| In view of the gradual depletion of unsustainable fossil fuels such as petroleum,the human community is in serious need of new sustainable energy.Lignocellulose can capture solar energy that enables the storage of energy in the form of biomass.Decomposition of the lignocellulosic biomass into saccharides is achieved by physical and chemical pretreatment,follow by exposureing to enzymes from biomass-degrading organisms.The simple sugar can be subsequently converted into fuels by microorganisms.Therefore,lignocellulose becomes the prime candidate of biofuel production.Widely distributed and a variety of lignocellulose-degrading organism are remained to discover and utilize,however,there are rarely bioinformatics research of lignocellulose-decomposition microbes in different environment.In order to isolate lignocellulosic bacteria and find important enzyme and pathway of lignocellulose degradation from its genome,the study was designed to isolate aerobic lignocellulosic bacteria from the soil and rotten leaves,and cellulose was used as the sole carbon source to isolate strains with high cellulose enzyme activities,genomics and transcriptomics were used to study the gene fuction and metabolism pathways.Twelve strains of efficient cellulose degradation bacteria were isolated from sampling sites using dilution-plate method for primary and secondary screening cultures.Via pre-measurement of cellulose-degrading activities,the strain J1 was defined as the optimal strain.It had yellow,round-shape,neat edge colony and was a Gram-negative bacteium.It was identified as Pseudoxanthomonas sp.strain J1 according to the result of biochemical characteristics and 16S rRNA sequencing analysis.The peak value of endocellullase,filter paper enzyme activity and ?-glucosidase in enzyme production fermentation medium were 0.39,0.18 and 0.11 IUˇml-1,respectively.The fermentation condition such as,culture temperature,pH,carbon source and nitrogen source of strain J1 were preliminarily optimized by single factor control method.Consequently,the optimal condition of strain J1 to produce endocellullase were pH 7.5,28?,the optimal carbon source was sucrose and the optimal nitrogen source was yeast extract powder,while the endocellullase value could up to 0.62 IUˇml-1.The optimize of fermentation condition may be an reference for further study of strain J1.In genomic level,the complete genome of strain J1 was sequenced using MiSeq platform and assembled in Bbioinformantics Center in Nanjing Agriculture University.The genome of strain J1 had a single closed circular chromosome with 3.98 million bases,and the complete genome had been deposited in GenBank under the accession no.CP011144.The genome was submitted to bioinformatics software and databases for annotation,gene functional identification and genome feature analysis on COG databases,CAZy databases and so on.Strain J1 was predicted to have 44 kinds of glycoside hydrolase from 26 varied glycoside hydrolase families,the result of comparative genomes of three Pseudoxanthomonas bacteria showed that only it had the GH1 GH30 and CBM6 which were deletion in other two Pseudoxanthomonas bacteria.It was shown that strain J1 had advantages in cellulose degradation.Furthermore,prediction of lignin decomposition enzyme genes and the KEGG Automatic Annotation Server(KAAS)metabolism pathway revealed strain J1 had a few of lignin degradation enzyme coding genes,and strain J1 could convert cellulose to ethanol.The study isolated and screened Pseudoxanthomonas sp.strain J1 which had high performance of lignocellulose degradation activity with many key enzyme genes.It could be a candidate for utilizing cellulose to produce bioethanol,as well as a microoganism resource for lignocellulose degradation. |
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