Recent Development of Extremophilic Bacteria and Their Application in Biorefinery.

Daochen Zhu,Wasiu Adewale Adebisi,Fiaz Ahmad,Blessing Danso,Sivasamy Sethupathy,Jianzhong Sun

doi:10.3389/fbioe.2020.00483

Abstract

The biorefining technology for biofuels and chemicals from lignocellulosic biomass has made great progress in the world. However, mobilization of laboratory research toward industrial setup needs to meet a series of criteria, including the selection of appropriate pretreatment technology, breakthrough in enzyme screening, pathway optimization, and production technology, etc. Extremophiles play an important role in biorefinery by providing novel metabolic pathways and catalytically stable/robust enzymes that are able to act as biocatalysts under harsh industrial conditions on their own. This review summarizes the potential application of thermophilic, psychrophilic alkaliphilic, acidophilic, and halophilic bacteria and extremozymes in the pretreatment, saccharification, fermentation, and lignin valorization process. Besides, the latest studies on the engineering bacteria of extremophiles using metabolic engineering and synthetic biology technologies for high-efficiency biofuel production are also introduced. Furthermore, this review explores the comprehensive application potential of extremophiles and extremozymes in biorefinery, which is partly due to their specificity and efficiency, and points out the necessity of accelerating the commercialization of extremozymes.

Highlights

Extremophiles are a group of organisms that thrive under extreme environmental conditions (e.g., high/low temperature, pH, salinity, and pressure) that most life forms find it difficult to survive in
Extremophiles are a group of organisms that thrive under extreme environmental conditions that most life forms find it difficult to survive in
The “omics” technologies could resolve the bottleneck of research on unculturable microorganisms and find new high activity enzymes and metabolic pathways that can be used in biorefinery, which is the driving force to achieve sustainable biofuel production

Summary

Introduction

Extremophiles are a group of organisms that thrive under extreme environmental conditions (e.g., high/low temperature, pH, salinity, and pressure) that most life forms find it difficult to survive in. It has been reported that a variety of thermophilic bacteria and their secreted enzymes have great application potential in bioenergy production and anaerobic fermentation, and these include Caldicellulosiruptor bescii, Geobacillus proteiniphilus, TABLE 1 | Applications of extremophiles and extremozymes in industry. Enzymes from alkaliphiles with high thermostability, alkaline activity, and substrate specificity have added more advantage for biofuels production under harsh industrial conditions (Annamalai et al, 2016).

Results

Conclusion