The Characteristic Of The Microbial Community In The Low-temperature Methanogenic Conditions

This paper were mainly concerned in biological characteristics of enrichmenting samples at different periods and the changes of bacterium group structure.The inoculum was the soil from Namuco Lake and Ruoergai.The sample was carried out under methanogenic enrichment culture in laboratory conditions at 15℃.Measuring indicators include methane and volatile acid content.Technology is mainly DGGE. We also isolated two bacteria of Clostridium and one archeobacterium of Methanosarcina from Namco soil, studied the physiological characteristics and phylogenetic position of the two strains.The results were as follows: (1) Compared the original sample with the sample of manual intervention, community structure appeared differences and reproducibility. The diversity of bacteria of the sample of Sichuan Ruoergai was rich. The diversity of archaea of the sample of Namco was rich(.2)The organic matter content of Sichuan Ruoergai was more than Namco's.Ruoergai'methane production was more than Namco's. The speed of methane production of Ruoergai was faster than Namco. Methane production and acetate metabolism was positive, negative correlation with incubation time and the organic matter content.In the methanogenic process, accompanied by the accumulation of propionic acid and butyric acid. (3) Strain P4-1 could degrade p-toluene sulfonate in the present of yeast. It was significant for strain P4-1 to be utilized in the wastewater treatment.Cells were Gram-positive, spore-forming. Its growth temperature was between 13 and 40℃(optimum at 37℃). pH value was at range of 5.0 to 10.0 (optimum at 7.5-8.0). The presence of NaCl was 0%-5%. Strain P4-1 could metabolize many carbohydrates as carbon sources, including glucose, melibiose and mannitol. Metabolites of glucose were acetate, butyrate, propionate, CO2, and little H2. Based on 16S rDNA studies, strain P4-1 was most close to Clostridium lituseburense DSM 797(M59107) with 98.7% similarity.(4) N-1 strains isolated from soil of Nam Co Lake. N-1 strains belonging to Methanosarcina (Methanosarcina mazei) (sequence similarity 98.1%), were small coccus , 1.6-2.7μm, and extremely strict anaerobic.The strain N-1 use of H2/CO2, acetic acid and trimethylamine as the growth substrate. Its growth temperature was 13-40℃, the optimum growth temperature was 35℃. Optimal NaCl concentration was 0-0.4%. pH value was at range of 6.0-8.5 (optimum at 7.0-7.2.).The stain N-1 was sensitive to ampicillin. Rumen extract can stimulate the growth of strain N-1.