Mechanism of phenanthrene degradation by the halophilic Pelagerythrobacter sp. N7

PAHs has shown worldwide accumulation and causes a significant environmental problem especially in saline and hypersaline environments. Moderately halophilic bacteria could be useful for the bioremediation of PAH pollution in hypersaline environments. Pelagerythrobacter sp. N7 was isolated from the PAH-degrading consortium 5H, which was enriched from mixed saline soil samples collected in Shanxi Province, China. 16S rRNA in the genomic DNA revealed that strain N7 belonged to Pelagerythrobacter. Strain N7 exhibited a high tolerance to a wide range of salinities (1-10%) and was highly efficient under neutral to weak alkaline conditions (pH 6-9). The whole genome of strain N7 was sequenced and analyzed, revealing an abundance of catabolic genes. Using the whole genome information, we conducted preliminary research on key enzymes and gene clusters involved in the upstream and downstream PAH degradation pathways of strain N7, thereby inferring its degradation pathway for phenanthrene and naphthalene. This study adds to our understanding of PAH degradation in hypersaline environments and, for the first time, identifies a Pelagerythrobacter with PAH-degrading capability. Strain N7, with its high efficiency in phenanthrene degradation, represents a promising resource for the bioremediation of PAHs in hypersaline environments.