The extensive use of synthetic fertilizers and pesticides has negative consequences in terms of soil microbial biodiversity and environmental contamination. Faced with this growing concern, a proposed alternative agricultural method is the use of microorganisms as biofertilizers. Many works have been focused on bacteria, but the limited literature on yeasts and their potential ability to safely promote plant growth is gaining particular attention in recent years. Thus, the objective of this review is to highlight the application of yeasts as biological agents in different sectors of sustainable agricultural practices through direct or indirect mechanisms of action. Direct mechanisms include the ability of yeasts to provide soluble nutrients to plants, produce organic acids and phytohormones (indole-3-acetic acid). Indirect mechanisms involve the ability for yeasts to act as biocontrol agents through their high antifungal activity and lower insecticidal and herbicidal activity, and as soil bioremediating agents. They also act as protective agents against extreme environmental factors by activating defense mechanisms. It is evident that all the aspects that yeasts offer could be useful in the creation of quality biofertilizers and biopesticides. Hence, extensive research on yeasts could be promising and potentially provide an environmentally friendly solution to the increased crop production that will be required with a growing population.

Biological ageing is an essential process for obtaining some distinctive Sherry wines, such as Fino and Manzanilla. It occurs after the fermentation of the grape must due to the appearance of a biofilm on the surface of the wine called “veil of flor”. Yeasts belonging to the Saccharomyces cerevisiae species mainly comprise such biofilm. Although other species have also been found, these have been traditionally considered spoilage. Indeed, it has even been hypothesised that they may not be able to form biofilm on their own under such conditions. In the present work, four different non-Saccharomyces yeasts isolated from barrels in the Jerez area under biological ageing have been characterised through their physiological abilities, including extracellular enzymatic and biofilm-forming capabilities. Results showed not only a surprising ethanol tolerance, above 15.5% in all cases, but also a significant degree of extracellular enzyme production, highlighting the urease and proteolytic activities found in Pichia manshurica, as well as lipolytic activity in Pichia kudriavzevii, Pichia membranifaciens and Wicherhamomyces anomalus. As a conclusion, these non-Saccharomyces could be very interesting in the oenological field, beyond improving the organoleptic characteristics as well as technological features in these wines.

Plant growth-promoting yeasts are promising bioinoculants for low-input agriculture, yet their application remains underexplored. We isolated 25 epiphytic strains from Vitis vinifera subsp. sylvestris and performed systematic in vitro biochemical profiling of plant growth promoting (PGP) traits. All produced indole-3-acetic acid (IAA); 80% synthesized under L-tryptophan-free conditions, indicating tryptophan-independent routes. ACC deaminase, siderophores, ammonia release, catalase, and biofilm were widespread, whereas nutrient solubilization (P, K, Zn), polyamines, and hydrolases (proteases, chitinases, β-1,3-glucanases, lipases, esterases) were strain-dependent, guiding evidence-based selection. Twelve representatives were evaluated in greenhouse with Nicotiana tabacum; ten increased biomass, leaf area, and root traits versus the control. The standout strains were Wickerhamomyces anomalus C(H5.1), Metschnikowia pulcherrima B(B5) and C(A11.2), Pichia kudriavzevii C(A7), and Yarrowia lipolytica B(H3.1.1), each displaying broad functional repertoires and consistent greenhouse performance. Growth promotion occurred without detectable shifts in bulk soil chemistry, supporting native epiphytic yeasts as multifunctional, soil safe bioinoculant candidates.

Botrytis bunch rot, caused by Botrytis cinerea, continues to threaten grape production and quality, reinforcing the need for biological control agents adapted to the grape environment. Grape-associated microorganisms represent promising BCAs, but extracellular protein responses associated with their interaction with B. cinerea remain poorly characterized. Here, three native grape-associated microorganisms, Aureobasidium pullulans 1107, Hanseniaspora uvarum CAMM6A and Bacillus velezensis ED163, previously shown to suppress B. cinerea through competition for space and nutrients, were investigated during co-cultivation with B. cinerea B05.10. To characterize extracellular protein responses during these interactions, extracellular proteins recovered from clarified culture supernatants were analyzed by LC–TIMS–MS/MS and evaluated using differential abundance and net interaction analyses. All three BCAs maintained viable populations in the presence of the pathogen, supporting their compatibility with the co-cultivation system. However, their extracellular proteomic responses differed markedly. A. pullulans 1107 showed a specialized profile enriched in carbohydrate-active proteins, hydrolytic enzymes and cell wall remodeling functions. H. uvarum CAMM6A displayed broad extracellular proteome expansion dominated by metabolic, stress-response and cellular maintenance proteins. In contrast, B. velezensis ED163 showed a more constrained protein-level response, reflecting a distinct extracellular protein response pattern. Together, these findings reveal BCA-specific extracellular protein signatures associated with BCA–B. cinerea interactions and provide a basis for further functional studies of microbial biocontrol in viticulture.