Biomass and Intra-polysaccharide Production from Starchy Waste Using Agaricus brasiliensis in a Bench-scale Bioreactor
Agaricus brasiliensis is an edible and medicinal mushroom used worldwide by its pharmacological potential. The objective of this work was to study the submerged fermentation (SmF) of A. brasiliensis for production of mycelial biomass and intracellular polysaccharides (IPS) from laboratory scale up to bench scale in a 7 L stirred-tank bioreactor considering the addition of olive oil and two carbon sources (industrial glucose and gelatinized starch from waste potato) in combination with different initial medium pH (4.5, 5.5 and 6.5) and fermentation times. Three experimental designs were performed to study the effect of the strain, olive oil, carbon source, initial pH of the medium, and time on production of biomass and IPS. SmF with GS-based (Gelatinized starch) medium was studied in the bioreactor with and without pH control compared to the medium with glucose. Response variables were as follows: biomass, reducing sugars, polysaccharides, IPS, viscosity, and broth pH. The time profiles of the cultivations were obtained. Best fermentation conditions at bench-scale were as follows: 10 g/L olive oil in a gelatinized-starch-based medium with initial pH 4.5 without pH control at 25°C, 250 rpm and 1 vvm aeration rate during 6 days of cultivation. These conditions enabled an average 33.2% increase in biomass production and 40.4% increase in IPS related to the control fermentation using glucose. The outcomes found in this work demonstrated that gelatinized starch extracted from waste potato is a suitable lowcost carbon source for this process and could be the base to design a SmF technology for A. brasiliensis cultivation at industrial scale.
Sandra Montoya*, LM Vargas-del-Rio and Oscar J Sanchez