Identification Of Sphingomonas Sp.nov. From Human Lung And Research On Its Degradation Characteristics For Polycyclic Aromatic Hydrocarbons

Backgroud: Polycyclic aromatic hydrocarbons(PAHs)are one of the main environmental carcinogens leading to the high incidence of lung cancer in Xuanwei.Early exploration on lung microorganisms of lung cancer in Xuanwei found that the abundance of bacteria that can degrade PAHs increased.(the National Natural Science Foundation of China,82272980).A new Sphingomonas species was isolated from the lung of Xuanwei lung cancer patients with PAHs pollution background.Objective:In this study,the suspected new species of sphingomonas isolated was numbered LC-1,The strain LC-1 was identified by multiphase classification,phylogenetic tree,and genetic characteristics analysis to determine the taxonomic status of the new species.The whole genome sequencing and functional annotation analysis of strain LC-1 were performed.To investigate the degradation ability of strain LC-1 to different PAHs.Methods: 1.Dilution-plate method was used to isolate bacteria from alveolar lavage fluid of lung cancer patients in Xuanwei,Yunnan.The strain LC-1 is classified and identified by multiphase classification that phase contrast microscope,transmission electron microscope,physiological and biochemical characteristics,chemical characteristics and gene characteristics.2.The whole genome of strain LC-1 was sequenced,and functional annotation of KEGG,GO,GOC,NR database was conducted for encoding gene sequences.3.Degradation characteristics of 4 PAHs,such as phenanthrene,chrysene,benzo [a]pyrene and benzo[ghi]perylene,were studied by the strain of LC-1.Results: 1.Classification and identification of strain LC-1: Gram-negative Brevibacterium,aerobic bacterium,no fimbriae,no flagellum,no spores,no movement,about 2.5×1.0μm in size;The optimal growth conditions were 30℃,p H6,0.5%Na Cl;Phylogenetic analysis based on 16 S r RNA gene sequence showed that strain LC-1 had the highest similarity with Sphingomonas sanguinis NRBC113637(98%);the average nucleotide sequence(ANI)values of LC-1 and other model strains were all less than 95%,and the digital DNA-DNA hybridization(d DDH)values were all less than 70%.The main ubiquinone of strain LC-1 was Q-10(48.13%).The polar lipids included DPG,PG,PE,SGL and PC,and 2 unknown lipids,1 unknown amino lipid,1 unknown phospholipid and 1 unknown glycolipid were also detected.The main fatty acid content was Summed Feature 8(C18: 1ω7c and/or C18: 1ω6c)67.96%;C16: 0 12.51%;C14: 0 2OH 9.55%.Spermine accounted for the majority of polyamines.The main cell amino acid was meso-DAP;the main cell wall sugars included rhamnose(Rha)and ribose(rib).The G + C content of LC-1 DNA was 65.65mol%.Based on the above results,the strain of LC-1 was identified as a new species of Sphingomonas,The proposed will name Sphingomonas Xuanweipulmo sp.nov,the type strain was LC-1T.2.The results of genome sequencing showed that the genome size of the strain was4.14 Mb,with 3843 predicted coding genes and 76 RNA genes(3 r RNA and 54 t RNA).Four metabolic pathways were annotated by KEGG:degradation of aromatic compounds(ko01220),naphthalene(ko00626),chlorocyclohexane and chlorobenol(ko00361),and polycyclic aromatic hydrocarbons(ko00624).By analyzing related genes,the degradation genes of the strain were preliminarily identified,among which24 genes were related to the degradation of aromatic compounds(ko01220),8 genes were related to naphthalene degradation(ko00626),6 genes were related to the degradation of chlorocyclohexane and chlorobenzene(ko00361)and 2 genes were related to the PAHs degradation(ko00624).3.Under the substrate concentration of 10mg/L,the degradation rate of LC-1 with phenanthrene as the sole carbon source was 55%,chrysene as the sole carbon source was 38%,and benzo [a] pyrene as the sole carbon source was 20% in 6 days;benzo[ghi] perylene could not be metabolized as the only carbon source or energy source.Conclusion: 1.A Sphingomonas strain named LC-1 is isolated from lung of lung cancer patients in Xuanwei,Yunnan.According to 16 S r RNA gene phylogenetic tree analysis,physiological,biochemical,chemical,and genotypic characteristics,strain LC-1 was identified as a new species of Sphingomonas.The proposed will name Sphingomonas Xuanweipulmo sp.nov,the type strain was LC-1T.2.Genomic function analysis indicated that Sphingomonas Xuanweipulmo LC-1T had the potential to degrade polycyclic aromatic hydrocarbons.3.Sphingomonas Xuanweipulmo LC-1T can be grown using phenanthrene,chrysene and benzo [a] pyrene as the only carbon sources.