Production of Carotenoids and Astaxanthin from Haematococcus pluvialis Cultivated Under Mixotrophy Using Brewery Wastewater: Effect of Light Intensity and Cultivation Time

The cultivation of Haematococcus pluvialis is pivotal in the biotechnological production of astaxanthin, a powerful antioxidant with extensive applications in the nutraceutical, pharmaceutical, and aquaculture industries. Astaxanthin accumulation is known to be enhanced under stress conditions. Recent advancements have highlighted the efficacy of mixotrophic cultivation in enhancing both biomass production and carotenoid accumulation. The aim of this work is to evaluate the effect of mixotrophic conditions induced by BWW on biomass growth and carotenoid accumulation. To this aim, experiments carried out with different light intensities and cultivation time were specifically designed. This study displays the effective production of carotenoids by H. pluvialis using brewery wastewater (BWW) as an organic source able to sustain mixotrophic conditions. Various ratios of BWW were combined with the BG11 medium. When H. pluvialis was cultivated solely in BWW or in the control medium BG11, both the biomass and astaxanthin contents were reduced compared to the higher values obtained in their blended mixtures. In particular, the BWW-BG11 1:1 system exhibited the highest values of biomass (5.46 g L−1) and astaxanthin content (2.32%) compared to both undiluted BWW (3.34 g L−1 and 1.95%) and the control BG11 (3.65 g L−1 and 0.65%), respectively. BWW significantly boosted the growth rate and metabolic activity of H. pluvialis. This dual approach not only accelerates biomass accumulation but also enhances the synthesis of carotenoids, particularly astaxanthin. The integration of mixotrophic strategies into H. pluvialis cultivation systems presents a promising avenue for optimizing the commercial production of astaxanthin, ensuring higher yields and cost-effectiveness.