[Ethanol into acetaldehyde bioconversion by mutant strains of Hansenula polymorpha Felcao de Morais & Dália Maia]

The influence of some factors (tris-HCl buffer, pH 8.0, concentration, use of different binding agents aeration modes, genetically determined peroxisome degradation damage) on biotransformation efficiency of 0.217 M (1%) ethanol to acetaldehyde at 30 degrees C by Hansenula polymorpha 7-4A (gcrl EAO) strain cells with glucose repression block was investigated. Optimal cultivation conditions for cells were selected. Bioconversion efficiency using 1 M tris-HCl buffer, pH 8.0, was found the highest one as compared with using the buffer in concentrations from 0.1 M to 3 M. The process efficiency when using tris(hydroxymethyl)aminomethane as binding acetaldehyde agent proved much higher than when using sodium bisulfite both at aeration by air stream and incubation on shaker. Using 146 and 179 mutants cells for bioconversion with defects in alcohol oxidase inactivation during macropexophagy stimulated efficiency increase by 5.58% and 8.10%, respectively, as compared with the use of parental 7-4A strain cells.