The bioreduction of a β-tetralone to its corresponding alcohol by the yeastTrichosporon capitatumMY1890 and bacteriumRhodococcus erythropolisMA7213 in a range of ionic liquids

Abstract

The stereospecific reduction of 6-Br-b-tetralone to its corresponding alcohol (S)-6-Br-b-tetralol was carried out by the yeast Trichosporon capitatum MY1890 and by the bacterium Rhodococcus erythropolis MA7213, using a range of ionic liquids chosen for the diversity of their composition. The decrease in cell viability of both types of cell upon exposure to ionic liquids was found to be between that determined for cells residing purely in fermentation media, and cells residing in a twophase mixture of media and organic solvent (toluene). For T. capitatum MY1890 bioconversions, the water-miscible hydrophilic ionic liquid [Emim][TOS] gave a reaction profile comparable to that observed in the previously studied waterÁ ethanol (10% v/v) system, in terms of overall rate of reaction (0.2 g (prod) L (1 h (1 ) and conversion (100%). Of the hydrophobic ionic liquids evaluated, [Oc 3 MeN][BTA] gave the best conversion of 60%, but at a much reduced rate, suggesting solute mass transfer from the ionic liquid phase was rate-limiting. For bioconversions carried out with R. erythropolis MA7213 employing 20% v/v [Emim][TOS] as a co-solvent, the conversion yield doubled, and a fourfold increase in initial rate was found compared to the standard ethanol co-solvent. This was attributed to improved cell viability and reduced aggregation of the R. erythropolis MA7213 compared to T. capitatum MY1890. Overall, this study demonstrates the feasibility of using ionic liquids for whole cell biocatalysis; however, no obvious link is apparent between the physico-chemical properties of ionic liquids, their influence on cell viability, and their efficacy as media for bioconversions.

Markedly improving asymmetric oxidation of 1-(4-methoxyphenyl) ethanol with Acetobacter sp. CCTCC M209061 cells by adding deep eutectic solvent in a two-phase system

“…In this case, it was found that the substrate and product had notably inhibitory and toxic effects on the microbial cells in the aqueous monophasic system, probably resulting in the low reaction efficiency. Generally, a biphasic system has been developed in order to solve the above-mentioned problems [ 11 , 12 ], where an aqueous phase contains microbial cells and a water-immiscible organic solvent or ionic liquid phase acts as a reservoir for substrate and product. In many cases [ 13 – 16 ], use of a biphasic system especially containing more biocompatible ionic liquid was shown to be effective in lowering the inhibitory and toxic effects of substrate and product on microbial cells and thus increasing the concentration of reactant.…”

Ionic liquids in whole-cell biocatalysis: a compromise between toxicity and efficiency

“…To date, ILs have found applications in various types of whole-cell biocatalytic reactions, among which are biofuel production (Arai et al 2010;Ouellet et al 2011;Frederix et al 2016;Hashmi et al 2017;Pérez de los Ríos et al 2017), enantioselective reduction of ketones (Howarth et al 2001;Pfruender et al 2004Pfruender et al , 2006Lou et al 2006;Bräutigam et al 2007;Hussain et al 2007;Schroer et al 2007;Zhang et al 2008;Bräutigam et al 2009;Lou et al 2009a, b and c;Wang et al 2009Wang et al , 2013Dennewald et al 2011Dennewald et al , 2012Xiao et al 2012;Zhang et al 2012;Silva et al 2013;Zampieri et al 2013;Li et al 2015;Xu et al 2016bXu et al , 2017, enantioselective sulfoxidation (Gao et al 2014), enantioselective hydrolysis (Matsumoto et al 2014), enantioselective hydroxylation (Cornmell et al 2008;Wu et al 2011;Mao et al 2012Mao et al , 2013, dehydrogenation (He et al 2011), double-bond hydrogenation (Lenourry et al 2005;Castiglione et al 2017), glycosylation (Schmideder et al 2016), and nucleoside acylation (Yang et al 2014) (see Table 2).…”

“…Presumably, in the case of microorganisms, the damage to the cell membrane is one of the main reasons of IL toxicity. Thus, it was shown that [C n MIM][Cl] with long alkyl chains (n = 6, 8, 10) caused membrane damage, whereas cholinium ILs were less toxic, though their toxicity increased upon increasing (Howarth et al 2001;Pfruender et al 2004Pfruender et al , 2006Lou et al 2006;Bräutigam et al 2007;Hussain et al 2007;Schroer et al 2007;Zhang et al 2008;Bräutigam et al 2009;Lou et al 2009a, b, c;Wang et al 2009Wang et al , 2013Dennewald et al 2011Dennewald et al , 2012Xiao et al 2012;Zhang et al 2012;Silva et al 2013;Zampieri et al 2013;Li et al 2015;Xu et al 2016bXu et al , 2017 Hydrolysis of glycyrrhizin Penicillium purpurogenum, Escherichia coli, Pichia pastoris (Chen et al 2012) Enantioselective hydrolysis Rhodotorula glutinis (Matsumoto et al 2014) Enantioselective hydroxylation Escherichia coli, Penicillium raistrickii, Aspergillus ochraceus, Rhizopus nigricans (Cornmell et al 2008;Wu et al 2011;Mao et al 2012Mao et al , 2013 Enantioselective Bräutigam et al (2009) the length of the alkanoate anion. [C n MIM][Cl] also upregulated the expression of genes involved in the biosynthesis of saturated fatty acids (Jing et al 2014a, b;Hartmann et al 2015).…”

“…Biocompatible, according to some reports (20% (v/v) did not impose significant effects in 5 h); according to one report, 9% (Cornmell et al 2008) [C 14 (C 6 ) 3 P][NTf 2 ] Biocompatible (Cornmell et al 2008;Gao et al 2014) [C 14 (C 6 ) 3 P][Doc] Imposed no effect on cell growth at 2% Imposed no significant effect at 50% (v/v) (Hussain et al 2007) […”

Bioreduction of Some Common Carbonylic Compounds Mediated by Yeasts

“…3). This behaviour could be explained as a fast absorption or adsorption of the ester by the yeasts due to its low solubility in water (Hussein et al, 2007).…”