| This study provides the basis for the development of an innovative method for the fast and cost-effective assessment of water quality based on the aquatic prokaryotic microbiome. Phylogenetic analyses conducted on the metagenomic data revealed that the dominant prokaryotic phyla detected in the 19 samples are similar to the ones typically detected in freshwater environments. Microbial diversity indices showed that all 2012 samples were characterized by a low biodiversity, while 2013 samples were characterized by a higher diversity, which is likely the result of different meteorological conditions in 2012 and 2013.;Clustering analysis and principal component analysis (PCA) were conducted to investigate the relationships between the relative abundance of the prokaryotic phyla and water quality parameters. The results showed that the samples collected from the same sites in different years cluster well together when compared based on the water quality parameters. On the contrary, the samples collected in 2012 made a separate group of cluster and same is true for 2013 samples when compared based on the prokaryotic phyla. These observations suggest a larger temporal variation of the microbial communities than the physico-chemical parameters of the water.;PCA focusing on prokaryotic communities showed that Proteobacteria and Bacteroides phyla, including aerobic heterotrophic, fast growing bacteria --- referred to as copiotrophic or 'r-type' organisms ---, cluster together. On the other hand, the other phyla, including mostly anaerobic and/or autotrophic, slow growing bacteria - referred to as oligotropic or 'K-type' organisms ---, form a rather distinct cluster.;The dependence of the prokaryotic relative abundance on the water quality parameters for the 19 samples was then interrogated using RDA. As showed by PCA investigations, the r-type phyla cluster together and correlate with high alkalinity and conductivity. On the contrary, the K-type phyla cluster together and correlate collectively with sulfate and nitrate. As expected, the copiotrophic, fast-growing, r-type phyla also correlate with the stream samples, while the oligotrophic, slow-growing, K-type phyla correlate better with spring, cave, and mine samples.;This study provides the basis for the development of an innovative method for the fast and cost-effective assessment of water quality based on the prokaryotic microbiome. |
