Abstract

Occupational oenologists have long used specific genera of yeast for alcoholic fermentation of wine; thus, the characterization of yeasts is of great importance to oenologists. In this study, commercial wine yeast (CY) with the GV1 remark and wild yeasts isolated from honey, banana fruit were characterized using standard microbiological methods. The local BLAST of the Analytical Profile Index (API) kit confirmed that the isolates (B⁷, B¹⁰, H⁷, H⁴ and CY) had 99.90% relatedness to Saccharomyces cerevisiae, Candida tropicalis, Saccharomyces cerevisiae, Candida hellenica and Candida kefyr, respectively; while molecular characterization revealed that isolates accession number MK752669, EF190223, EF198007, KF268353 and EF192229 had 93.10%, 95.00%,  94.80%, 77.60% and 92.10% relatedness to Candida tropicalis strain Pe 1, Candida tropicalis strain WC65-1, Candida tropicalis strain WC57, Clavispora lusitaniae strain WM03, and Candida tropicalis strain zhuan4, respectively. The polymorphism of the length of the restriction fragments revealed the disparity between the yeasts by indicating their molecular weight, which ranges from 400 – 600 basepairs (bp) on the molecular ladder. Wild yeasts possess Alcohol O-acetyltransferase (ATF) 1 gene, Pyruvate decarboxylase 1 (PDC 1) gene, Branched-chain amino acid transaminase (BAT) 1 gene, Thiamine pyrophosphate-dependent 2-oxo-acid decarboxylase (ARO) 10 gene, and Alcohol dehydrogenase (ADH) 1 and 2 genes in their chromosomal DNA, except isolate B10 that lack the PDC1 and ARO 10 genes. This study revealed that some locally sourced yeast isolates possess essential functional genes needed for quality wine production such as the imported commercial wine yeast.