Spatial distribution of Bacteroidota, Myxococcota, Spirochaetota and Verrucomicrobiota in sediment of the urbanized Kanawha River (West Virginia)

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Andrielle Larissa Kemajou Tchamba, Flor De Maria Guerrero-Toledo, Jesus Emmanuel Chavarria-Palma, Olushola Deborah Awoyemi, Ifeoma R. Ugwuanyi, Amir Hass and David Huber, Department of Biology, Gus R. Douglass Institute, West Virginia State University, Institute, WV

Background/Question/Methods
Non-point source runoff from impervious surfaces and point sources like WWTP in urban areas are potential sources of anthropogenic pollutants of river ecosystems. The river sediment microbiome is susceptible to local and regional changes in land use. Similarities in land use practices across urban areas can cause biodiversity homogenization. Nevertheless, little is known about the effect of urbanization on the spatial variation of freshwater microbes. This study was aimed at investigating microbial diversity and distribution in sediment from urbanized and industrialized sections of a river and its relationship to chemical geography. Our study area was 125 mi2 of urbanized and industrialized sections of Kanawha River watershed (60% forested, 34% developed). Replicate sediment samples were collected from 0-5 and 5-10 cm layers of sediment from five widely-spaced locations along a 15 km stretch of the river. Total DNA was extracted with the PowerMax soil kit and 16S rRNA gene diversity was sequenced to determine microbiome composition. 20 chemical variables were measured using ICP-OES, ion chromatography and Aurora Total Organic Carbon Analyzer. 16S rRNA sequences were analyzed with QIIME2 and Silva 138 Database. Correlation analysis of the microbiomes and environmental variables were performed in R.
Results/Conclusions
Among the most abundant microbial phyla surveyed were Bacteroidota (13.1%), Spirochaetota (4.65%), Verrucomicrobiota (3.47%) and Myxococcota (1.71%). Ordination analysis of environmental variables revealed distinct chemical profiles among sampling locations shaped by some nonpoint source pollutants such as Zn, Cu, SO42-, NO3-, NH4+, Fe and Mg. Multivariate ordination analysis revealed a geographical pattern in the distribution of the river sediment microbiome with Bacteroidota and Verrucomicrobiota exhibiting a wider distribution among locations whereas Myxococcota and Spirochaetota showed a more localized distribution. ANOSIM showed significant differences in the abundance of all 4 phyla between locations and considerable variation between sediment layers. Phylogenetic diversity analysis showed differentiation between the locations and sediment layers. Spirochaetota showed the highest correlation with other phyla and environmental variables whereas Myxococcota showed the opposite correlation pattern. Furthermore, Zn (an urbanization proxy) was positively correlated with Spirochaetota but negatively with Bacteroidota. In conclusion, these four phyla showed different distribution patterns in urban watershed sediment which indicates that habitat filtering is still present in the urbanized sediment ecosystem. Funding by USDA-2019-38821-29065.