Effects Of Goethite/Hematite On Microbial Metabolic Pathways And Major Genes In Mutual Oxidation And Methanogenesis

In the process of organic anaerobic methanogenesis,short-chain fatty acid mutual oxidation is the key link of organic matter degradation.At present,little is known about the microbial communities and functions involved in this process.It is found that conductive materials can promote mutual oxidation and methanogenesis.In this paper,the carbon source propionic acid and butyric acid were repeatedly added,and the goethite/hematite was used as the conductive material.The 16S rRNA high-throughput sequencing technology was used to analyze the microbial community changes in different methanogenesis cycles,and the method of real-time PCR and metagenomic sequencing was used.Propionic acid and butyric acid interact with each other in oxidative metabolic pathways and in the methanogenic process.The main conclusions are as follows:?1?With the extension of the methanogenesis cycle,the species composition of the microbial community is more diverse.The bacteria are from the initial AUTHM 297and T78,followed by propionate oxidizing bacteria or butyrate oxidizing bacteria,and the dominant microorganisms have been enriched in the sixth methanogenic cycle.The dominant bacteria in the propionate and butyrate groups were Syntrophobacter and Syntrophomonas,respectively,and the methanogenic archaea were Methanothrix,Methanoculleus and Methanosarcina.?2?Through the degradation test of substrate,it can be seen that the addition of needle/hematite can promote the reaction of propionic acid to acetic acid.The effect of hematite is the most obvious,followed by goethite,and the control group without iron oxide is the slowest;quantitative PCR experiment bac 16s The gene copy number of rRNA bacteria showed little change in total bacteria,all within the same order of magnitude 10⁸.Quantitative PCR and metagenomic methods determined that the content of mcr gene was goethite>hematite>control group;The degradation is through the methylmalonyl-coenzyme and the Malonate Semialdehyde pathway.The needle/hematite has little effect on the metabolic pathway of propionic acid;the yield and rate of CH₄ is known as hematite>goethite,and the methanogenic gene is relatively abundant.The degree is goethite>hematite,piliA gene abundance goethite group>hematite group,OmcS gene abundance hematite group>goethite group,which indicates that DIET promotion may exist in the hematite group The rate of methanogenesis.?3?Through substrate degradation experiments,it was found that the addition of needle/hematite promoted the reaction of butyric acid to acetic acid.The effect of goethite was the most obvious,followed by hematite,and the control group without iron oxide was the slowest;quantitative PCR experiment 16s rRNA The gene copy number of bacteria showed little change in total bacteria,all within the same order of magnitude 10⁸.Quantitative PCR and metagenomic methods determined that the content of mcr gene was hematite group>goethite group>control group;macrogen group could know Acid degradation is through the oxidation and oxidation of?to the succinic acid pathway;from the yield and rate of CH₄,the iron ore group>hematite group,and the relative abundance of methanogenic genes is hematite group>goethite group,OmcS gene In the abundance hematite group>goethite group,there may be DIET in the goethite group to promote the rate of methanogenesis.