Metschnikowia pulcherrima: A valuable microbial bioresource from wine for smart agrifood

Abstract

The yeast Metschnikowia pulcherrima is a microorganism of great biotechnological interest, both for improving winemaking processes and for other applications outside the wine supply chain. Previous work by the research group has allowed the acquisition and characterization of a broad collection of about 130 strains from various environments, but particularly from grape must. Accurate bioprospecting has shown a high degree of variability in terms of enzymatic activities, relevant for modulating the aroma of wine, and for bioprotection, determined as the ability to inhibit Botrytis cinerea. M. pulcherrima is also a species known for its lipid accumulation ability, a characteristic that could make it interesting for animal feed supplementation.

The study focused on the study of a test collection of 10 strains, to evaluate the performance of rapid qualitative screening methods compared to quantitative analyses of lipid accumulation determination. Although none of the rapid protocols proved to be entirely reliable, gravimetric analysis showed that the different strains accumulated lipids between approximately 3% and 21% of cell weight. Considering a possible feed application of the best performing strain, it must be taken into account that M. pulcherrima is not included in the QPS (Qualified Presumption of Safety) list compiled by the European Food Safety Authority (EFSA). Therefore, it will be necessary to carefully assess the safety of the strain, and, thanks to the availability of the genomic sequence, the first step will be to analyze the presence of genes associated with undesirable traits, such as resistance to antifungals and the ability to produce biogenic amines.

Finally, the poor reliability of rapid tests poses an obstacle to the large-scale screening of the large collection of strains available in the VUCC-DBT (Verona University Culture Collection – Dept. of Biotechnology). In fact, the availability of rapid and reliable screening is key to enhancing microbial biodiversity for the development of innovative processes and products related to, but not limited to, the wine-viticulture supply chain.