As shown in our recent study, boron-doped diamond anodes have been proven to effectively eliminate most of the analyzed micropollutants (such as pharmaceuticals, drugs, and their metabolites) and bacteria in wastewaters from different Slovak and Czech wastewater treatment plants (WWTPs) (Mackulak et al, 2020). Assessing and control of the microbiological quality of effluent water released from WWTPs are of considerable environmental importance because of its impact on receiving waterways, the environment, and the health of humans and animals.
In this work, we show the application of MiniON, a portable nanopore sequencer, to evaluate total and living microbiota in environmental samples - effluent water samples from domestic WWTP, as well as the efficiency of boron-doped diamond electrodes in microbiological safety control of effluent water. The composition of total and active (living) microbial community of effluent water from the domestic WWTP was identified using DNA and cDNA as the template for amplification of 16S rRNA and 28S rRNA genes, subsequently sequenced by MinION nanopore sequencer. Among all the bacterial genera that have been identified by sequencing, the majority represents genus Flavobacterium, which is typically found in the aquatic environment and some species of this genus are freshwater fish pathogens. The other most frequent bacterial genus identified was Pseudomonas. Sequencing of products corresponding to the region of 28S rRNA revealed that the most common yeast/micromycetes genera were Saitoella, Ogataea, Schizosaccharomyces, and Pneumocystis, of which the presence of the last genus is of particular interest since its representative P. carinii may induce Pneumocystis pneumonia, mainly in immunocompromised people. Boron-doped diamond electrodes were applied to samples of effluent water from domestic WWTPs analyzed by the above-mentioned molecular biology approaches, and their efficacy in eliminating active microbiota was confirmed after 30 minutes of treatment. There was no RNA, an indicator of a living microbial community, detected in the samples. These results show the usability of BDD electrodes for control of the microbiological safety of water released from domestic WWTPs.
This work was supported by the research grant APVV-16-0124.
Mackuľak T., Medvecká E., Vojs Staňová A., Brandeburová P., Grabic R., Golovko O., Marton M., Bodík I., Medveďová A., Gál M,, Planý M., Kromka A., Špalková V., Škulcová A., Horáková I., Vojs M. (2020) Boron doped diamond electrode – the elimination of psychoactive drugs and resistant bacteria from wastewater, Vacuum 171. 108957 (doi: 10.1016/j.vacuum.2019.108957).