Spatial Metagenomics of Three Geothermal Sites in Pisciarelli Hot Spring Focusing on the Biochemical Resources of the Microbial Consortia.

Roberta Iacono,Nicola Curci,Beatrice Cobucci-Ponzano,Luisa Maurelli,Andrea Strazzulli,Marco Moracci,Federica De Lise

doi:10.3390/molecules25174023

Abstract

Terrestrial hot springs are of great interest to the general public and to scientists alike due to their unique and extreme conditions. These have been sought out by geochemists, astrobiologists, and microbiologists around the globe who are interested in their chemical properties, which provide a strong selective pressure on local microorganisms. Drivers of microbial community composition in these springs include temperature, pH, in-situ chemistry, and biogeography. Microbes in these communities have evolved strategies to thrive in these conditions by converting hot spring chemicals and organic matter into cellular energy. Following our previous metagenomic analysis of Pisciarelli hot springs (Naples, Italy), we report here the comparative metagenomic study of three novel sites, formed in Pisciarelli as result of recent geothermal activity. This study adds comprehensive information about phylogenetic diversity within Pisciarelli hot springs by peeking into possible mechanisms of adaptation to biogeochemical cycles, and high applicative potential of the entire set of genes involved in the carbohydrate metabolism in this environment (CAZome). This site is an excellent model for the study of biodiversity on Earth and biosignature identification, and for the study of the origin and limits of life.

Highlights

Extreme environments such as hot springs are of great interest as a source of novel extremophilic microorganisms, enzymes, and metabolic pathways essential for the microbial survival in extreme conditions [1]
We demonstrated that even sites that have been consistently sampled for decades are still largely unexplored in terms of microbial diversity and of their extremozymes
The aim of this study is to explore the microbial communities populating three sites of the Pisciarelli hot springs (40◦ 490 45.100 N; 14◦ 80 49.400 E), named Site A, Site B, and Site C (Figure 1A) and investigate their differences in terms biodiversity and potential source of enzymes

Summary

Introduction

Extreme environments such as hot springs are of great interest as a source of novel extremophilic microorganisms, enzymes, and metabolic pathways essential for the microbial survival in extreme conditions [1]. Extremophiles are known to thrive in diverse extreme conditions, such as high or low temperatures, high salinity, acidic and alkaline pH values, and high radiation [2]. They can tolerate these conditions but require the latter for survival. Exploring the diversity of extremophiles and understanding their mechanisms of adaptation [3] permit us to expand our notions of the potential habitable environments able to sustain life beyond Earth [4]. Research on extremophiles and their enzymes (extremozymes) has reshaped our understanding of the origin and evolution of life [5] and the potential for life on other planetary

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