THE SECRETOME OF THE GREEN ALGA Scenedesmus sp

VELAZQUEZ, MARIA BELEN; BARCHIESI, JULIETA; GOMEZ-CASATI, DIEGO F.; BUSI, MARIA VICTORIA

Salta

Congreso; LV Reunión de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2019

The generation of food wastes includes from agricultural scale, passing by industrial factories and up to trade and domestic uses. The principal component of wasted forest, is lignocellulose, the most abundant natural biopolymer and cheap renewable energy and carbon resources, which mainly is composed of cellulosic and lignin materials. The use of fermentable sugars produced from these materials by enzymatic treatments would add value to these wastes. Nevertheless, no practical process has still been reported for the enzymatic hydrolysis of cellulose. The main reason for this is the high cost of the required enzyme, because free cellulase presents low specific activity, is susceptible to inactivation and difficult to recycle. Cellulase is mostly studied from microbes, more commonly from fungal sources than bacterial. However, there are fewer reports of cellulase from algae. Obtaining these hydrolytic enzymes from algae would help to reduce CO2 emissions and represents economic advantages due to algae are the organisms with the higher photosynthetic yield, and can be grown in closed containers (photobioreactors) or tanks in fields not suitable for agriculture by using waste products such as derivatives of wastewater treatment and flue gas as nutrients. At the same time, the determination of the optimal conditions for its higher photosynthetic efficiency, would help to increase the productivity in microalgae, which could be used to increase the food and/or biofuels production. The relationship between photoprotective thermal dissipation and productivity is the key for a biorefinery to manage to compete with petroleum products and materials. Recently, we have detected the presence of extracellular cellulase activity in photoheterotrophic microalgae of fresh water. This work is based on Scenedesmus quadricauda strain. It is a genus of green algae, freshwater, not mobile, which are usually grouped forming colonies of four cells. For the evaluation of the suitable conditions for cellulose secretion we grew the algae at different temperatures (range 4 to 30 °C) and acidity (pH range 3 to 7) in agar plates containing TAP, TAP-MINIMUM and B3N medium in presence and absence of water-soluble cellulose derivative carboxymethyl cellulose (CMC) with and without light (darkness). After five days the plate was revealed with congo red. The results demonstrate that cellulolytic activity can be inducible by substrates, since activity is only observed in those media supplemented with CMC. The identification and molecular characterization of these cellulases is being carried out because they constitute biotechnological targets for the treatment of effluents, CO2 capture and production of biofuels