Ganga river water quality assessment using combined approaches: physico-chemical parameters and cyanobacterial toxicity detection with special reference to microcystins and molecular characterization of microcystin synthetase (mcy) genes carrying cyanobacteria

Abstract

Water quality assessment relies mostly on physico-chemical based characterization however, eutrophication and climate change advocate the abundance of toxic microcystins (MCs) producing cyanobacteria as emerging bio-indicator. In the present study, a spatial-temporal analysis was carried out at ten sampling sites of Prayagraj and Varanasi during June 2017 and March 2018 to determine the Ganga River water quality using physico-chemical parameters, cyanobacteria diversity, detection of MCs producing strains and MC-LR equivalence. Coliform bacteria, COD, NO 3 -N and phosphate are the signi cant contaminated parameters favoring the growth of putative MCs producing cyanobacteria. National Sanitation Foundation WQI (NSFWQI) indicates water quality, either bad or medium category at sampling points. The morphological analysis con rms the occurrence of diverse cyanobacterial genera such as Microcystis, Anabaena, Oscillatoria, Phormidium etc. PCR ampli cation a rmed the presence of toxic microcystin (mcy) genes in uncultured cyanobacteria at all the sampling sites. The concentration of MC-LR equivalence in water samples by protein phosphatase 1 inhibition assay (PPIA) and high-performance liquid chromatography (HPLC) methods was observed in the range of 23.4-172 ng/L and 13.2-97.5 ng/L respectively which is lower than the harmful exposure limit by World Health Organization (WHO). Ganga isolate 1 was identi ed as Microcystis based on partial 16S rDNA sequence and its toxicity was con rmed due to presence of mcy genes and MCs production potential. These ndings suggest the presence of MCs producers as new emerging parameter to monitor water quality index and identi cation up to species level will be valuable for restoration strategies of river Ganga. Conductivity(mho/cm) 304 293 308 402 374 309 352 293 386 372 273 245 294 304 TSS(mg/L)

Selected Measurement Parameters of Water Quality: Comparative Insight of India and Indonesia

“…There are 4 primary parameters that must be used in determining the class of water use such as BOD, DO, pH, and total coliforms. Practically, the implementation of water quality monitoring in India mostly uses physicochemical parameters, but to ensure that the monitored water is safe for human health and other living things, the calculation of toxic microcystisns (MC) that produce cyanobacteria is used as a bioindicator approach (Kesari et al, 2021). Furthermore, previous studies have proven that cyanobacteria can be used as a major bioindicator of water pollution worldwide (Casero et al, 2019;Mateo et al, 2015); Therefore, the presence of MC in river water can be applied to predict the trophic status of river water.…”

“…Furthermore, previous studies have proven that cyanobacteria can be used as a major bioindicator of water pollution worldwide (Casero et al, 2019;Mateo et al, 2015); Therefore, the presence of MC in river water can be applied to predict the trophic status of river water. In terms of water quality monitoring in Ganga River conducted by Kesari et al (2021), 15 physico-chemical parameters and 7 biological parameters were selected. Those physico-chemical parameters include temperature, pH, conductivity, TSS, TDS, hardness, alkaline, iron, nitrate, COD, phosphate, sulfate, chlorine, DO and BOD.…”

“…The results of the WQI calculation of Ganga River conducted by Kesari, et al, (2021) in Prayagraj showed that in 2017 the river water quality was in the poor category with a WQI score of 46.31, and in 2018 the river water quality was classified as medium with a WQI score. 50.66.…”

“…This also occurs in India as developing country with the second largest population in the world (Ahmad et al, 2020). River in India, especially the Ganga River, has a very important role as water resource to meet human daily needs and become the center of Hindu culture so that many religious activities are carried out on the river (Kesari et al, 2021). On the contrary, that river faces serious water pollution due to the waste of human activities such as domestic, industry and agriculture that are directly discarded into river without treatment (Siddiqui and Pandey, 2019;Dixit et al, 2017).…”

Co-occurrence of microcystin and cylindrospermopsin in hypereutrophic Mahakanadarawa and Nachchaduwa reservoirs

“…MC and its chemical variants are cyclic peptides produced by various species of cyanobacteria such as Anabaena, Anabaenopsis Microcystis, Nostoc, Oscillatoria and Planktothrix in the major orders of cyanobacteria viz. Chroococcales, Oscillatoriales, Nostocales (Nowruzi and Porzani 2021;Kesari et al 2022). MC-producing cyanobacteria are found primarily in freshwaters with a wide geographic and ecological distribution worldwide.…”