BIOPROSPECTING OF FUNGAL ENZYMES FOR APPLICATION IN MICROALGAL BIOMASS BIOREFINERIES

BADER A; SÁNCHEZ RIZZA, LARA; CONSOLO, VERÓNICA FABIANA; CURATTI, LEONARDO

Rosario, Santa Fé

Congreso; V Encuentro y II Workshop de la Red Argentina de Tecnología Enzimática; 2023

REDBIO, Red de Laboratorios de biotecnología para América Latina y el Caribe

Fungal enzymes for bioconversion of microalgal biomass in biofuel and application in biorefineriesBader, A.N; Sánchez Rizza, L.; Consolo, V. F.; Curatti, L.Instituto de Investigaciones en Biodiversidad y Biotecnología (INBIOTEC-CONICET) y Fundación para la Investigaciones Biológicas Aplicadas (FIBA) Vieytes 3103. CP 7600. Mar del Plata.*email aracelibdr@inbiotec-conicet.gob.arMicroalgal and/or cyanobacterial biomass is a promising feedstock for ethanol, feed/food and biomaterials. On the one hand, for the production of bioethanol, biomass saccharification is required, which can be carried out through very expensive physicochemical or enzymatic processes. Additionally, the main disadvantage presented by the production and commercialization of commodities of a single product such as bioethanol is not yet economically viable, so obtaining multiple products from a biomass biorefinery still faces various techno-economic challenges. The objective of our study was to identify fungal enzymes with hydrolytic activity for the saccharification of microalgae biomass. Native fungal isolates were studied, where the activity of the secreted enzymes was quantified using Chlamydomonas reinhardtii biomass. These tests showed as a result that Trichoderma harzianum IB-78 strain and Aspergillus niger IB-34 strain were good candidates for biomass hydrolysis. Solid state fermentation in wheat bran produced the most active enzyme preparations. The secretome of the A. niger strain was analyzed by LC-MS and sixty-five proteins were identified, most of which corresponded to predicted secreted proteins belonging to the gene ontology categories of catalytic activity and hydrolase activity of glycosylated compounds and O-glycosylated.A proof of concept for an enzyme-assisted biomass biorefinery, the defatted biomass of two most biotechnologically relevant strains for the production of commodities used in our laboratory as Chlorella sorokiniana and Scenedesmus obliquus, were completely removed after a mild pretreatment at 80 °C for 10 min, with a biomass of high load of 10% (w/v). The defatted and saccharified biomass of both strains was subsequently converted to ethanol by fermentation with Saccharomyces cerevisiae at maximum theoretical efficiency, either by separate or simultaneous saccharification and fermentation. Insoluble protein remaining after the biomass was defatted with an organic solvent and enzymatically saccharified was found to have high digestibility in an in vitro digestion test. A total of 81% of the major biomass fractions was recovered in a form probably active for the conversion of lipids and carbohydrates to biofuels and protein to feed/food.