Selective fractionation of free glucose and starch from microalgae using aqueous two-phase systems

Catalina A Suarez Ruiz,Santiago Zarate Baca,Lambertus A.M Van Den Broek,Corjan Van Den Berg,Rene H Wijffels,Michel H.M Eppink

doi:10.1016/j.algal.2020.101801

Catalina A Suarez Ruiz, Santiago Zarate Baca + Show 4 more

Open Access

https://doi.org/10.1016/j.algal.2020.101801

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Abstract

Microalgae are a promising source of lipids, pigments, proteins and carbohydrates, which are valuable compounds for many industries. However, optimal fractionation and valorization of all produced compounds is necessary to improve the economic viability of microalgae production. This paper aims to understand the fractionation of microalgae carbohydrates (free glucose and starch) in aqueous two-phase systems. Three aqueous two-phase systems were investigated to efficiently and mildly separate carbohydrates from disrupted Neochloris oleoabundans. This strain contains 16 w/w% of proteins, 48 w/w% total fatty acids and 27 w/w% carbohydrates when cultivated under saline water and nitrogen depletion conditions. The protein content decreases and the amount of fatty acids and carbohydrates increases notably under stress conditions and glucose becomes the main carbohydrate in this microalgae. Glucose is present in the disrupted microalgae as part of polymeric carbohydrates (starch) or in monomeric form (free glucose). With the aqueous two-phase system Polyethylene Glycol 400 - Cholinium dihydrogen phosphate (PEG400-ChDHp) microalgal free glucose is fractionated up to a recovery of 99% to the most hydrated bottom phase in a single step. Simultaneously, a recovery of 70% is reached for microalgal starch in the interface after two additional liquid-liquid extractions with PEG400-ChDHp. The final fractions obtained were free of pigments.

Highlights

Carbohydrates derived from renewable biomass are a promising and sustainable alternative for the petroleum-based products that are used in diverse applications
Table 2. presents the biochemical composition of N. oleoabundans cultivated under four different conditions
The increase of carbohydrates and lipids in this microalgae has previously been used as a strategy to provide a more economically feasible scenario for microalgal-based biofuels [38,41]

Summary

Introduction

Carbohydrates derived from renewable biomass are a promising and sustainable alternative for the petroleum-based products that are used in diverse applications (e.g. renewable energy, commodity chemicals, bioplastics, food and feed additives). For these purposes, microalgae have received increased attention [1,2,3,4]. Microalgae have received increased attention [1,2,3,4] These microorganisms can accumulate up to 60% carbohydrates, depending on the species, growth and environmental conditions [5]. Carbohydrates are a promising ingredient for the food and animal feed industries [9] and for the production of new materials such as biopolymers [10] or used as fermentation feedstock to produce hydrocarbons, lower alcohols, diols and carboxylic acids [11]

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