Research On Important Microbal Population And Corresponding Functional Genes In Industrial Anaerobic Granular Sludge

Methanogens are considered to be important microbial populations in anaerobic granular sludge. and mcrA,mtr and F420 are the important functional genes in methanogens encoding some unique coenzymes. Methanogenic community and functional genes mentioned above in anaerobic granular sludge samples from full-scale UASB bioreactors treating avermactin or starch wastewater were investigated by PCR-DGGE and FISH analysis. The diversity of methanogenic community, the phylogenetic relationship of dominant methanogeinc populations and the relative abundance of methanogens were discussed and compared when 16S rRNA gene or functional gene was used as target gene. The inhibitory effects of antibiotics on methane-producing capacity of sludge samples were also explored. The results were shown as follows.The diversitv indices of methanogenic communitv calculated from DGGE band patterns. including Shannon diversity index. Margalef richness index and Berger-Parker dominance index. were no difference between mcrA gene-based and 16S rRNA gene-based PCR products. although their DGGE band patterns were different. implying that the diversity analysis of methanogenic community based on mcrA genes was consistent with 16S rRNA gene. The phylogenetic analysis of dominant methanogenic populations based on these two target genes also showed resemble and methanobacteriales and methanosarcinales were determined to be the main orders of methanogenic populations in anaerobic granular sludge sample treating avermectin wastewater. Then it could be conclude that mcrA gene and 16S rRNA gene could be alternative for methanogenic community analysis. although the difference in phylogenetic analysis suggested simultaneously some group-specific of these two target genes.The distribution forms of methanogens in FISH analysis based on different target genes were almost identical for one kind of sludge sample except some difference in hybridization areas. The average relative abundance of methanogens based on hybridization area was in the following order:mcrA20mg·L-1). The inhibitory effect of erythromycin on methanogens in the sludge sample treating avermectin wastewater seemed weaker. due to similar structure of erythromycin with avermectin probably.