ABSTRACT
Kinetic resolution of the enantiomers of trans -1-phenylpropene oxide and (2,3-epoxypropyl)benzene was achieved by yeasts from the genus Rhodotorula. The resolution of trans -1-phenylpropene oxide by Rhodotorula glutinis UOFS Y-0123 yielded (1R,2R)-epoxide (ee >98%, yield 30%) and (1R,2S)-diol (ee 95%, yield 40%). The highest enantio- and regioselectivity toward (2,3-epoxypropyl)benzene resided in Rhodotorula sp. UOFS Y-0448 (E = 6.16), yielding (S)-epoxide (ee 64%, yield 33%) and (R)-diol (ee 67%, yield 28%). This confirms the superiority of yeasts from the Basidiomycetes genera in the enantioselective hydrolysis of epoxides from different structural classes.
Subject(s)
Epoxide Hydrolases/metabolism , Epoxy Compounds/metabolism , Rhodotorula/classification , Rhodotorula/enzymology , Enzyme Activation , Epoxide Hydrolases/chemistry , Epoxy Compounds/chemistry , Hydrolysis , Isomerism , Kinetics , Sensitivity and Specificity , Species Specificity , Substrate SpecificityABSTRACT
Epoxides are often highly hydrophobic substrates and the presence of an organic co-solvent within an aqueous bioreactor is in such cases indicated. The effect of 40 water-miscible and -immiscible organic solvents on epoxide hydrolase activity in whole-cells of the yeast Rhodotorula sp. UOFS Y-0448 was investigated. No formal correlation between solvent biocompatibility and physicochemical properties was deductible, although the introduction of hydroxyl groups increased biocompatibility. 1-Pentanol, 2-methylcyclohexanol and 1-octanol were the most biocompatible resulting in relatively low activity losses when used at up to 20% (v/v).
Subject(s)
Epoxide Hydrolases/antagonists & inhibitors , Epoxide Hydrolases/metabolism , Organic Chemicals/pharmacology , Rhodotorula/drug effects , Rhodotorula/enzymology , Solvents/pharmacology , Water/chemistry , Biocompatible Materials/chemistry , Biocompatible Materials/pharmacology , Bioreactors/microbiology , Enzyme Activation , Materials Testing , Organic Chemicals/chemistry , Solvents/chemistry , Substrate SpecificityABSTRACT
Four strains of an ascogenous yeast were isolated from the guts of the woodlice species Armadillidium vulgare (Latreille). This yeast differed from all known yeasts by its inability to grow in culture without the presence of a metabolite produced by some common soil fungi such as Cladosporium cladosporioides, Aspergillus alliaceus, and Penicillium spp. Phylogenetic analysis based on 18S rDNA and 26S rDNA (domain D1/D2) sequences indicated that the yeast represents a new taxon in the genus Debaryomyces. The new species Debaryomyces mycophilus is thus proposed. It was, furthermore, shown that the fungal metabolite necessary for growth of D. mycophilus did not provide the yeast with carbon, nitrogen or vitamins. The active compound was partially purified and it was shown that it is a siderophore used by the yeast as a source of iron. The addition of ferrichrome or high concentrations of FeCl(3) to growth media replaced the obligate dependence on a fungal metabolite. Symbiosis among fungi, based on the availability and utilization of iron, is an aspect of mycology that has not previously been recognized. The addition of chelated iron to isolation media could lead to the discovery of many unknown yeasts and fungi.
