Characterization of the strains of the INIA Microorganism Collection for their application in functional food:
Our research group studies the technological and health-promoting properties of the lactic acid bacteria and bifidobacteria strains of our collection using in vivo and in vitro models. Our research activity is focused in the development of functional food, with a special interest in improving health conditions in the senescence.
Some of these strains have shown immunomodulatory properties and protection of the epithelial barrier function in an animal model of experimental colitis, or are able to produce antimicrobial compounds. The application of compatible combinations of these strains could lead to additive or synergistic beneficial properties and, in some cases, we could get a double food-gut combined effect.
Another line of research studies the capacity of some bacterial strains to metabolize phytoestrogens. These polyphenols are present in vegetable foods, and could be transformed by some strains in more bioavailable compounds, with a higher antioxidant and antiestrogenic activity. These compounds are related with the prevention of age-related pathologies. We have identified the first strains of potential biotechnological interest (lactic acid bacteria and bifidobacteria) that are able to produce bioactive isoflavones, enterolignans and urolitins, from isoflavones, lignans and ellagitannins, respectively. We are currently studying other health-promoting properties, such as the production of short chain aminoacids.
We have deeply studied the bifidobacteria isolated from human milk and breastfed infant's faeces of the INIA culture Collection. We have selected some of these strains based on their technological features and probiotic potential. Some of these strains have shown good candidates for their use as adjunct probiotic cultures in the manufacture of dairy products as sheep milk cheese. This is the case of Bifidobacterium breve INIA P734, patented in 2012.
In the event of strains with interesting properties, we further study their resistance to gastrointestinal conditions in vivo in animal models, and in vitro under simulated gastric conditions and in a colonic model. This is an indispensable requisite for these strains to reach the intestine in sufficient levels and exert their health beneficial effect in the host. We also study their technological properties during the functional food manufacture and their resistance to refrigeration, freeze, lyophilization and scale-up processes.
We have also studied the production of antimicrobial compounds by the INIA culture collection strains. We have identified reuterin producing Lactobacillus reuteri strains or lactic acid bacteria that are able to produce bacteriocins, as some nisin A producing Lactococcus lactis strains. We have manufactured cheese using these strains as adjunct cultures to the commercial starter and they have been able to produce in situ reuterin or nisin A, respectively, during the cheese manufacture and ripening process. Moreover, we have detected the production of these antimicrobial compounds in intestinal environments.
Development of vectors for lactic acid bacteria and bifidobacteria
We have developed vectors for the labelling of our strains with fluorescent proteins. This has allowed us to track our strains with biotechnological interest in food, in an in vitro colon model and in the animal gastrointestinal tract.
Using similar genetic constructions, we have created biosensors for the detection of the antimicrobial peptide nisin. They contain a vector based the plasmid pNZNis that expresses fluorescence in the presence of nisin. Using this tool we have been able to detect with great sensitivity the presence of nisin in complex matrixes such as food and intestinal content.
We have also developed other expression vectors for the heterologous expression of colicin V in bacteriocin producing lactic acid bacteria.
Moreover, we have constructed food-grade vectors for the production of enzymes with biotechnological interest.
Whole genome secuencing of strains with biotechnological interest
In order to have a deeper insight into the strains that show a higher potential, these have been sequenced and subjected to a functional analysis of their genome. This is an essential aspect for their use in new and differentiated functional products. Nowadays we have six sequenced strains.