Cell wall modification of the green algae Scenedesmus quadricauda.

VELAZQUEZ, MARIA BELEN; DIEGO FABIAN GOMEZ CASATI; BARCHIESI, JULIETA; BUSI, MARIA VICTORIA

Virtual

Congreso; Reunión conjunta 2020 SAIB-SAMIGE; 2020

SAIB

Scenedesmus is one of the most commonfreshwater algae genera, it can exist as unicellular organisms but  it is also frequently found in coenobia organization which consist of fouror eight cells inside a parental mother wall. The importance of these cell wallstructure relies on the fact that the cell wall is the outer boundary of thecell that interacts directly with the external environment. Scenedesmus has a three-layerd wall with cellulose, algaenan and pectin (from inside out in theorganization).  In this work we generatedtransgenic algae overexpressing carbohydrate binding modules in the cell wall.The transgenic lines obtained are larger than wild type, theirsurface-to-volume ratio are affected, and the large mass promotes sinking. Cellwall components are altered, specifically pectic layer, which increases the unionbetween cells forming a conglomerate. We observed a greater laxity of the cellwall and an increase in the amount of pectins, fact that agree the phenotype oftransgenic plants that overexpressed starch binding domains of Arabidopsisthaliana starch synthase III. Apart from lack of an efficient harvestingtechnology, one of the major difficulties in using algae is its recalcitrantcell wall, which on the other hand is considered as an excellent foodsupplement. The presence of sugars in the cell wall following hydrolysisfacilitates bioethanol production. Our results suggest that transgenic Scenedesmus have an advantage for theproduction of biofuels in terms of better access to the inner cellulose layerand facilitate its degradation and saccharification.