Distinct Microbial Communities in the Soils, Waters, and Speleothems of a Hyperalkaline Cave System

Abstract

Cave and karst systems represent some of the least studied extreme environments on the planet. Caves are in most cases characterized by extreme nutrient deficiency and utter darkness (Dong et al., 2020), characteristics quite inhospitable to life. However, understanding the karst critical zone (Chen et al., 2018) is of fundamental importance to vast numbers of the global population who rely on karst aquifers for fresh drinking water supplies (Stevanovic, 2019). Possibly the least well-established connections within karst and cave science revolve around the role of microbial communities within karst, their sources, abundance, community structure and their ability to adapt and even thrive in cave environments (Engel, 2010). It is possible that microbial communities play a central role in the karst aquifer system; their utilisation and consumption of key nutrients (C, N, S, and P) may help to balance the anthropogenic increase in nutrient loads to many karst environments. With microbes holding such a