Characterization of nutrient-removing microbial communities in two full-scale WWTP systems using a new qPCR approach

Biological wastewater treatment processes involve very complex microbial communities. Culture-independent molecular methods are feasible tools used to analyze and control the structure of different microbial communities, such as bacterial communities that remove nutrients. Here, we used the gBlocks gene fragments method, a new real-time PCR approach for the development of DNA standards, to quantify total bacterial cells, AOB, NOB, and Archaeal genes at two different WWTPs. PAOs were also quantified using the FISH technique. Our findings highlight a significant improvement in real-time PCR detection for the microorganisms studied. The qPCR and FISH technique applied allowed characterization of the microbial composition of two WWTPs operated as a conventional WWTP and a biological nutrient-removal WWTP. The results revealed a significant difference in the microbial profiles of the WWTPs, with a higher abundance of nitrifying bacterial communities and PAOs in the nutrient removal plant, which were in accordance with operational performance. [Display omitted] •Microbial composition of two WWTPs was characterized using qPCR and FISH techniques.•gBlocks were used as a rapid and easy technique for elaboration of DNA standards.•The log-linear range of DNA standards was improved at least one order of magnitude.•Microbial composition of WWTPs was in accordance with the operational performance.