The enzymatic hydrolysis of plant cell wall material is a formidable task due to its complexity. Enzyme cocktails containing multiple classes of polysaccharide-degrading enzymes are used in several existing cellulosic ethanol plants to hydrolyze plant biomass into fermentable sugars. These enzymes are classified into families in the carbohydrate active enzyme (CAZy) database, and they include glycoside hydrolases (GHs), pectic lyases (PLs), carbohydrate esterases (CEs), and others. Due to several experimental limitations, only a small fraction of the enzymes included in CAZy have a function assigned by biochemical analysis.
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Lignin, a complex polyphenolic constituent of plant secondary cell walls, is one of the most abundant biopolymers on the planet and is an immensely important global carbon sink. The chemical recalcitrance of lignin, however, poses a major challenge for industrial biomass processing, most notably in pulp and paper production and in the emerging cellulosic biofuels industry.
Valorization of lignin from biomass is challenging and research efforts have lagged behind the upgrading of sugar streams. Yet lignin comprises a substantial portion of lignocellulosic biomass (15-30% by weight), is the most energy dense fraction, and is a rich source of aromatic compounds.
A valuable ‘new’ compound is available from lignin ‘waste’ streams. Lignin, a complex phenylpropanoid polymer in the plant cell wall, is synthesized via oxidative radical coupling reactions from three prototypical monolignols.
Soil microbial communities are an important component of ecosystems because of their key roles in nutrient cycling, influence on plant community composition, regulation of plant productivity, and decomposition of organic matter.
The recalcitrance of plant cell walls to biological degradation, deconstruction, or conversion is the most critical challenge in developing successful bioprocessing technologies for lignocellulose conversion to renewable fuels and chemicals.
By providing mechanical strength and enabling reception and transmission of developmental and environmental cues, the plant cell wall serves as a critical interface between the protoplast and the surrounding environment.
Lignocellulose-derived hydrolysates contain several different inhibitors (collectively called lignotoxins or LTs) that arise during pre-treatment of biomass. Determining the mechanisms by which yeast or bacteria are adversely affected by LTs is a key step toward improving the efficiency of fermentation and bioconversion.
A major barrier to efficient conversion of lignocellulosic materials to biofuels is sensitivity of microbes to inhibitory compounds formed during pretreatment. of inhibitors that are typically not metabolized by microbes commonly used as biocatalysts.
The prospect of converting large tracts of the Midwest’s marginal farming land to perennial biofuel crops carries with it some key unknowns, including how such a change could affect the balance of water between rainfall inputs, evaporation losses, and movement of soil water to the groundwater. In humid climates such as the U.S.
American crude oil imports have almost tripled since the early 1970s and now account for about half of the American petroleum supply, a dependence that is fueling climate change. Regulations intended to mitigate climate change, however, seek an 80% reduction in US greenhouse gas (GHG) emissions by 2050 in order to stabilize global GHG concentrations at low to medium levels.
Nitrous oxide (N2O) is a potent greenhouse gas and a substantial proportion of the total carbon footprint associated with feedstock production, and as bioenergy cropping systems continue to be considered, their greenhouse gas emissions will be a key component of sustainability evaluation.
Microbial communities that have symbiotic relationships with biomass insects are now recognized to be a relevant source of microbes with diverse metabolic and biosynthetic capabilities that could be used in improving the enzymatic deconstruction of biomass materials for biofuel production. Recently, a highly cellulolytic and hemicellulolytic Actinomycete, Streptomyces sp.
A recent breakthrough in lignocellulosic biomass deconstruction at Great Lakes Bioenergy Research Center utilizes γ-valerolactone (GVL), a renewable solvent that can be derived from the biomass itself. In a recent publication researchers at GLBRC designed a process for large-scale production of ethanol from lignocellulosic biomass that employs GVL for biomass deconstruction.
Non-productive binding of enzymes to lignin is thought to impede the saccharification efficiency of pretreated lignocellulosic biomass to fermentable sugars.
Bio-based societies could become a reality when biomass-derived renewable substitutes are found for the vast array of products currently derived from the processing of crude petroleum and other fossil sources. The biorefineries in these societies would integrate biomass conversion processes and equipment to produce fuels, power, and chemicals from biomass.
Scientists today demonstrated the potential for softwoods to process more easily into pulp and paper if engineered to incorporate a key feature of hardwoods. The finding, published in this week’s Proceedings of the National Academy of Sciences, could improve the economics of the pulp, paper and biofuels industries and reduce those industries’ environmental impact.
Lignocellulosic hydrolysates contain a number of compounds that are toxic to microbes and limit conversion of sugars to biofuels. Knowledge of the types of inhibitors formed during biomass pretreatment and/or hydrolysis and their biological targets is useful for engineering biocatalyst tolerance.
Plant seed oils offer many advantages over synthetic or mineral oils, including biodegradability, low toxicity, and exceptional lubricity.
Several types of grasses belonging to the Poaceae family can be grown as bioenergy crops in the Midwest regions of the U.S. due to its climate, soil fertility, and water availability.