evolution wiggle expression after effects

As the production of chemicals from renewable resources constantly faces the challenges of competition with petrochemical industry, production cost is a critical issue. Industrial biotechnology nowadays provides processes for production of many organic compounds from biomass as carbon source, but development of new processes broadening the spectrum of marketable products is needed to offer new sustainable solutions for provision of fuels, materials and energy. Moreover, our work suggests potential genetic background of the tolerance to the SSL stream pointing out potential gene targets for improving the tolerance to inhibitory industrial feedstocks. The combined metabolic engineering and adaptive evolution approach provided a robust SSL-tolerant industrial strain that converts fermentable carbon content of the SSL feedstock into malic and succinic acids at low pH.in production yields reaching 0.1 mol and 0.065 mol per mol of total consumed carbon sources. The production strain produced 0.2 mol and 0.12 mol of malic acid and succinic acid, respectively, per mol of xylose present in the SSL. The developed strains were further engineered for production of dicarboxylic acids (succinic and malic acid) via overexpression of the reductive branch of the tricarboxylic acid cycle (TCA). In particular, four top-candidate genes ( SNG1, FIT3, FZF1 and CBP3) were identified along with other gene candidates with predicted important roles, based on the type and distribution of the mutations across different strains and especially the best performing ones. Putative genetic determinants of the increased tolerance to the SSL were revealed by whole genome sequencing of the evolved strains.

Selected evolved strains utilized all carbon sources in the SSL at pH 3.5 and grew with µ max between 0.05 and 0.1 1/h depending on a nitrogen source supplement.

The engineered strain grew in synthetic medium with xylose as sole carbon source with maximum specific growth rate (µ max) of 0.28 1/h. The industrial strain Ethanol Red of the yeast Saccharomyces cerevisiae was engineered for efficient utilization of xylose in a Eucalyptus globulus lignosulfonate stream at low pH using CRISPR/Cas genome editing and adaptive laboratory evolution.

The aim of the present work was to develop a robust yeast strain able to convert xylose in SSL to carboxylic acids. SSLs are typically very inhibitory to microorganisms, which presents a challenge for a biotechnological process.

If they could be converted into value-added chemicals, overall economic profitability of the process would increase. The pentoses are currently underutilized. During the pulping process, spent sulfite liquor (SSL) is generated, which in addition to lignosulfonates contains hemicellulose-derived sugars-in case of hardwoods primarily the pentose sugar xylose. Lignosulfonates are significant wood chemicals with a $700 million market, produced by sulfite pulping of wood.

Evolution wiggle expression after effects