Sugarcane Bagasse Hydrolysate as Organic Carbon Substrate for Mixotrophic Cultivation of Nannochloropsis sp. BR2

In the present study, the mixotrophic growth of the microalga Nannochloropsis sp. BR2 in sugarcane bagasse was analyzed and compared with its photoautotrophic cultivation. Nannochloropsis cultures cultivated mixotrophically in sugarcane bagasse showed significantly higher biomass productivity, fatty acid methyl ester (FAME) and protein contents of 63.28 mg L−1 d−1, 170.51 mg g−1 and 35.2% of dry weight, respectively, compared to the photoautotrophic cultivations with biomass productivity, FAME and protein contents of 51 mg L−1 d−1, 139.21 mg g−1 and 31.6% of dry weight. Whereas, total carotenoid during photoautotrophic cultivation was 5.833 mg g−1 and decreased to 4.542 mg g−1 in mixotrophic cultures. This can be explained by the additional carbon source in the form of sugars that are metabolized to the fatty acid building block acetyl-CoA, while photosynthetic pigments were less needed. Findings of this study demonstrate that acid-pretreated hydrolysate of lignocellulosic waste from sugarcane bagasse can be developed into a potential feedstock for efficient microalgal cultivation.