Monitoring of ribosomal RNA in the supernatant of activated sludge

Abstract

 The authors developed a protocol to analyze 16S rRNA in supernatant of activated sludge by reverse transcription—polymerase chain reaction (RT-PCR), and monitored a cycle of a laboratory activated sludge sequencing batch reactor (SBR) with the developed method. When RT-PCR was performed with filtered activated sludge supernatant with 25 thermal cycles, products were obtained, and were confirmed to originate from RNA, not DNA. The supernatant of the SBR was analyzed by the developed method in combination with pyrosequencing. Some of the operational taxonomic units (OTUs) were observed to increase or decrease significantly, while others remained stable. It was thought that the fluctuation of the OTUs were specific phenomena. While the real meanings of the fluctuations of rRNA in the supernatant are not yet fully understood, the authors developed here a new approach to investigate microbial ecosystems in activated sludge.