Supercritical Fluid Extraction of Fucoxanthin from the Diatom Phaeodactylum tricornutum and Biogas Production through Anaerobic Digestion

Phaeodactylum tricornutum is the marine diatom best known for high-value compounds that are useful in aquaculture and food area. In this study, fucoxanthin was first extracted from the diatom using supercritical fluid extraction (SFE) and then using the extracted diatom-like substrate to produce bioenergy through anaerobic digestion (AD) processes. Factors such as temperature (30 °C and 50 °C), pressure (20, 30, and 40 MPa), and ethanol (co-solvent concentration from 10% to 50% v/v) were optimized for improving the yield, purity, and recovery of fucoxanthin extracted using SFE. The highest yield (24.41% w/w) was obtained at 30 MPa, 30 °C, and 30% ethanol but the highest fucoxanthin purity and recovery (85.03mg/g extract and 66.60% w/w, respectively) were obtained at 30 MPa, 30 °C, and 40%ethanol. Furthermore, ethanol as a factor had the most significant effect on the overall process of SFE. Subsequently, P.tricornutum biomass and SFE-extracted diatom were used as substrates for biogas production through AD. The effect of fucoxanthin was studied on the yield of AD, which resulted in 77.15 ± 3.85 LSTP CH₄/kg volatile solids (VS) and 56.66 ± 1.90 LSTP CH₄/kg VS for the whole diatom and the extracted P.tricornutum, respectively. Therefore, P.tricornutuman can be considered a potential source of fucoxanthin and methane and both productions will contribute to the sustainability of the algae-biorefinery processes.     

氮、磷富营养及海带对赤潮三角褐指藻生长的影响

三角褐指藻是极具危害的赤潮藻之一。本文研究了不同氮磷营养浓度对三角褐指藻生长的影响,以及海带对赤潮藻生长的抑制作用。结果表明,不同的氮磷浓度及配比对三角褐指藻的生长有显著影响,氮浓度为12.35mg/L,磷浓度为1mg/L时最适宜三角褐指藻的生长;海带对三角褐指藻生长有较好的抑制作用,抑制率可达到78.8%;用海带组织培养水滤出液培养三角褐指藻7d,三角褐指藻的生长也受到明显抑制。