Microorganisms for Consolidated 2nd Generation Biorefining

In the last decades, lignocellulosic biomass has attracted enormous interest (owing to its large availability and low cost) as feedstock for fermentative production of fuels and other commodity chemicals. However, the innate complexity and high recalcitrance to biodegradation of this biomass has significantly slowed progress towards economically viable biorefining processes. No natural cellulolytic microorganism isolated so far can efficiently produce industrially relevant products, hence industrial fermentation of lignocellulose has traditionally been performed through expensive multiple-bioreactor processes. Barriers towards the development of cost-sustainable lignocellulose biorefining process include: the need for costly biomass pre-treatment which may additionally generate compounds that inhibit fermenting microorganisms; dependence on high loads of expensive cellulase mixtures for biomass saccharification; issues in efficient co-fermentation of hexose and pentose sugars (e.g. because of carbon catabolite repression).

Intense research effort has been made to fix current issues of lignocellulose fermentation processes, e.g. through isolation of new microbial strains, understanding their metabolism, study of the structure and function of cellulase systems, metabolic and protein engineering, and optimization of the fermentation process. Ideally, the development of the so-called consolidated bioprocessing, namely single-pot fermentation, would dramatically reduce process cost and provide a cost-sustainable technology for the production of biofuels, bioplastics and other high-value chemicals. The present Research Topic intends to capture the state of the art of these studies. The papers given in this contribution should demonstrate the importance of their findings in the development of more efficient lignocellulose degradation and/or production of industrially relevant chemicals thus helping progress towards more consolidated and cost-efficient 2nd generation biorefining. This Research Topic will encompass studies from the lab bench until moving forward to the future biotechnological applications.

This article collection welcomes the submission of high-quality recent studies (including original research, review, methods, mini review, and perspective papers) covering (but not limited to) the following themes:

· Microbial metabolism of cellulose and other components of the lignocellulosic biomass

· Development of models of the metabolism of cellulolytic microorganisms or other microorganisms which are relevant for 2nd generation biorefining

· Metabolic engineering aimed at developing microorganisms for 2nd generation biorefining processes

· Development of genetic tools for manipulation of microorganisms with potential in lignocellulose fermentation

· Development of natural and recombinant microbial consortia for efficient fermentation of lignocellulosic biomass

· Production of cellulases and other enzymes for biomass pre-treatment/saccharification

· Isolation and characterization of new microbial strains with potential for 2nd generation biorefinery processes.