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.
Haoze Lu, Yilong Wen, Lin Wang et al.· Microorganisms· 0 citations
Owing to the high osmotic pressure, the degradation of high-molecular-weight polycyclic aromatic hydrocarbons (HMW-PAHs) in saline environments is quite difficult, leading to a scarcity of research on halophilic PAH-degrading bacteria. In this study, a halophilic synthetic consortium, PES, comprising Pelagerythrobacter sp. N7 and Salinicola sp. A11, was constructed on the basis of the bottom-up strategy. The syntrophic network for pyrene degradation by the consortium PES was investigated on the basis of genomic sequencing, functional gene annotation and expression, intermediates detection and bioemulsifier synthesis analysis. Consortium PES completely degraded 50 mg/L pyrene at 5% salinity in 10 days. Neither of strain N7 or strain A11 was identified able to complete degrade pyrene alone. Among which, strain N7 was responsible primarily for the upstream degradation of pyrene with a slow degradation rate and a low degradation efficiency. Intermediate 4,5-dicarboxyphenanthrene was detected highly accumulated in the pyrene degradation process by strain N7. Strain A11 exhibits no direct pyrene-degrading capability. Combined with the results from bioinformatic analysis and RT-PCR, strain A11 was proposed to supplies a candidate 4,5-dicarboxyphenanthrene decarboxylase to cooperate with strain N7 for complete pyrene degradation. Meanwhile, strain A11 was predicted able to produce bioemulsifier, further improving the pyrene degradation efficiency of PES consortia. Genes encoding gentisate 1,2-dioxygenase in strain N7, catechol 1,2-dioxygenase in strain N7 and A11 were detected highly expressed in pyrene degradation process. To our knowledge, this is the first study in which a syntrophic network of HMW-PAH degradation by a halophilic synthetic consortium was proposed, and 4,5-dicarboxyphenanthrene was identified as the key intermediate during pyrene syntrophic degradation. The halophilic synthetic consortium, PES, exhibited good environmental tolerance, providing an important theoretical basis and valuable microbial resources for the removal of PAHs from saline environments.
Yilong Wen, Haoze Lu, Lin Wang et al.· Frontiers in Microbiology· 0 citations