title: Laboratory Prototype of Bioreactor for Oxidation of Toxic D-Lactate Using Yeast Cells Overproducing D-Lactate Cytochrome c Oxidoreductase.
abstract: D-lactate is a natural component of many fermented foods like yogurts, sour milk, cheeses, and pickles vegetable products. D-lactate in high concentrations is toxic for children and people with short bowel syndrome and provokes encephalopathy. These facts convincingly demonstrate a need for effective tools for the D-lactate removal from some food products. The main idea of investigation is focused on application of recombinant thermotolerant methylotrophic yeast Hansenula polymorpha "tr6," overproducing D-lactate: cytochrome c oxidoreductase (EC 1.1.2.4, D-lactate cytochrome c oxidoreductase, D-lactate dehydrogenase (cytochrome), DLDH). In addition to 6-fold overexpression of DLDH under a strong constitutive promoter (prAOX), the strain of H. polymorpha "tr6" (gcr1 catX/Δcyb2, prAOX_DLDH) is characterized by impairment in glucose repression of AOX promoter, devoid of catalase and L-lactate-cytochrome c oxidoreductase activities. Overexpression of DLDH coupling with the deletion of L-lactate-cytochrome c oxidoreductase activity opens possibility for usage of the strain as a base for construction of bioreactor for removing D-lactate from fermented products due to oxidation to nontoxic pyruvate. A laboratory prototype of column-type bioreactor for removing a toxic D-lactate from model solution based on permeabilized cells of the H. polymorpha "tr6" and alginate gel was constructed and efficiency of this process was tested.
authors.affiliation: Department of Analytical Biotechnology, Institute of Cell Biology, Drahomanov Street 14/16, Lviv 79005, Ukraine.
authors.forename: Maria
authors.initials: M
authors.lastname: Karkovska
authors.affiliation: Department of Analytical Biotechnology, Institute of Cell Biology, Drahomanov Street 14/16, Lviv 79005, Ukraine.
authors.forename: Oleh
authors.identifier: 0000-0002-9967-3445
authors.initials: O
authors.lastname: Smutok
authors.affiliation: Department of Analytical Biotechnology, Institute of Cell Biology, Drahomanov Street 14/16, Lviv 79005, Ukraine.
authors.forename: Mykhailo
authors.identifier: 0000-0001-8861-4477
authors.initials: M
authors.lastname: Gonchar
mesh_terms: D019149:Bioreactors; D001927:Brain Diseases / Q000139:chemically induced / Q000473:pathology; D005285:Fermentation; D005517:Foodborne Diseases / Q000201:enzymology / Q000235:genetics; D005947:Glucose / Q000737:chemistry / Q000378:metabolism; D045022:Lactate Dehydrogenases / Q000235:genetics* / Q000378:metabolism; D019344:Lactic Acid / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D010084:Oxidation-Reduction; D010843:Pichia / Q000201:enzymology* / Q000235:genetics
chemical_list: D019344:Lactic Acid; D045022:Lactate Dehydrogenases; C081234:D-lactate dehydrogenase (cytochrome); D005947:Glucose