricalcium phosphate (TCP). TCP addition significantly increased soluble P concentrations, accelerated extracellular Pb mineralization, and improved antioxidative enzyme activities in P. oxalicum during MIPP process. Secondary Pb2+ biomineral-ization products were measured as hydroxypyromorphite [Pb-10(PO4)(6)(OH)(2)]. Using untargeted metabolomic and transcriptomics, we found that Pb2+ exposure stimulated the membrane integrity deterioration and nucleotide metabolism obstruction of P. oxalicum. Correspondingly, P. oxalicum could produce higher levels of gamma- aminobutyric acid (GABA) to enhance the adaptive cellular machineries under Pb2+ stress. While the MIPP process improved extracellular Pb2+ mineralization, consequently alleviating the nucleotide metabolism inhi-bition and membrane deterioration. Multi-omics results suggested that GABA degradation pathway was stimu-lated for arginine biosynthesis and TCA cycle after Pb2+ mineralization. These results provided new biomolecular information underlying the Pb2+ exposure biotoxicities to microorganisms in MIPP before the application of this approach in environmental Pb2+ remediation.

Automated summary

This study investigated the metabolic changes in PSM Penicillium oxalicum postexposure to Pb2+ and/or tricalcium phosphate (TCP). The addition of TCP improved Pb mineralization, antioxidative enzyme activities, and metabolic response in P. oxalicum. The results provided new insights into the biotoxicity of Pb2+ exposure to microorganisms in the MIPP process.