Metatranscriptomes taken during aerobic granule formation

The active microbial community and the gene expression was studied during the formation of aerobic granule in a sequencing batch reactor using de novo metatranscriptomics. The influence of the phosphate concentration, from high to low, was also studied. Four metatranscriptomics samples were taken at day 13 (mean particle size around 172 um, COD/P ratio of 12), day 26 (300 um, COD/P ratio of 12), day 103 (1000 um, COD/P ratio of 12) and day 182 (1000 um, COD/P ratio of 200). In the first part of the experiment, high concentration of phosphate, the biomass aggregated to form round shape granules along side with the enrichment of Candidatus Accumulibacter. In the second part of the experiment, when reducing the phosphate concentration, Propionivibrio became the most abundant microorganism and the granule remained round and bigger than 1000 um.