The Study Of Methane-bacteria In Activated Sludge

1. The present paper is aimed at exploring the diversity of methanotrophs from sludge which exists in drying reed bed. The PCR-based denaturing gradient gel electrophoresis(PCR-DGGE) technologies have been used to determine the variation of the methanotrophs community structures in sludge which in different periods and from disparate drying beds. Clustering analysis results for the fingerprint of DGGE indicates the similarity of different samples. The Shano-Wiener index were calculated as 2.03、1.09、1.87、2.04、1.36、 1.95,1.59、 1.17、 1.92 and the Pielou index were 0.99、 0.97、 0.95,0.97、0.98、 0.99,0.95、 0.97、0.99 for the reed bed sludge samples with the changes in different months from first unit to the third unit. Namely, with the change of the different months, the index of the first unit drying bed decreased but the other units increased. The comparison of affinity was obtained from the sequences of the post-sequencing, and then analyzed the succession for the methane oxides bacteria community of the sludge samples combining with the advantages of the species changing. The results showed that PCR-DGGE technologies were effective methods to analyze methanotrophic communities. Cluster analysis of the fingerprint of DGGE implied that methanotrophs communities were highly similarity for the different drying reed beds at the same period. However, there were some differences among the which in the same reed bed for different period, the dominant species of bacteria changed with the different growth stages of reed and extension of time of the sludge stabilization. Based on the sequences and phylogenetic analysis, uncultured type 1 methanotrophs was the dominant bacteria in sludge of drying reed bed, indicating that the reed bed with snorkels could accelerate the methane oxidation and help to reduce emission of the methane2. Isolate and screen type Ⅱ methanotroph from second unit sludge drying reed bed. Agar plate dilution method was used to carry out isolation, and the taxonomic position was determined using a polyphasic approach. The results showed that strain W5 grew well on media tested, the colonies were pink. Based on phylogenetic, morphological analyses demonstrated that strain W5 belong to the genus Methylobacter.3. A methanogen strain C5 was isolated from third unit sludge drying bed, by anaerobic screening technique. The strain C5 emit blue-green fluorescence when observed by fluorogenic microscope. Sequence analysis of the 16S rDNA genes of strain C5 and Methanosarcina revealed that the similarity reaches to 99%. Phylogenetic analysis and morphological characteristics show that strain W5 belongs to Mehanosarcina...