ISOLATION AND CHARACTERIZATION OF MUTANTS RESISTANT TO AMINO-ACID-ANALOGS OBTAINED FROM SACCHAROMYCES-CEREVISIAE STRAINS

Mutants resistant to the amino acid analogues DL-thiaisoleucine, DL-4- azaleucine, 5,5,5-trifluoro-DL-leucine and L-O-methylthreonine, were i solated from Saccharomyces cerevisiae wine yeast strains. The fermenta tive production of secondary metabolites by the mutants was tested in grape must. Higher alcohols, acetaldehyde and acetic acid concentratio n varied depending on strain and analogue. Most of the mutants produce d increased amounts of amyl alcohol. A remarkable variability in the l evel of n-propanol, isobutanol, acetaldehyde and acetic acid was obser ved. In practical application, the use of mutants resistant to amino a cid analogues can improve the quality of wines by reducing or increasi ng the presence of some secondary compounds.