Survival strategies of the microalga Oedocladium cirratum in different culture conditions for biotechnological purposes

MARSILI, SN; REARTE T. A; PITTA-ALVAREZ, S. I.; CELIS-PLÁ P.; VELEZ, C

Zagreb

Simposio; EPC7 Symposium ?Life cycles and life strategies of micro- and macroalgae?; 2019

The objective of this work is to understand the organism´s response to differentculture conditions, in order to manage these in biotechnological processes to produce valuable metabolites. The aim is to observe the conditions that elicit different survival strategies: tip grow (apical growth), rhizoids (adaptation to the soil to search for nutrients), zoospores (rapid strategy of invasion of environments in search of better conditions),accumulation of starch (energy and carbon reserve) and), carotenoid rich akinetes (survival and dispersion strategy to extreme environmental conditions). The morphological characteristics were evaluated by means of optical and transmission electron microscopy, nutritional composition and the accumulation of carotenoids induced by nitrogen deficiencyin the terrestrial habit strain O. cirratum (UTEX LB 1532). To face conditions of rapid soil desiccation and high sunlight intensities, vegetative cells can develop thick cell walls and accumulate carotenoids, differentiating into akinetes. Cultures for vegetative growth were performed in 1 L bioreactors of a standard mineralized medium (medium A, Hill,1970), with aeration and continuous light at 23 ±1 °C. This culture was then subjected to nutritional stress conditions in standard mineralized medium without N (medium A-N) source for the production of akinetes rich in carotenoids. The morphological observationsand results obtained in growth and stress conditions are presented in this work. Vegetative cells: total lipids (5.27±0.77 %DW); protein (44.6±5.1 %DW); carbohydrates (48.1±4.4 %DW); chlorophyll a and b (2.4±0.66 and 4.5±0.39 mg.g-1); and akinetes: total lipids (23.7±3.16 %DW); proteins (28.2±3.16 %DW); carbohydrates (19.3±2.25 %DW);chlorophyll a and b (1.61±0.43 and 1.49±0.48 mg.g-1); total carotenoids (8.19±0.46 mg.g-1).O. cirratum has a high potential for the production of carotenoids since it is possible to control life strategies and induce the accumulation of carotenoids by modifying the culture conditions