Water quality assessments and metagenomic analysis of the polluted river Apatlaco, Mexico

The aim of this study is to analyze the water quality parameters and bacterial diversity and thereby understand the effect of water quality on the microbial population structure in the river. The following parameters: total coliforms, chemical oxygen demand, harness, ammonium, nitrite, nitrate, total Kjeldahl nitrogen, dissolved oxygen, total phosphorus, total dissolved solids, and temperature were analyzing along 17 sampling points in the river. The worst levels of pollution were 510 mg/L chemical oxygen demand, 7 mg/L nitrite, 45 mg/L nitrate, 2 mg/L dissolved oxygen, and 756 mg/L of total dissolved solids. Whole metagenome shotgun sequencing was performed at 4 key points along the river (P1,P7,P10 and P17), the first point had clean water and the other points were polluted, as a result of this pollution, the structure of microbial communities along the river have changed. Proteobacteria and Bacteroidetes were the most representative phyla with a relative abundance of 57 and 43% respectively for P1, 82 and 15% for P7, 69 and 27% for P10 and 87 and 10% for the last point P17. P1 is rich in microorganism such as Limnohabitans a planktonic bacterium very common in freshwater ecosystems. However, in P7, P10 and P17 are rich in opportunistic pathogens such as Acinetobacter Arcobacter and Myroides that endangers the health of around 1.6 million people which live around the area. These results elucidate the influence of the pollution on the microbial community and the likely effects on the health of the people around.