SUSTAINABLE BIOFLOCCULATION STRATEGY FOR MICROALGAE BIOMASS HARVESTING USING EDIBLE FUNGI

MIÑO, ML; ZAPATA, PD; KOLMAN, MA

Chapadmalal

Congreso; XVIII Congreso de la Sociedad Argentina de Microbiologia General; 2023

SAMIGE

The utilization of microalgae in various industries has sparked interest due to their fastgrowth, high lipid content, and photosynthetic efficiency. However, the economic viability ofmicroalgae production remains a challenge, with efficient harvesting methods identified asa key area for improvement. Traditional methods can be costly and energy-intensive,prompting the exploration of environmentally friendly alternatives like bioflocculation.Bioflocculation involves the use of biological agents to aggregate microalgae, simplifyingthe harvesting process. This study investigates the potential of two edible fungi of Misionesprovince for bioflocculation of microalgae.The fungi strains used in this study were Pleurotus pulmonarius LBM 105 and Lentinussajor cajú LBM 266 from the InBioMis culture collection. Mycelium activation was carriedout in 100 mm petri dishes containing Sabouraud Agar medium, followed by a 5-dayincubation at 28°C in darkness. Subsequently, mycelium was disintegrated in sterile water,homogenized, and diluted to achieve an OD600=0.1, forming a pre-inoculum of Lentinus andPleurotus. This pre-inoculum was introduced into flasks containing Malt Extract anddextrose, and incubated for 7 days at 28°C with agitation to obtain fungal pellets.Simultaneously, four microalgae strains from InBioMis culture collection were grown in aphotobioreactor until OD750=0.5. Flocculation was achieved followed by the addition of 10gof fungal pellets to 100mL of microalgae culture. The percentage of microalgae flocculatedby the fungi was assessed by measuring OD750 and chlorophyll content. Morphologicalcharacterization of fungal pellets before and after flocculation was performed.Morphologically, Lentinus sp. displayed compact pellets with minimal mycelialprojections, while Pleurotus sp. pellets presented numerous surface projections. In thebioflocculation assay, using Lentinus sp. pellets for 24-hour showed 71% and 66% valuesfor CMI 015 and CMI 016 respectively. When Pleurotus sp. pellets were used, 99.5%flocculation was achieved for all the microalgae isolates. Microscopic observation of theLentinus-microalgae pellets showed superficial microalgal layers, while Pleurotus pelletsexhibited deeper microalgal penetration, correlating with a high percentage of flocculation.In conclusion the bioflocculation of microalgae using Lentinus sp. and Pleurotus sp.mycelial pellets proved to be an effective approach and a promising alternative forharvesting microalgae biomass for diverse applications.