Study On Degradation Of Phenol By Sphingomonas Paucimobilis At Genomics And Transcriptomics Levels

Phenol is a very important industrial raw material as well as a toxic pollutant.It is widely distributed in the environment and has careinogenic,teratogenic,and mutagenic effects.According to reports,a large number of microorganisms are capable in phenol degradation.Among them,Sphingomonas has attracted much attention due to its unique metabolic mechanism,a variety of degradation genes and highly active degrading enzymes.Therefore,study on the metabolic pathways of phenol by microorganisms is also ofimportance for pollutant control and regulation in the prevention.In the paper,S.paucimobilis was selected to study the metabolic pathway and tolerance range of phenol,the results are as follows:(1)The whole-genome sequencing of S.paucimobilis was performed by the use of Illumina Hiseq,and the results showed that the total length was 4994934 bp,the content of GC base was 41.937%.There were 329 scaffolds,533 contig,332 tandem repcats,166 tRNAand 6 rRNA.The coding sequence sequences accounted for 82.15%of the total length of the genome.The main molecular function of S.paucimobilis is DNA binding and ATP binding;the main components of the cell membrane are the inner membrane and cytoplasm;the biological processes are mainly redox processes,regulating transport,transmembrane transport and metabolic processes.The metabolism of xenobiotic substances is diverse and can degrade a variety of polycyclic aromatic hydrocarbons.The core genes are catA and ALW03_RS05345.(2)A concentration gradient experiment was performed on S.paucimobilis to determine its tolerance range,and then simulated water samples under different water quality conditions were prepared to simulate the repair effect.The results showed that S.paucimobilis has a maximum tolerable concentration of 800 mg/L of phenol within 24 h.In the experiment of remediation of simulated water samples,S.paucimobilis has a higher degradation efficiency for simulated phenol-polluted wastewater prepared in actual water bodies.It shows that S.paucimobilis is more suitable for in situ restoration.(3)The transcriptome sequencing of phenol degradation by S.paucimobilis was performed using RNA-seq technology.34.42 Gb of Clean Data was obtained.233 genes were differentially expressed under phenol stress,of which 129 were up-regulated,yet 104 were down-regulatcd.Up-regulated genes include degrading enzyme genes,fatty acid production-related genes,protein transport-related genes,and glutathione genes.It shows that bacteria accelerate the production of related degrading enzymes under phenol stress,and at the same time accelerate their own anti-oxidation and detoxification functions,so as to avoid damage to organelles.By accelerating the export of LPS protein,which has a penetrating effect on toxic substances,the permeability of cells is reduced,and at the same time,the cell membrane is reinforced to prevent toxic substances from entering the cell.(4)According to the results of transcriptomics,it is speculated that the metabolic pathway of phenol should be the hydroxylation of phenol to catechol,followed by o-ring opening and catechol 2,3 double addition under the action of catechol 1,2 dioxygenase.The meta position is opened under the action of oxygenase.However,the ortho-position open loop is the main one,and the meta-position open loop is a supplement.The paper has 20 pictures,14 tables,and 64 references.