Extremophiles, a Nifty Tool to Face Environmental Pollution: From Exploitation of Metabolism to Genome Engineering

Abstract

Extremophiles are microorganisms that populate habitats considered inhospitable from an anthropocentric point of view and are able to tolerate harsh conditions such as high temperatures, extreme pHs, high concentrations of salts, toxic organic substances, and/or heavy metals. These microorganisms have been broadly studied in the last 30 years and represent precious sources of biomolecules and bioprocesses for many biotechnological applications; in this context, scientific efforts have been focused on the employment of extremophilic microbes and their metabolic pathways to develop biomonitoring and bioremediation strategies to face environmental pollution, as well as to improve biorefineries for the conversion of biomasses into various chemical compounds. This review gives an overview on the peculiar metabolic features of certain extremophilic microorganisms, with a main focus on thermophiles, which make them attractive for biotechnological applications in the field of environmental remediation; moreover, it sheds light on updated genetic systems (also those based on the CRISPR-Cas tool), which expand the potentialities of these microorganisms to be genetically manipulated for various biotechnological purposes.

Industrial Biotechnology Based on Enzymes From Extreme Environments

“…Culture-dependent approaches have led to discovery of numerous extremozymes, especially hydrolases (amylase, protease, cellulase, lipase) ( Ferrer et al, 2007 ). The increased prevalence of whole genome sequencing allowed for sequencing of extremophilic genomes and cloning and characterization of putative extremozymes ( Elleuche et al, 2014 ; Suriya et al, 2016 ; Gallo et al, 2021 ).…”

A New Strategy for As(V) Biosensing Based on the Inhibition of the Phosphatase Activity of the Arsenate Reductase from Thermus thermophilus

“…Attention has also been devoted to the employment of extremozymes as sources of stable biomolecules [ 25 , 26 , 27 ]. For example, thermozymes from thermophilic microorganisms are active at high temperatures and in several harsh conditions, such as high concentrations of heavy metals, salts, and low pH [ 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. In recent times, the development of arsenic biosensors that measure arsenic through enzymatic inhibition has been described.…”

A Hyperthermoactive-Cas9 Editing Tool Reveals the Role of a Unique Arsenite Methyltransferase in the Arsenic Resistance System of Thermus thermophilus HB27

“…Arsenic resistance genes ( ars ) include genes encoding efflux transporters, redox enzymes, methyltransferases, transcriptional repressors, and biosynthetic pathways for arsenosugars and arsenolipids ( 2 , 3 ). The identification and characterization of these pathways have attracted the attention of fundamental, evolutionary, and biotechnological research ( 4 – 6 ).…”