A Proposed Cross-Feeding Model of Phenanthrene Degradation by Constructed Halophilic Consortium NOMA

The accumulation of polycyclic aromatic hydrocarbons (PAHs) in saline environments poses a threat to ecological security; however, the elimination of PAHs from saline environments is difficult. In this study, a constructed microbial consortium, designated NOMA, was constructed from Novosphingobium sp. J3 and Martelella sp. E4 via a "bottom-up" method. Consortium NOMA degraded phenanthrene within 7 days at 5% salinity and retained phenanthrene-degradation activity across the tested salinity, pH, and Cd²⁺ gradients (pH values of 5-10, salinities of 1-20%, and Cd²⁺ concentrations of 0-50 mg/L). PAH-degrading genes in both strains were annotated based on the genomic information. Based on the genomic information and intermediate detection, a cross-feeding model of the phenanthrene degradation process by consortium NOMA was proposed. Strain J3 was responsible for the upstream degradation of phenanthrene, and strain E4 promoted multiple downstream degradation pathways to increase the rate of intermediate transfer. Genome-scale metabolic model (GSMM) predictions suggested a potential interspecies cross-feeding mechanism: J3 supplies upstream aromatic intermediates, whereas E4 provides complementary nutritional and cofactor-related support to J3. This study deepens the understanding of the cross-feeding pattern of PAHs in saline environments and provides a biological resource for the bioremediation of PAH under saline and cadmium stress conditions.