Molecular identification of non-conventional yeasts and the screening for α-terpineol assimilation

Abstract

The present research aimed to analyze the potential consumption of a monoterpene compound, α-terpineol, by aroma-producing Yeasts. For this purpose, 23 non-conventional yeasts were selected and identified by molecular tools. Subsequently, a screening test was performed to evaluate their tolerance to α-terpineol, by cultivating them in YM broth, at pH 5.0, for 48 h. A mixture of α-terpineol and ethyl alcohol was added to the broth in concentrations ranging from 2.5 to 10.0 μL/mL (intervals of 2.5). The yeasts that survived any of these concentrations were cultured again, but this time in mineral DP liquid culture medium to assess the consumption of α-terpineol. TLC analysis was conducted to analyze the consumption of α-terpineol. The yeasts studied were identified as Clavispora lusitaniae (n=12), Rhodotorula mucilaginosa (n=8), and Lodderomyces elongisporus (n=3). Furthermore, according to the phylogenetic tree, two of these strains (C. lusitaniae and L. elongisporus) have greater genetic proximity than the yeast R. mucilaginosa. From the 23 yeasts, 6 of them were shown to be tolerant to the concentration of 2.5 μL/mL of α-terpineol. The tolerant strains were identified as C. lusitaniae (n = 1), L. elongisporus (n = 2), and R. mucilaginosa (n = 3). However, the yeast that resisted the highest concentration, R. mucilaginosa, was only 12 hours in all concentrations. It is more likely that the defense mechanism of the yeast was not able to prevent further damage to the membrane as the time in contact with α-terpineol increased. The TLC results showed that the extracts from R. mucilaginosa (CMRP3205) and L. elongisporus (CMRP3192) could be interpreted as potentially promising results of new compounds production by the yeasts.