Bacterial Diversity Of The Consortium With Capacity Of Lignocellulose Degradation And Bacterial Synergy Analysis Based On Macrotranscriptomics

In order to clarify synergetic effect and relationship of bacteria in lignocellulose-degrading bacterial consortium,filter papers and rice stalks were biologically treated using the consortium.Based on the test of degradation characteristics,total DNA and RNA of the consortium at different stages of degradation were selected for high-throughput sequencing of amplicons of bacterial 16 S rRNA genes and high-throughput sequencing of macrotranscriptome.The aim of study was to reveal the succession of bacterial community and synergistic degradation pattern between bacteria during lignocellulose degradation by the consortium.The 12 th hour,72 nd hour and 168 th hour of culture were selected as initial stage,peak stage and final stage of degradation by the test of degradation characteristics.Based on the diversity of bacterial community composition annotated by 16 S rRNA genes,bacteria in the consortium showed different growth trends.With lignocellulose degradation,relative abundance of Brevibacillus and Caloramator decreased gradually.Relative abundance of Clostridium,Bacillus,Geobacillus and Cohnella increased gradually.Relative abundance of Ureibacillus,Tissierella,Epulopiscium was highest in peak stage.Relative abundance of Paenibacillus and Ruminococcus didn't change obviously in each stage.Based on the diversity of bacterial community composition annotated by the macrotranscriptome,transcripts of the consortium at different stages of degradation were mainly derived from the Clostridium,Bacillus,Alkaliphilus,Thermoanaerobacter,Vibrio,Paenibacillus,Parvimonas,Geobacillus,Eubacterium,Caldanaerobacter,Ruminococcus,Acetivibrio,Caldicellulosiruptor,Desulfotomaculum.The Clostridium,Bacillus,Geobacillus,Paenibacillus,and Ruminococcus all dominated mainly in both numbers and coding transcripts.Using the KEGG and EGGNOG databases to analyze functional and metabolic characteristics of consortium at different stages of degradation,it was found that genes involved in the carbohydrates metabolism were very active in the consortium at different stages of degradation,which was associated with a rich enzymes related to carbohydrate metabolism and microbes encode them in the consortium.Using the CAZy database to annotate cellulases and hemicellulases genes of consortium at different stages of degradation,it was found that the AA1 family genes played a role in lignin degradation.The GH5,GH8,GH9,GH10,GH16,GH26,GH27,GH30,GH44,GH48,GH74,GH81,GH101,and GH124 family genes played a role in cellulose degradation during cellulose and hemicellulose degradation to monosaccharides by the consortium.The GH2,GH11,GH39,GH43,GH51,GH53,GH55,GH67,GH113,GH115,GH127,CE2,CE6,CE7,CE8,CE12 and CE15 family genes played a role in hemicellulose degradation.The GH1,GH3,GH4,GH29,GH31,GH35,GH36,GH42,GH50,GH78,GH94,GH95,GH105 and GH116 family genes played a role in oligosaccharide degradation.At the same time,cellulosome domain genes as well as CBMs genes that bind to substrates and assist in degradation had also been found to play an important role during cellulose and hemicellulose degradation.Analysis of bacteria encoding AA,GH and CE genes involved in degradation function revealed that the Brevundimonas mainly encoded AA genes,and it was a major microorganism that degraded lignin.Clostridium,Paenibacillus,Bacillus and Microcystis were all major bacteria that degrade cellulose,hemicellulose,and oligosaccharides.The Clostridium,Paenibacillus,Bacillus,Microcystis and Vibrio mainly encoded GHs and CEs family genes.Using the KEGG database to annotate pathway of cellulose degradation at different stages of degradation,we found that the pathway was complete and most of enzyme genes were annotated.In summary,the consortium was composed of aerobic bacteria,facultative bacteria and anaerobic bacteria.In initial stage of degradation,aerobic bacteria were in a main dominant position in numbers,followed by anaerobic bacteria.From peak stage of degradation to last stage of degradation,anaerobes and facultative bacteria gradually became main dominant bacteria in numbers.However,main dominant bacteria in numbers weren't dominant in function.Functional dominant mainly bacteria encode transcripts in the consortium were all anaerobic or facultative bacteria,and anaerobes accounted for the vast majority.Bacterial community structure of the consortium changed significantly during lignocellulose degradation by the consortium.The carbohydrates metabolism was very active in the consortium at different stages of degradation.Finally,the model of synergistic effect relationship of efficient ligcellulose degradation by bacteria in the consortium was constructed,which linked functional genes and functional bacteria encoding genes,and abstract synergistic relationship of bacteria in the consortium was shown in a graphical and concrete manner.