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

Mari Carmen Ruiz-Domínguez,Pedro Cerezal-Mezquita,Bárbara Rincón,Elena Medina,Marí Ángeles Martín,Marí Carmen Gutiérrez,Francisca Salinas

doi:10.3390/md20020127

Abstract

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.

Highlights

IntroductionDiatoms are unicellular photosynthetic eukaryotes that are commonly found in marine ecosystems and moist terrestrial habitats
Licensee MDPI, Basel, Switzerland.Diatoms are unicellular photosynthetic eukaryotes that are commonly found in marine ecosystems and moist terrestrial habitats
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Summary

Introduction

Diatoms are unicellular photosynthetic eukaryotes that are commonly found in marine ecosystems and moist terrestrial habitats. They contribute to about 20–25% of global carbon dioxide fixation through photosynthesis and play an important role in the global silicon cycle [1,2]. They are a part of the base of marine trophic networks worldwide and contribute to at least 20% of annual primary productivity, which is equivalent to tropical forests [3,4]. Novel and green applications have been discovered from intracellular molecules present in diatoms such as total lipids for biodiesel and amino acids for cosmetic, antibiotic, and antiproliferative agents or bioremediation uses [6,7,8]

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