Various species of microorganisms participate in the fermentation of a wide variety of biological matrices, contribute functional substances to different fermented foods and give them nutritional, organoleptic and sensory profiles that define their identity or typicality. Spontaneous fermentations of plant matrices can be used to isolate strains of microorganisms suitable for producing products with new textures, flavors or aromas, or for improving the nutritional profile of foods in "targeted fermentations".

The current interest of the group is to investigate the genetic and functional biodiversity of microorganisms associated with raw materials and spontaneous food fermentations, in order to select and/or generate new strains suitable for microbiological innovation in baking and winemaking. We evaluate the technological capabilities of yeast strains and lactic acid bacteria of beneficial species, and generate new optimized and hybrid yeasts.

We recently isolated 433 yeast strains of 9 species from a variety of Spanish cereal grains, flour types and sourdoughs (PANLEV collection); we investigated the evolution of the fungal microbiome during fermentation as a function of flour types and dough density, and selected different yeast strains of safe species (GRAS) with innovative properties for baking (Chiva et al..., 2021); we also isolated and genetically identified 577 strains of lactic acid bacteria (PANBAL collection) (Celador-Lera et al., in preparation). We have obtained, for the first time, non-GMO hybrids between yeasts isolated from sourdoughs and yeasts of oenological origin, whose imposition and technological qualities in the elaboration of innovative breads and in the experimental production of white wines were evaluated in previous projects with companies. In addition, we genetically and functionally characterized several strains of lactic acid bacteria isolated from dextran-producing rye sourdoughs, from which we obtained mutants overproducing riboflavin (vitamin B2), successfully used to biofortify experimental breads (Llamas-Arriba et al., 2021; Hernández-Alcántara et al., 2022; Díaz-Ozaeta et al., 2023).

Our objective is to formulate simple and/or combined starter cultures using yeasts and lactic acid bacteria from our collections, and to formulate new ones based on the relative abundance of species present in the microbiome of a group of selected sourdoughs. The inocula will be used to ferment proximate plant matrices (ancestral cereal flours, pseudocereals and legumes), and the best ones will be used in targeted fermentations to develop new, sustainable and reproducible ranges of gluten-free and gluten-containing bakery products. To that end, we developed a public-private collaboration project (NutriPanHealth, 2022-2025) funded by MCIN/AEI /10.13039/501100011033 EU Next Generation EU/ PRTR; a TCUE project (CICER4FOOD, 2022-2023) and participated in the PANVITDEX proof-of-concept (2022-2024). Some international collaborations have been established through the European Action COST -CA10101 "Sourdomics" and MTA agreements for the transfer of strains.

Figure 1. Workflow diagram for food biotechnology projects.

Figure 2. Ropy phenotype of 22 strains of dextran-producing lactic acid bacteria isolated from rye sourdoughs (MRS medium with 5% sucrose).

On the other hand, our laboratory has specialized in the identification of the molecular factors and mechanisms that regulate translation initiation in eukaryotes, through mutations that alter the translational regulation of GCN4 in Saccharomyces cerevisiae. Recent work on this topic describes the roles of the initiation factor eIF1A and the ribosomal protein eL33 in translation initiation and in particular, in the correct recognition of AUG and translation fidelity (Martín-Marcos et al., 2017; 2022).