Produção de carotenoides por leveduras Rhodotorula rubra, utilizando caroço de açaí (Euterpe oleracea Mart.) como substrato para a fermentação

Abstract

Carotenoids are fat-soluble bioactive compounds present in plants, animals and in microorganisms, with wide biotechnological, pharmaceutical and food applications. Rhodotorula yeasts are able to biosynthesize carotenoids inside their cells when they are subjected to adverse environmental conditions, this biotechnological process can be industrially viable if the production cost can be minimized with low-cost by-products as sources of nutrients. Therefore, the objective of this work was the production of carotenoids using açai seed as a substrate for the fermentation of the yeast Rhodotorula rubra. The açai seeds were characterized and exhibited 3,62% of cellulose; 58,61% hemicellulose, 11,63% lignin; 14% extractive; 4,63% 1,52% protein and 1,93% ash. The liquor from acid hydrolysis with diluted sulfuric acid was characterized and provided a liquor with 45.25 g/L of sugars, consisting mainly of xylose (93%), and low concentrations of inhibitors (0.0088 g / L of furfural; 0,2382 hydroxymethylfurfural and 1,76 ± acetic acid). Regarding the cultivation of yeast with acai seed as substrate, the best conditions for the production of biomass were pH 7, 40 °C and 200 rpm, while the best conditions for carotenoid biosynthesis were pH 7, 30 °C and 200 rpm. These conditions provided 2 g of dry yeast biomass and a carotenoid concentration of 37.59 µg/g of dry biomass. Among the identified carotenoids, β-carotene (77%), cis-g-Carotene (6,9%) and torulene (4,5%) were the major carotenoids. Therefore, açaí seed showed a high potential to be used as a fermentation substrate for the yeast R. rubra to biosynthesize carotenoids as a product with high added value.