Metatranscriptomic analysis of lanthanum driven multi-element metabolic regulation in a rare earth tolerant microbial consortium.

The biological functions of rare earth elements (REEs) are gaining increasing attention, however, their systematic regulatory mechanisms regarding the metabolism and biogeochemical cycling of complex soil microbial communities remain unclear. In this study, a highly tolerant and stable microbial consortium (La-T18) was enriched and acclimated from REE-contaminated soil. Combining physiological assays and metatranscriptomics, we systematically analyzed the growth, metabolism, and gene expression responses of this consortium under varying concentrations of lanthanum (La) treatments. The results indicated that the La-T18, dominated by Pseudomonadota, primarily immobilized La through cellular sequestration into a non-desorbable fraction (72%). Physiological analyses revealed that La significantly promoted the growth of the consortium and accelerated carbon source consumption (p < 0.05), whereas La concentrations of 20 μM and above significantly inhibited its nitrification activity. Metatranscriptomic analysis demonstrated that La specifically induced the expression of the REE-dependent methanol dehydrogenase gene (xoxF). Beyond C1 metabolism, La significantly upregulated genes associated with multi-carbon compound degradation, transmembrane transport, and antioxidant stress responses. In contrast, the assimilatory nitrate (nirA) and sulfate reduction (cysNCH) pathways were markedly suppressed. These molecular insights suggest that REEs do more than drive canonical C1 pathways; they reconfigure microbial multi-element biogeochemical cycling and cellular homeostasis, offering a reference for assessing the microecological impacts of REE mining.