Physico-chemical and microbiological analysis of the Loopspruit River, North West Province: A metagenomic approach

Water quality affected by polluted surface runoff from agricultural settings, storm-water as well as sewage from urban locations, and mining in the North West Province are reasons for concern. Similar situations may exist in areas elsewhere that have similar water issues and impacts. This study aimed to evaluate the water quality of the Loopspruit River by analysing the physico-chemical and microbiological parameters of the water. Bacterial diversity was the highest in less polluted areas of the Loopspruit River. Dominating at all the sites tested were Proteobacteria, followed by Bacteroidetes, Cyanobacteria, Actinobacteria and Verrucomicrobia. Predicted metagenome analysis revealed a correlation between the physico-chemical parameters and observed taxonomic units (OTU). Temperature had a negative correlation with Patescibacteria, Nanoarchaeaeota and Firmicutes (p < 0.05). The negative correlation was strongest with Patescibacteria. Sulphate had a strong correlation with Fusobacteria (p < 0.05). There was also evidence of faecal and agricultural pollution. Analysing and visually representing the water quality of the Loopspruit River demonstrated the value of combining physico-chemical, microbiology and geospatial data for an overview of understanding the potential environmental health risks. Such data could potentially be used for management strategies. HIGHLIGHTS Nutrient and faecal pollution from various sources impact water quality.; Diversity indices and an abundance of bacteria that are impacted by physico-chemical parameters.; Agricultural and sewage pollution impact levels of nitrates (fertilizer).; Network analysis highlights the impacts of nutrients on bacterial diversity.; Call for integrated water quality management to protect a peri-urban river system.;