Conservation of the Biocatalytic Activity of Whole Yeast Cells by Supported Sol – Gel Entrapment for Efficient Acyloin Condensation

Abstract

In this study, an efficient and generally applicable 2 nd generation sol -gel entrapment method was developed for immobilization of yeast cells. Cells of Lodderomyces elongisporus, Candida norvegica, Debaryomyces fabryi, Pichia carsonii strains in admixture with hollow silica microspheres support were immobilized in sol -gel matrix obtained from polycondensation of tetraethoxysilane. As biocatalysts in the selective acyloin condensation of benzaldehyde catalyzed by pyruvate decarboxylase of the yeast, the novel immobilized whole-cell preparations were compared to other states of the cells such as freshly harvested wet cell paste, lyophilized cells and sol -gel entrapped preparations without hollow silica microspheres support. Reusability and storability studies designated this novel 2 nd generation solgel method as a promising alternative for solid formulation of whole-cells bypassing expensive and difficult downstream steps while providing easy-to-handle and stable biocatalysts with long-term preservation of the biocatalytic activity.

Preparation of Hybrid Sol-Gel Materials Based on Living Cells of Microorganisms and Their Application in Nanotechnology

“…FE-SEM images of baker’s yeast encapsulated in sol–gel silica: ( e ) [ 63 ]. ( f ) Freshly harvested Lodderomyceselongisporus cells immobilized in a second generation (supported with hollow-silica microspheres) sol-gel system [ 67 ]. ( g ) Cryptococcus curvatus encapsulation in silica sol-gel.…”

“…Most often, alkoxides of the corresponding chemical elements are used as initial precursors for sol-gel reactions. In the case of silicon, tetramethoxysilane Si(OCH 3 ) 4 (TMOS) [ 45 , 69 ] and tetraethoxysilane Si(OCH 2 CH 3 ) 4 (TEOS) ( Figure 1 d) [ 27 , 34 , 65 , 67 , 70 , 71 , 72 , 73 ] are most commonly used.…”

“…Controlled evaporation of alcohol in vacuum is another way to eliminate its harmful effects [ 27 ]. Cells immobilized in silicagel are not only effective when reused [ 67 ] but also retain activity up to 90% [ 43 ], from 45 days [ 58 ] to 365 days [ 21 , 43 ].…”

“3-in-1” Hybrid Biocatalysts: Association of Yeast Cells Immobilized in a Sol–Gel Matrix for Determining Sewage Pollution

“…Combining living microbial cells with sol–gel technology allows for the creation of hybrid biomaterials or biohybrids. − Immobilizing biomaterials in organosilicate matrices offers several advantages over those of organic and inorganic polymers. Cells coated with a protective shell or embedded in an inorganic matrix become stable “living materials” − and can serve as promising biocatalysts, meeting the demands of ecological applications.…”

Characterization of Yeast Strains with Ketoreductase Activity for Bioreduction of Ketones

“…Furthermore, wild-type yeasts contain several metabolic pathways involving enzymes which can be applied to produce enantiopure compounds. Yeasts have already been applied successfully in acyloin condensation [10], bioreductions and amine production [11], as well as acylation of alcohols and amines [12]. Most yeasts harbor several ketoreductases (KREDs) with different properties.…”