pH Shaping the Composition of <i>sqhC</i>-Containing Bacterial Communities

:Sediment and tailings samples were collected from sites with a contrasting physicochemical gradient to investigate microbial squalene-hopene cyclase (<i>sqhC</i>) composition and distribution in terrestrial environments. Acidobacteria (66%), Alphaproteobacteria (96%) and Gammaproteobacteria (55%) were found to dominate <i>sqhC</i> communities, respectively, at the acidic Dajiuhu Peatland, the alkaline Heshang Cave and strongly acidic tailings of Tongling copper mine in China. Statistical analysis confirmed that pH was the important factor impacting the geographical distribution of <i>sqhC</i> at phylum level. <i>sqhC</i> gene abundance is comparable at the three sites. However, the total amount of hopanoids in per gram total organic matter content (TOC) is 1.75 times higher in the acidic peatland than that in the alkaline Cave and it is below the detecting limit in tailings of Tongling copper mine, inferring the potential impact of pH in regulating the hopanoid production.