The main organism groups used and studied in the microbiology/biotechnology unit at food science are yeasts, lactic acid bacteria and bifidobacteria, all highly relevant in food science and biotechnology. The overall focus of the research unit is to improve the nutritional value of fermented foods, produce relevant specific food components, study and develop nutritional probiotics and to use microorganisms as models for nutritional questions. We use several species within each organism group; with respect to yeast, not only baker’s yeast (Saccharomyces cerevisiae) but also wild-type yeasts e.g. Pichia kudriavzevii isolated from traditional African fermented foods and beverages. The bifidobacteria strains used are either collection strains from our collaborators at Bologna University or isolated from animals in Sweden.
We use controlled cultivation in bioreactors as well as traditional fermentation techniques in combination with modern biotechnology to improve nutritional value and other properties of the food. We also develop strains to optimize microbial production of selected enzymes and vitamins. For this, we use metabolic and genetic engineering as well as classical mutagenesis to direct metabolism towards over-production.
At present, we are working with microbial production of folates (folic acid vitamin B9) and phytases in yeasts and bifidobacteria as well as lipid production in oil-accumulating yeasts. The Pichia yeast isolated from Tanzanian togwa was found to express exceptionally high levels of mineral-releasing phytase, and to secret the phytase to the surrounding medium. Selected species of yeast and bifidobacteria are also studied as candidate trophic probiotics, for in vivo production of folates and phytase, expected to improve the folate and mineral absorption in the intestine. Yeasts are also used as model systems for nutritional questions. One example is the study of factors that influence composition and content of specific folate forms in an organism. There is also ongoing research aiming at sustainable production of baker’s yeast biomass and bioethanol. Finally, we run a project aiming at sustainable production of bio-diesel from triacylglycerols produced by oil-accumulating yeasts from wood waste substrates.