Oxidative Stress and Metal Tolerance in Extreme Acidophiles

Abstract

Acidophiles are life-forms that grow preferentially in natural or man-made environments where the pH is well below seven. Together with other categories of extremophiles, they have greatly expanded our knowledge of the diversity of life, our understanding on how microorganisms can adapt to seemingly hostile situations, and provided scenarios for the possibility that life-forms may be found outside of our solar system.Written by experts in their field, this important volume provides a comprehensive account of acidophilic microbiology from fundamental to applied aspects. The seventeen chapters are arranged in five sections, each dealing with a specific area. The first section looks at the challenges faced by life-forms that grow in extremely acidic environments and how they adapt to meet these challenges. The next section describes the physiological and phylogenetic diversities of acidophilic microorganisms including archaea, bacteria and eukaryotes. Section three covers acidophile community dynamics, quorum sensing and the formation of biofilms. The next section deals with the various omic technologies that are used to study acidophiles including genomic and metagenomic studies, proteomic-, mobilomic-and metabolomic-focused research. The final section considers the ways in which acidophiles are used in established and emerging biotechnologies and describes why these fascinating microorganisms are considered potential candidates for life on other solar bodies, such as Mars, and beyond.This up-to-date and comprehensive book will be indispensable for environmental scientists and microbiologists and is a recommended acquisition for all microbiology libraries. Chapter 1. Acidophile Microbiology in Space and Time (D. Barrie Johnson and Raquel Quatrini) Chapter 2. Energy Acquisition in Low pH Environments (Wolfgang Nitschke and Violaine Bonnefoy) Chapter 3. Adaptation to Extreme Acidity and Osmotic Stress

Deciphering the Role of Multiple Thioredoxin Fold Proteins of Leptospirillum sp. in Oxidative Stress Tolerance

“…Exposure to ferric ions and diamide provides two models of oxidative stress induction [18], although they present noteworthy differences. While diamide triggers disulfide stress, ferric ions have a more direct oxidative effect that leads to their reduction and the consequent generation of ferrous ions, as well as the induction of Fenton chemistry, which in turn facilitates the generation of highly harmful radical species [17]. Additionally, oxidative stress was induced in this work with ferric iron in E. coli by exposure for 15 min and further growth was evaluated in fresh medium.…”

“…is an autotrophic obligate acidophilic bacterium that catalyzes dissimilatory Fe(II) oxidation. It serves as a model bacterium to elucidate the mechanisms used by acidophilic microorganisms to thrive under highly oxidative conditions [16][17][18][19]. Thirteen tfp genes (formerly trx) coding for predicted TFPs have been identified in Leptospirillum spp.…”

Cobalamin Protection against Oxidative Stress in the Acidophilic Iron-oxidizing Bacterium Leptospirillum Group II CF-1

“…Acidic bioleaching environments are considered as highly oxidative where microorganisms are exposed to elevated concentrations of ROS ( Cárdenas et al, 2012 ; Ferrer et al, 2016b ). Thus, oxidative stress represents one of the greatest selective pressures imposed on acidophilic microorganisms.…”

“…These data illustrate that iron-oxidizing and most likely other acidophilic microorganisms are exposed to severe oxidizing conditions that have a negative effect for the cell, and the mechanisms for protection against oxidative stress are thus essential for adaptation and survival in these environments. Although some research has been conducted in this area ( Ferrer et al, 2016b ), the mechanisms involved in anti-oxidative protection in acidophilic microorganisms are not fully understood.…”

Reconstruction of the Metabolic Potential of Acidophilic Sideroxydans Strains from the Metagenome of an Microaerophilic Enrichment Culture of Acidophilic Iron-Oxidizing Bacteria from a Pilot Plant for the Treatment of Acid Mine Drainage Reveals Metabolic Versatility and Adaptation to Life at Low pH

“…Moreover, life in a typical AMD environment also means increased cellular damage caused by, for instance, higher rates of oxygen radical formation due to the high concentrations of redox active metals (in particular iron). Therefore, the genomes of acidophiles typically encode numerous mechanisms for the detoxification of reactive oxygen species (ROS, see Ferrer et al, 2016) and the repair of damaged biomolecules (e.g., genomic DNA itself). However, a detailed analysis of these aspects was seen as beyond the remit of this article, though an initial screening of the metagenomic sequence information indicates that the acidophilic Sideroxydans strains also encode the genetic potential for ROS detoxification and DNA repair.…”