Comparative Analysis of Microbial Diversity Across Temperature Gradients in Hot Springs From Yellowstone and Iceland.

Peter T Podar,Snædís H Björnsdóttir,Mircea Podar,Zamin Yang

doi:10.3389/fmicb.2020.01625

Peter T Podar, Snædís H Björnsdóttir + Show 2 more

Open Access

https://doi.org/10.3389/fmicb.2020.01625

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Abstract

Geothermal hot springs are a natural setting to study microbial adaptation to a wide range of temperatures reaching up to boiling. Temperature gradients lead to distinct microbial communities that inhabit their optimum niches. We sampled three alkaline, high temperature (80–100°C) hot springs in Yellowstone and Iceland that had cooling outflows and whose microbial communities had not been studied previously. The microbial composition in sediments and mats was determined by DNA sequencing of rRNA gene amplicons. Over three dozen phyla of Archaea and Bacteria were identified, representing over 1700 distinct organisms. We observed a significant non-linear reduction in the number of microbial taxa as the temperature increased from warm (38°C) to boiling. At high taxonomic levels, the community structure was similar between the Yellowstone and Iceland hot springs. We identified potential endemism at the genus level, especially in thermophilic phototrophs, which may have been potentially driven by distinct environmental conditions and dispersal limitations.

Highlights

Archaea and Bacteria inhabit nearly every environment on Earth, including many that are inhospitable to multicellular life, such as hot springs
Extreme temperature and pH values have been shown to have the largest contribution in restricting microbial diversity, the magnitude of their effects are dependent on the hot spring and were influenced by geochemistry and other environmental factors (MeyerDombard et al, 2011; Hamilton et al, 2012; Cole et al, 2013; Wang et al, 2013; Sharp et al, 2014; Chiriac et al, 2017; Merkel et al, 2017; Power et al, 2018; Tang et al, 2018; Zhang et al, 2018)
The hypothesis that microbes in general have a high dispersal rate, that would homogenize genetic variations that may arise as result of local ecological and evolutionary events, Microbial Diversity Across Temperature Gradients has been challenged by studies of microbes in geothermal hot springs (Whitaker et al, 2003; Papke and Ward, 2004)

Summary

Introduction

Archaea and Bacteria inhabit nearly every environment on Earth, including many that are inhospitable to multicellular life, such as hot springs. While microbial communities that inhabit geochemically similar hot springs on different continents are expected to be physiologically and taxonomically similar, some of the individual species may evolve as endemic populations, similar to plants and animals on distant islands. This has been demonstrated by comparing thermophilic Synechococcus (Bacteria) and Sulfolobus (Archaea) in hot springs from North America, Europe and Asia (Papke et al, 2003; Whitaker et al, 2003; Becraft et al, 2020)

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