Analysis of the microbiota composition and gene expression in a phosphorus accumulating biofilm operating in a novel waste water treatment process

Abstract

The Hias process is a novel biofilm based waste water treatment process designed for phosphorus removal and recovery. The process has also demonstrated significant nitrogen removal potential. The aim of this study was to investigate the microbial composition of the Hias biofilm throughout the reactor and how it relates to its functioning in the process. In addition, the expression of genes involved in nitrogen removal was evaluated as well as whether their expression is correlated with chemical components measured in the waste water. A sample handling method was developed for high quality nucleic acid extraction from the Hias biofilm. 16S rDNA sequencing revealed microbial composition of the biofilm to be stable while species evenness decreased throughout the Hias process. Relative abundance of ammonium oxidising bacteria increased in aerated parts of the Hias reactor while abundance of phosphate accumulating organisms decreased. Real time quantitative PCR showed no correlation between amoA transcript levels and decreasing NH4 concentration.