![Sample our Environment & Agriculture journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5934/TOC-Subject-Sample-2021-Environment-Agriculture.jpg"})
Abstract
5,5,5-trifluoro-DL-leucine (TFL)-resistant bottom-fermenting yeast mutants were isolated and found to overproduce both isoamyl alcohol and isoamyl acetate. The TFL-resistant strains were found to harbor dominant mutations in either the S. cerevisiae (SC)-type or S. bayanus (SB)-type alleles of LEU4 encoding α-isopropylmalate synthase (α-IPM synthase). All TFL-resistant mutants were isolated as heterozygotes. When a single wild-type allele in the parent strain was replaced with a mutant LEU4 allele, overproduction of isoamyl alcohol and TFL resistance was observed, indicating that a single dominant mutation was responsible for both phenotypes. In addition, feedback inhibition of α-isopropylmalate synthase (α-IPM synthase) by L-leucine was found to be weaker in the mutant than in the parent. On a pilot-scale brewing experiment, the original mutants with the dominant LEU4 allele produced beer containing more isoamyl alcohol and isoamyl acetate than the parent strain.