Citation: Comitini, F.; Canonico, L.; Agarbati, A.; Ciani, M. Biocontrol and Probiotic Function of Non-Saccharomyces Yeasts: New Insights in Agri-Food Industry. Microorganisms 2023, 11, 1450. https://doi.org/10.3390/ microorganisms11061450 Academic Editor: Alex Galanis Received: 29 April 2023 Revised: 27 May 2023 Accepted: 28 May 2023 Published: 30 May 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). microorganisms Review Biocontrol and Probiotic Function of Non-Saccharomyces Yeasts: New Insights in Agri-Food Industry Francesca Comitini * , Laura Canonico, Alice Agarbati and Maurizio Ciani * Dipartimento di Scienze della Vita e dell’Ambiente (DiSVA), Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy; l.canonico@univpm.it (L.C.); a.agarbati@univpm.it (A.A.) * Correspondence: f.comitini@univpm.it (F.C.); m.ciani@univpm.it (M.C.) Abstract: Fermented food matrices, including beverages, can be defined as the result of the activity of complex microbial ecosystems where different microorganisms interact according to different biotic and abiotic factors. Certainly, in industrial production, the technological processes aim to control the fermentation to place safe foods on the market. Therefore, if food safety is the essential prerogative, consumers are increasingly oriented towards a healthy and conscious diet driving the production and consequently the applied research towards natural processes. In this regard, the aim to guarantee the safety, quality and diversity of products should be reached limiting or avoiding the addition of antimicrobials or synthetic additives using the biological approach. In this paper, the recent re-evaluation of non-Saccharomyces yeasts (NSYs) has been reviewed in terms of bio-protectant and biocontrol activity with a particular focus on their antimicrobial power using different application modalities including biopackaging, probiotic features and promoting functional aspects. In this review, the authors underline the contribution of NSYs in the food production chain and their role in the technological and fermentative features for their practical and useful use as a biocontrol agent in food preparations. Keywords: biocontrol; non-Saccharomyces yeasts; functional yeasts; probiotics 1. Introduction Agri-food systems encompass the primary production of food products, as well as food storage, aggregation, post-harvest handling, transportation, processing, distribution, marketing, disposal and consumption. Microorganisms and their metabolites can support technologies to produce more sustainable products at different stages of the food chain. Traditional industrial fermentation attributes to Saccharomyces cerevisiae the most important role as a biotechnological organism involved in worldwide fermentation products such as beers, cider, wines, sake, distilled spirits, bakery products, cheese, sausages and other fermented foods. However, in the last 20 years, the world of research, and in parallel the industrial one, has started to re-evaluate the potential positive contribution of non- Saccharomyces yeasts (NSYs). They have found a pro-technological use in traditional fermentations, where they can impart peculiar and distinctive characteristics to the product, but also in other applications such as in biomedical or fundamental biological research, environmental biotechnology, heterologous protein production, biocontrol and food and feed sectors [1]. The utility of NSYs in the food field is accelerating due to a wide number of metabolic abilities that confer aroma and structure to the final products but also due to their plasticity in assimilating different substrates. They generally show low fermentation yields and higher sensitivity to ethanol stress if compared with S. cerevisiae. On the other hand, NSYs may display a great range of fermentation metabolites and end products by providing distinctive features [2]. In any case, the positive or negative contribution that each non-Saccharomyces species gives to the product strictly depends on the matrix and fermentation context (Figure 1). Microorganisms 2023, 11, 1450. https://doi.org/10.3390/microorganisms11061450 https://www.mdpi.com/journal/microorganisms