Correlation between bacterial community structure and performance efficiency of a full-scale wastewater treatment plant

This study aimed at understanding how bacterial communities fluctuate and correlate with wastewater treatment plant (WWTP) efficiency over a ten-month period. Illumina sequencing of 16 s rRNA gene variable regions was performed on genomic DNA extracted from aeration tank samples collected twice a week and analyzed using the Bioinformatics Tool Quantitative Insights into Microbial Ecology 2 (QIIME2). This was done in order to track and relate changes in the bacterial community in the aeration tank to the performance of the plant. The results revealed that the most dominant bacterial phyla present in the aeration tank were Proteobacteria (15 %-40 % of total sequences in all samples), and Bacteroidetes (14 %-41 %) followed by Planctomycetes (2 %-23 %), Patescibacteria (2 %-13 %), Chloroflexi (3 %-12 %), and Nitrospirae (1 %-9 %). Beta analysis revealed clear shifts in the bacterial communities with an overall cyclic pattern that correlated well with the month of the year the aeration tank samples were collected through which samples clustered in groups with samples taken in the same month clustering closer together. Planctomycetes and Bacteroidetes were enriched during the colder, while Chloroflexi and Nitrospirae were enriched during the warmer months. Lastly, it was also found that the efficiency of biological oxygen demand (BOD) and ammonia-N removals were significantly correlated (P < 0.05) with the occurrence of Bdellovibrio bacterial genus and members of Hydrogenophilaceae, respectively. This study is the first to provide this level of temporal resolution on bacterial community fluctuations in a full scale WWTP in the UAE.