Abstract

Rivers are important ecosystem services providers in southern Chile; however, the microbiology of most rivers are understudied. This is particularly true for phosphorus (P) recycling by bacterial activity. Here, we studied the physicochemical properties, P contents, phosphomonoesterase (Pase) activities, and bacterial Pase genes (phoD, phoC, and phoX) in Chilean river sediments (Imperial and Tolten rivers, Chile) collected in sites with less and more degrees of anthropogenic influence during the summer and winter seasons. The richness, diversity, composition, and predicted function of the bacterial communities were addressed, as well as the spatiotemporal relationships among P-associated parameters and bacterial communities. Our results showed spatiotemporal variations, highlighting higher values of the temperature, conductivity, nutrients (C, N, P), Pase activity, and Pase genes in sediments collected in sites more anthropogenized during summer. In contrast, higher richness, diversity, and abundance of total bacteria were found in sediments collected in winter. The phylum Proteobacteria and heterotrophy were the most relatively abundant bacterial taxa and predicted function, respectively. The differentiation among winter and summer sediments was also revealed and the relationships between bacterial community and P-associated parameters were confirmed. Our analysis also highlighted the positive relationship between Pase genes with Gemmataceae, Xanthomonadaceae, and Chitinophagaceae families, and between Pase activity and Po with Chromatiaceae and Desulfobacteraceae families. This study represents an initial investigation aimed to unravel the compositions and relationships of bacterial communities with P recycling in these sedi-ments, which are threatened by anthropogenic activity (e.g., agriculture, industry, cities, etc.). This information may be used in the design of countermeasures to prevent deterioration of Chilean rivers, which are relevant as ecosystem service providers. (c) 2021 Elsevier B.V. All rights reserved.