Reduced Production of Higher Alcohols by <i>Saccharomyces cerevisiae</i> in Red Wine Fermentation by Simultaneously Overexpressing <i>BAT1</i> and Deleting <i>BAT2</i>

In red wine, the contents of higher alcohols and ethyl carbamate (EC) are two significant health concerns. To reduce the production of higher alcohols by wine yeast YZ22 with low production of EC, one <i>BAT2</i> was replaced by a <i>BAT1</i> expression cassette first and then another <i>BAT2</i> was deleted to obtain the mutant SYBB3. Real-time quantitative PCR showed that the relative expression level of <i>BAT1</i> in SYBB3 improved 28 times compared with that in YZ22. The yields of isobutanol and 3-methyl-1-butanol produced by mutant SYBB3 reduced by 39.41% and 37.18% compared to those by the original strain YZ22, and the total production of higher alcohols decreased from 463.82 mg/L to 292.83 mg/L in must fermentation of Cabernet Sauvignon. Meanwhile, there were no obvious differences on fermentation characteristics of the mutant and parental strain. This research has suggested an effective strategy for decreasing production of higher alcohols in <i>Saccharomyces cerevisiae</i>

MOESM1 of Heterologous expression of Spathaspora passalidarum xylose reductase and xylitol dehydrogenase genes improved xylose fermentation ability of Aureobasidium pullulans

Additional file 1: Table S1. Primers used for genetic manipulation of A. pullulans var. melanogenum CBS 110374

MOESM2 of Heterologous expression of Spathaspora passalidarum xylose reductase and xylitol dehydrogenase genes improved xylose fermentation ability of Aureobasidium pullulans

Additional file 2: Figure S1. The sketch map for knock-in of XI gene by one-step homologous recombination-based method. Figure S2. PCR verification of the transformant with overexpressed XI gene. Figure S3. PCR verification of the transformant with overexpressed XYL1.1 (A), XYL1.2 (B), XYL2.1 (C) and XYL2.2 (D). Figure S4. PCR verification of the transformant with overexpressed XYL1.1 and XYL2.1 (A), XYL1.1 and XYL2.2 (B), XYL1.2 and XYL2.1 (C), XYL1.2 and XYL2.2 (D). Figure S5. Comparing the production of pullulan, heavy oil and melanin of the strains with single overexpressed XR gene or XDH gene with that of the parent strain

Atroposelective Synthesis of Aldehydes via Alcohol Dehydrogenase-Catalyzed Stereodivergent Desymmetrization

Axially chiral aldehydes have emerged recently as a unique class of motifs for drug design. However, few biocatalytic strategies have been reported to construct structurally diverse atropisomeric aldehydes. Herein, we describe the characterization of alcohol dehydrogenases to catalyze atroposelective desymmetrization of the biaryl dialdehydes. Investigations into the interactions between the substrate and key residues of the enzymes revealed the distinct origin of atroposelectivity. A panel of 13 atropisomeric monoaldehydes was synthesized with moderate to high enantioselectivity (up to >99% ee) and yields (up to 99%). Further derivatization allows enhancement of the diversity and application potential of the atropisomeric compounds. This study effectively expands the scope of enzymatic synthesis of atropisomeric aldehydes and provides insights into the binding modes and recognition mechanisms of such molecules

Enhanced limonene production by metabolically engineered Yarrowia lipolytica from cheap carbon sources

Limonene is a valuable monoterpene widely used in the food and pharmaceutical industries. Previously, we successfully engineered Yarrowia lipolytica to produce limonenes. In this study, we focused on improving the titers of limonenes in Y. lipolytica by optimizing the metabolic flux of the limonene biosynthetic pathway and the medium composition. First, we adopted a combinatorial gene (over)expression strategy to improve the production of limonenes, obtaining the highest titer production strains. Subsequently, the medium composition and fed-batch fermentation were optimized to improve limonene biosynthesis, and it was confirmed that waste cooking oil (WCO) is the superior substrate to produce limonenes in Y. lipolytica. Under optimal fermentation conditions, the titers of D-limonene and L-limonene were improved to 91.24 mg/L and 83.06 mg/L from WCO. These findings provide valuable insights into the engineering of Y. lipolytica for a higher-level production of limonene and its utilization in converting WCO into other industrial products