Visualizing Microorganism-Mineral Interaction in the Iberian Pyrite Belt Subsurface: The Acidovorax Case.

Cristina Escudero,Ricardo Amils,Felipe Gómez,Jose M Martínez,Adolfo Del Campo,Carlos Sánchez,Jose R Ares

doi:10.3389/fmicb.2020.572104

Abstract

Despite being considered an extreme environment, several studies have shown that life in the deep subsurface is abundant and diverse. Microorganisms inhabiting these systems live within the rock pores and, therefore, the geochemical and geohydrological characteristics of this matrix may influence the distribution of underground biodiversity. In this study, correlative fluorescence and Raman microscopy (Raman-FISH) was used to analyze the mineralogy associated with the presence of members of the genus Acidovorax, an iron oxidizing microorganisms, in native rock samples of the Iberian Pyrite Belt subsurface. Our results suggest a strong correlation between the presence of Acidovorax genus and pyrite, suggesting that the mineral might greatly influence its subsurface distribution.

Highlights

Interest in deep continental subsurface geomicrobiology has grown in the last decades and led to an increase in the amount of information on these environments
CARD-Fluorescence In Situ Hybridization (FISH) analysis was performed to determine the depths at which Acidovorax genus is present throughout the first 300 meters below surface of the Iberian Pyrite Belt (IPB) column (Figure 1)
Once the Acidovorax colonies were located in the rock samples by fluorescence microscopy, the same area could be analyzed by Confocal Raman Microscopy (CRM) using the slide coordinate system (Figure 3)

Summary

Introduction

Interest in deep continental subsurface geomicrobiology has grown in the last decades and led to an increase in the amount of information on these environments. We know that life in deep continental subterranean environments is widespread, diverse and active (Kieft, 2016; Escudero et al, 2018a; Magnabosco et al, 2018). More in-depth analyses are still needed to better understand the functioning of subsurface ecosystems. One of the main sources of electron donors and acceptors in these oligotrophic ecosystems, could determine which metabolisms are carried out and, which microorganisms can inhabit a certain subsurface micro niche (Jones and Bennett, 2014). Hydrogen produced by water-rock interaction (among others processes) is believed to be one of the principal drivers of subsurface

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Discussion

Conclusion