Engineering Saccharomyces cerevisiae for targeted hydrolysis and fermentation of glucuronoxylan through CRISPR/Cas9 genome editing.

Background: The abundance of glucuronoxylan (GX) in agricultural and forestry residual side streams positions it as a promising feedstock for microbial conversion into valuable compounds. By engineering strains of the widely employed cell factory Saccharomyces cerevisiae with the ability to directly hydrolyze and ferment GX polymers, we can avoid the need for harsh chemical pretreatments and costly enzymatic hydrolysis steps prior to fermentation. However, for an economically viable bioproduction process, the engineered strains must efficiently express and secrete enzymes that act in synergy to hydrolyze the targeted polymers.

Yeasts Have Evolved Divergent Enzyme Strategies To Deconstruct and Metabolize Xylan.

Together with bacteria and filamentous fungi, yeasts actively take part in the global carbon cycle. Over 100 yeast species have been shown to grow on the major plant polysaccharide xylan, which requires an arsenal of carbohydrate active enzymes. However, which enzymatic strategies yeasts use to deconstruct xylan and what specific biological roles they play in its conversion remain unclear.

Cellulose- and xylan-degrading yeasts: Enzymes, applications and biotechnological potential.

Microbes and their carbohydrate-active enzymes are central for depolymerization of complex lignocellulosic polysaccharides in the global carbon cycle. Their unique abilities to degrade and ferment carbohydrates are also utilized in many industrial processes such as baking, brewing and production of biofuels and drugs. Effective degradation and utilization of cellulose and hemicelluloses is important for the shift towards green bioeconomy, and requires microbes equipped with proper sets of carbohydrate-active enzymes (CAZymes).

CAZyme prediction in ascomycetous yeast genomes guides discovery of novel xylanolytic species with diverse capacities for hemicellulose hydrolysis.

Background: Ascomycetous yeasts from the kingdom fungi inhabit every biome in nature. While filamentous fungi have been studied extensively regarding their enzymatic degradation of the complex polymers comprising lignocellulose, yeasts have been largely overlooked. As yeasts are key organisms used in industry, understanding their enzymatic strategies for biomass conversion is an important factor in developing new and more efficient cell factories.

Phenolic cross-links: building and de-constructing the plant cell wall.

Covering: Up to 2019Phenolic cross-links and phenolic inter-unit linkages result from the oxidative coupling of two hydroxycinnamates or two molecules of tyrosine. Free dimers of hydroxycinnamates, lignans, play important roles in plant defence. Cross-linking of bound phenolics in the plant cell wall affects cell expansion, wall strength, digestibility, degradability, and pathogen resistance.