Screening of yeasts for the production of 2-phenylethanol (rose aroma) in organic waste-based media
In this study, we isolated 28 yeast strains from samples of plant material and fermented food and evaluated the possibility of efficient production of 2-phenylethanol (2-PE) in the organic waste-based media supplemented with l-phenylalanine (l-Phe). We used whey, a by-product from milk processing, as a base for media, and either glucose or three by-products from sugar beet processing as a fermentable carbon source. Ten newly isolated yeast strains were capable of producing over 2 g l−1 2-PE through the l-Phe biotransformation in a batch mode in standard medium. Among them, we selected eight strains producing 2-PE in a range of 1·17–3·28 g l−1 in 72 h batch cultures in shaking flasks in whey-based media. The strains were assigned to five species of Meyerozyma caribbica, Metschnikowia chrysoperlae, Meyerozyma guilliermondii, Pichia fermentans and Saccharomyces cerevisiae. While S. cerevisiae is known to be a promising producer of 2-PE, the four latter species are poorly studied on this application. Results presented here are better than other reported values for batch cultures of unmodified yeast strains. Therefore, it seems that whey and by-products from sugar beet processing might be a good feedstock for 2-PE bioproduction.Significance and Impact of the Study:
2-Phenylethanol (2-PE) is an alcohol with a pleasant rosy scent, which is commonly used in the food, fragrance and cosmetic industries as an aroma compound and preservative. Promising sources of 2-PE are yeasts, but still the biotechnological route has not been economically competitive to chemical synthesis. Thus, the first challenging goal to develop biotechnological production of 2-PE is the identification of highly productive yeasts and cheap feedstock. This study demonstrates for the first time the promising production of 2-PE by selected yeasts in organic waste-based media. This could pave the way for development of a cheaper method of 2-PE bioproduction.