Abstract
In a sustainable society based on circular economy, the use of waste lignocellulosic biomass (LB) as feedstock for biorefineries is a promising solution, since LB is the world’s most abundant renewable and non-edible raw material. LB is available as a by-product from agricultural and forestry processes, and its main components are cellulose, hemicellulose, and lignin. Following suitable physical, enzymatic, and chemical steps, the different fractions can be processed and/or converted to value-added products such as fuels and biochemicals used in several branches of industry through the implementation of the biorefinery concept. Upon hydrolysis, the carbohydrate-rich fraction may comprise several simple sugars (e.g., glucose, xylose, arabinose, and mannose) that can then be fed to fermentation units. Unlike pentoses, glucose and other hexoses are readily processed by microorganisms. Some wild-type and genetically modified bacteria can metabolize xylose through three different main pathways of metabolism: xylose isomerase pathway, oxidoreductase pathway, and non-phosphorylative pathway (including Weimberg and Dahms pathways). Two of the commercially interesting intermediates of these pathways are xylitol and xylonic acid, which can accumulate in the medium either through manipulation of the culture conditions or through genetic modification of the bacteria. This paper provides a state-of-the art perspective regarding the current knowledge on xylose transport and metabolism in bacteria as well as envisaged strategies to further increase xylose conversion into valuable products.
Highlights
The human population has become an undisputable force that has a deteriorating effect on both human and environmental health [1]
Cellulose is a highly crystalline, water-insoluble structure, consisting of linear polymeric chains of β(1→4) linked β-D-glucopyranose units [28,29]. Concerning hemicelluloses, they are amorphous polymers, mainly arabinoxylans composed of D-xylose and L-arabinose, D-glucose, or other sugars that are embedded in the plant cell walls to form a complex network of bonds
This review focuses on the metabolism of xylose to xylitol and xylonic acid by native xylose-consuming bacteria
Summary
The human population has become an undisputable force that has a deteriorating effect on both human and environmental health [1]. In the past few years, society has been trying to embrace new measures in order to become more sustainable and to tackle the waste generation problem. The zero waste (ZW) concept has been highly embraced to stimulate sustainability regarding production and consumption as well as optimal recycling and resource recovery, while restricting mass incineration and landfilling [5]. Within this concept, the material flow is circular, which means no materials are wasted. Umbrella, where biomass-based wastes are transformed into useful bio-compounds [6] This biorefinery vision contributes to sustainability due to its inherent dependence on renewable bioresources and by recycling wastes. Worldwide concerns prompted world leaders to act [9,10]
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have