biomass, microalgae, Synechococcus nidulans, cashew bagasse, carotenoids.

In recent years, interest in microalgae cultivation has been growing and receiving great attention, and this is due to the demands of the consumer market, which is increasingly demanding the use of ingredients from natural sources for cosmetics formulation. Brazil represents the fourth largest cosmetics market in the world, with great potential for the cultivation of microalgae species in favorable climatic conditions. Allied to this, the biotechnological concept appears, which is applied in the use of the photosynthetic capacity of the microalgae to produce biomass, which is the source for the extraction of compounds of interest. Thus, the objective of this research was to use a source of organic carbon, the Cashew Bagasse Extract (EBC), as a nutrient for the cultivation of the microalgae Synechococcus nidulans and carry out a bioprospection of the biomass obtained, combined with the environmental benefits due to the reduction of waste generated by agroindustry, contributing positively to the control and improvement of the environment, with the possibility of adding commercial value to waste in general. In this context, the present study evaluated the cell growth parameters and biomass productivity of the microalgae Synechococcus nidulans in autotrophic and mixotrophic conditions using cashew apple bagasse extract as a source of organic matter varying in concentrations of 0.5%, 1.5 % and 2.5%. The biomass composition was evaluated in terms of carbohydrates, proteins, lipids, ash and carotenoids. Cultivations were carried out in triplicate, under controlled conditions (temperature of 24 ± 1ºC, lighting 40 W, constant aeration, photoperiod of 12h light/dark). However, the analyzes showed variability for the cultures studied. Crops subjected to stress showed better biomass yields. There was a 25.9% drop in ash levels as you subjected the crop to stress and increased EBC concentration, unlike carbohydrate levels which increased by up to 28.5%  with increasing EBC compared to to control cultivation. Regarding the production of total proteins, the culture subjected to stress with the addition of EBC 2.5% stood out with 54.07 ± 3.59%. The results showed that the use of EBC in the production of bioactives by the microalgae was not able to promote the obtaining of better yields of total lipids and total carotenoids in relation to the control culture (13.22 ±0.25% and 10.02 ±4.33 mg.g-1 ). In general, these results demonstrate that the microalgae under study contain biocompounds of interest to the cosmetics industry and that these are likely to be commercially exploited.