Chapter 2 - Bacterial diversity of the rock-water interface in freshwater ecosystem

Abstract

Solid-liquid interfaces are imperative in microbial ecology as the microorganisms attach themselves to the solid substrates and develop to form biofilms. In water bodies, complex combinations of microorganisms named biofilms are formed at the rock-water interface, and most microorganisms on the earth live in such aggregations which are otherwise also known as microbial landscapes. This chapter summarizes the bacterial diversity in rock-water interface in freshwater ecosystems. It explains the attachment of freshwater bacteria to solid surfaces and the sessile bacteria as an important component of microbial populations. The endoliths and epiliths represent the largest reservoir of biodiversity on the planet dominated by Proteobacteria (alpha, beta, and gamma), followed by other phyla including Firmicutes, Bacteroides, and Actinobacteria have been explained in a detailed manner. This chapter further explains the dynamics of epilithic and endolithic microbial mats, their role, and colonization pattern. A brief discussion has been done on the chemolithotropic microbial mats on subsurface and deep granitic rocks showing that the groundwater from profound aquifers in granitic rocks is populated by huge quantities of microorganisms of which sulfate reducing microbes make a huge part. The chapter concludes with a few case studies on some lakes and deep igneous rock aquifers followed by some concluding remarks.