scholarly journals Engineering Saccharomyces cerevisiae for co-utilization of d-galacturonic acid and d-glucose from citrus peel waste

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Ryan J. Protzko ◽  
Luke N. Latimer ◽  
Ze Martinho ◽  
Elise de Reus ◽  
Tanja Seibert ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Galacturonic Acid ◽  
Citrus Peel

scholarly journals Identification of the Aldo-Keto Reductase Responsible for d-galacturonic Acid Conversion to l-galactonate in Saccharomyces cerevisiae

2021 ◽  
Vol 7 (11) ◽  
pp. 914
Author(s):  
Dorthe Rippert ◽  
Federica Linguardo ◽  
Andreea Perpelea ◽  
Mathias Klein ◽  
Elke Nevoigt
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Galacturonic Acid ◽  
Homology Search ◽  
Cell Factory ◽  
Citrus Peel ◽  
Beet Pulp ◽  
By Products ◽  
Sequence Similarities

d-galacturonic acid (d-GalUA) is the main constituent of pectin, a complex polysaccharide abundant in several agro-industrial by-products such as sugar beet pulp or citrus peel. During several attempts to valorise d-GalUA by engineering the popular cell factory Saccharomyces cerevisiae, it became obvious that d-GalUA is, to a certain degree, converted to l-galactonate (l-GalA) by an endogenous enzymatic activity. The goal of the current work was to clarify the identity of the responsible enzyme(s). A protein homology search identified three NADPH-dependent unspecific aldo-keto reductases in baker’s yeast (encoded by GCY1, YPR1 and GRE3) that show sequence similarities to known d-GalUA reductases from filamentous fungi. Characterization of the respective deletion mutants and an in vitro enzyme assay with a Gcy1 overproducing strain verified that Gcy1 is mainly responsible for the detectable reduction of d-GalUA to l-GalA.

scholarly journals Galacturonic Acid Inhibits the Growth of Saccharomyces cerevisiae on Galactose, Xylose, and Arabinose

2012 ◽  
Vol 78 (15) ◽  
pp. 5052-5059 ◽  
Author(s):  
Eline H. Huisjes ◽  
Erik de Hulster ◽  
Jan C. van Dam ◽  
Jack T. Pronk ◽  
Antonius J. A. van Maris
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Galacturonic Acid ◽  
Competitive Inhibition ◽  
Energy Requirement ◽  
Major Constituent ◽  
Yeast Fermentation ◽  
Substrate Uptake ◽  
Citrus Peel ◽  
Content Type ◽  
The Impact

ABSTRACTThe efficient fermentation of mixed substrates is essential for the microbial conversion of second-generation feedstocks, including pectin-rich waste streams such as citrus peel and sugar beet pulp. Galacturonic acid is a major constituent of hydrolysates of these pectin-rich materials. The yeastSaccharomyces cerevisiae, the main producer of bioethanol, cannot use this sugar acid. The impact of galacturonic acid on alcoholic fermentation byS. cerevisiaewas investigated with anaerobic batch cultures grown on mixtures of glucose and galactose at various galacturonic acid concentrations and on a mixture of glucose, xylose, and arabinose. In cultures grown at pH 5.0, which is well above the pKavalue of galacturonic acid (3.51), the addition of 10 g · liter−1galacturonic acid did not affect galactose fermentation kinetics and growth. In cultures grown at pH 3.5, the addition of 10 g · liter−1galacturonic acid did not significantly affect glucose consumption. However, at this lower pH, galacturonic acid completely inhibited growth on galactose and reduced galactose consumption rates by 87%. Additionally, it was shown that galacturonic acid strongly inhibits the fermentation of xylose and arabinose by the engineered pentose-fermentingS. cerevisiaestrain IMS0010. The data indicate that inhibition occurs when nondissociated galacturonic acid is present extracellularly and corroborate the hypothesis that a combination of a decreased substrate uptake rate due to competitive inhibition on Gal2p, an increased energy requirement to maintain cellular homeostasis, and/or an accumulation of galacturonic acid 1-phosphate contributes to the inhibition. The role of galacturonic acid as an inhibitor of sugar fermentation should be considered in the design of yeast fermentation processes based on pectin-rich feedstocks.

scholarly journals The introduction of the fungal d-galacturonate pathway enables the consumption of d-galacturonic acid by Saccharomyces cerevisiae

2016 ◽  
Vol 15 (1) ◽  
Author(s):  
Alessandra Biz ◽  
Maura Harumi Sugai-Guérios ◽  
Joosu Kuivanen ◽  
Hannu Maaheimo ◽  
Nadia Krieger ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Galacturonic Acid

scholarly journals Engineering cofactor supply and NADH-dependent d-galacturonic acid reductases for redox-balanced production of l-galactonate in Saccharomyces cerevisiae

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Simon Harth ◽  
Jacqueline Wagner ◽  
Tamina Sens ◽  
Jun-yong Choe ◽  
J. Philipp Benz ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Galacturonic Acid ◽  
Major Constituent ◽  
Sugar Alcohol ◽  
Catabolic Pathway ◽  
Efficient Utilization ◽  
Yeast Strains ◽  
Potential Applications ◽  
Agricultural Byproduct ◽  
Sorbitol Metabolism

Abstract d-Galacturonic acid (GalA) is the major constituent of pectin-rich biomass, an abundant and underutilized agricultural byproduct. By one reductive step catalyzed by GalA reductases, GalA is converted to the polyhydroxy acid l-galactonate (GalOA), the first intermediate of the fungal GalA catabolic pathway, which also has interesting properties for potential applications as an additive to nutrients and cosmetics. Previous attempts to establish the production of GalOA or the full GalA catabolic pathway in Saccharomyces cerevisiae proved challenging, presumably due to the inefficient supply of NADPH, the preferred cofactor of GalA reductases. Here, we tested this hypothesis by coupling the reduction of GalA to the oxidation of the sugar alcohol sorbitol that has a higher reduction state compared to glucose and thereby yields the necessary redox cofactors. By choosing a suitable sorbitol dehydrogenase, we designed yeast strains in which the sorbitol metabolism yields a “surplus” of either NADPH or NADH. By biotransformation experiments in controlled bioreactors, we demonstrate a nearly complete conversion of consumed GalA into GalOA and a highly efficient utilization of the co-substrate sorbitol in providing NADPH. Furthermore, we performed structure-guided mutagenesis of GalA reductases to change their cofactor preference from NADPH towards NADH and demonstrated their functionality by the production of GalOA in combination with the NADH-yielding sorbitol metabolism. Moreover, the engineered enzymes enabled a doubling of GalOA yields when glucose was used as a co-substrate. This significantly expands the possibilities for metabolic engineering of GalOA production and valorization of pectin-rich biomass in general.

Enhancing bioproduction and thermotolerance in Saccharomyces cerevisiae via cell immobilization on biochar: Application in a citrus peel waste biorefinery

2020 ◽  
Vol 155 ◽  
pp. 53-64 ◽  
Author(s):  
Maria Kyriakou ◽  
Maria Patsalou ◽  
Nikolas Xiaris ◽  
Athanasios Tsevis ◽  
Loukas Koutsokeras ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Immobilization ◽  
Citrus Peel
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