Edible Fungal Production using Acetic Acid as Carbon and Energy Source

Abstract: Volatile fatty acids (VFAs) have become attractive and gained high research interest due to its significance for the chemical industry and economical advantage. These acids can be produced by utilizing organic waste such as food waste as substrate through anaerobic digestion. Anaerobic digestion is an environmental process that occurs naturally and produces biogas as the main product. VFAs are intermediate products formed during anaerobic digestion where acetic acid, a type of VFA, is the primary product. The main objective of this study was to utilize acetic acid as carbon and energy source for production of edible fungi, Rhizopus ologisporus, Mucor indicus and Volvariella volvacea. The first step was to evaluate if acetic acid could be used as carbon and energy source for edible fungi production. The results showed, that acetic acid is suitable as carbon and energy source for fungal biomass production. The second step was to optimize growth in liquid media. The cultivations were carried out by using five different conditions, where the liquid media contained different combinations of acetic acid, yeast extract and minerals as well as comparing orbital and linear oscillations. Fungal cultivation was possible regardless of the medium composition and type of water shaking baths. However, a linear water shaking bath with a combination of acetic acid yeast extract and/or minerals seems to be the best. Finally, as step three, acetic acid concentrations, 0.2 g/l and 2.0 g/l were used under similar conditions as in step two to see whether a higher concentration of acetic acid would be beneficial. Although the cultivation containing 2.0 g/l gave a higher value of dry weight, the value of yield is questionable. Further studies are needed to confirm if a higher concentration is beneficial or if it might act as an inhibitor for fungal cultivation.