Discovery Of Novel Accumulibacter Clades And The Niche Differentiation Of Different Accumulibacter Groups

Enhanced biological phosphorus removal is a highly efficient phosphorus removal method based on the accumulation of a large number of polyphosphate particles in the cell.Accumulibacter is considered to be the organism with the most important function of phosphorus accumulation in the process of biological phosphorus removal,but it has not been obtained in the laboratory for any of the pure strains.There are at least 14 groups of known Accumulibacter,however,except for a small amount of metabolic characteristics such as nitrate respiration,little is known about the niche differentiation of different groups of Accumulibacter.In the course of research on the enhanced biological phosphorus removal reactor,it was found that many different groups Accumulibacter with high abundance existed in our reactor,which provides an important prerequisite for the study of metabolic characteristics and niche differentiation of different groups.A metagenomic and metatranscriptome analysis based on high-throughput sequencing techniques was performed on the sludge with different groups and high abundance of Accumulibacter.At the same time,cultivate the above-mentioned sludge with different carbon sources,oxygen,and whether it contains a denitrification process,then detect changes of flora in sludges.Several conclusions are obtained through the above experiments:1)Through the PPK1 gene and metagenomic sequencing analysis,we found that there are at least 7 groups of Accumulibacter in the reactor,and got 9 high quality genomes,and 3 of them are groups that have not yet been described.2)The clade IIC Accumulibacter and clade IG Accumulibacter were found to be enriched in reactors with propionate and acetate as the main carbon sources,respectively,but the latter enrichment effect may be related to the inoculum itself.3)Take the expression quantity of the core genes with significant expressing changes during aerobic and anaerobic phases,and the gene expression quantity of the four Accumulibacter in all metabolic pathways during anaerobic and aerobic stages as the references,the metabolism patterns of different groups of Accumulibacter are related to their systematic relationship.4)The expression of FtsZ gene was used as a potential marker to screen for genes with synchronous expression characteristics of cell division.This study was based on the discussion of the differences in the metabolism and enrichment conditions of different clades of Accumulibacter in the same system,demonstrating the physiological characteristics of different clades of Accumulibacter,suggesting differences in core metabolism between different clades,as well as provides an important basis for enriching and eventually separating specific Accumulibacter.