Immobilised derivatives of Williopsis californica, Williopsis saturnus, Pachysolen tannophilus: New biocatalysts useful in the stereoselective oxidation of 1-tetralol

Four new whole cell biocatalysts have been selected after a high throughput screening of microorganisms from public collections: Williopsis californica CBS 2158, Williopsis saturnus NCYC 2313, Pachysolen tannophilus NCYC 1597 and Coniochaeta velutina CBS 981.68, in basis to the high yield and stereoselectivity in the oxidation of 1-tetralol. These microorganisms were immobilised in different supports by entrapment techniques, being especially remarkable the results obtained with different tailor made agar matrix from Hispanagar (Spain). The selection of the immobilization conditions for each strain was performed following a statistical design based in the response surface methodology. The immobilised biocatalysts – Williopsis californica and Williopsis saturnus – immobilised in tailor-made agar (2.5%) from Pterocladia and Gracilaria (Hispanagar S.A.) carry to 100% yield in the oxidation of cyclohexanol. The immobilised biocatalysts displayed a high S-stereoselectivity (ee > 98% and 50% yield) in the oxidation of (R,S)-1-tetralol and a high yield in the oxidation of bulky substrates as 2-adamantanol (100%). The kinetic studies showed that the diffusion of reagents/products is the rate controlling step. The addition of glucose (0.5%) increases the oxidation yields.