Growth of fungi and yeasts in food production waste streams: a bioremediation feasibility study

Food production produces large amounts of nutrient-rich waste streams which are disposed of - a wasted opportunity given nutrients such as phosphorus and nitrogen are in short supply. A more circular approach would be to reuse these waste streams. Fungi and yeasts are possible candidates as they require lots of organic carbon (which is especially high in food production waste streams) for growth, producing value-added biomass. Here, we determined the growth of seven fungi and three yeasts in five different food production waste streams. Initial tests were done to find the most appropriate waste stream for growth. All species were then cultured in the waste stream best suited for growth. Oxygen uptake was measured to gauge metabolic activity and as a proxy for growth rate. Pelletization’s effect on metabolic rates was tested on the most pellet-forming species, by adding agar to inhibit pellet formation. The most promising waste stream for yeast/fungal growth was cheese whey (Whey). Pellet inhibition (i.e., filamentous growth) resulted in increased metabolism in the confectionary bakery waste stream but decreased metabolism in Whey. The best growing species, Geotrichum candidum , has potential commercial value as a producer of enzymes, biochemicals and lipids and could provide added value while improving the circularity of water and nutrients in food production.