Potential of Chlorella fusca LEB 111 cultivated with thermoelectric fly ashes, carbon dioxide and reduced supply of nitrogen to produce macromolecules

Abstract

Fly ashes present several minerals that along with carbon dioxide (CO₂) represent a promising nutrient source and an alternative to reduce environmental problems. Thus, the objective of this study was to investigate if CO₂, thermoelectric fly ashes and reduction in nitrogen supply alters the production of macromolecules in Chlorella fusca LEB 111. For this purpose, 1.5 or 0.75 g L^-1 of NaNO₃, injection of 10% (v v^-1) of CO₂ as well as 0, 40 and 120 ppm of fly ashes were studied. The protein content was not impaired in cultivations with 0.75 g L^-1 of NaNO₃ since nitrogen was not fully consumed. Nevertheless, this cultivation strategy increased carbohydrate content by up to 25%, which could be fermented to produce bioethanol. Therefore, Chlorella fusca presented not only potential for CO₂ biofixation and assimilation of nutrients from fly ashes but also for enhancement of carbohydrates accumulation when the nitrogen supply was reduced.

Keywords: Bioethanol; CO(2) biofixation; Carbohydrates; Carbon dioxide; Nutrients.