Room-Temperature Cell Disruption and Astaxanthin Recovery from Haematococcus lacustris Cysts Using Ultrathin α-Quartz Nanoplates and Ionic Liquids

Nakyeong Lee,Rendi Mahadi,Gyuseop Moon,Myeonghwa Park,Aditya Lakshmi Narasimhan,Bolam Kim,You-Kwan Oh,Sungwook Chung,Young-Eun Kim

doi:10.3390/app12042210

Abstract

Ionic liquids (ILs) are new green solvents, which are widely used in lignocellulosic and microalgal biorefineries. However, high-temperature operating conditions limit their application in the extraction of heat-labile algal products, such as bioactive astaxanthin. In this study, we report the technical feasibility of room-temperature astaxanthin extraction from Haematococcus lacustris cysts with a thick and complex cell wall structure, by combining ultrathin α-quartz nanoplates (NPLs) with ethyl-3-methylimidazolium ([Emim])-based ILs. When four different [Emim]-based ILs with thiocyanate (SCN), diethylphosphate (DEP), HSO4, and Cl anions were applied to 90-day-old H. lacustris cysts at room temperature (~28 °C), the astaxanthin extraction efficiency was as low as 9.6–14.2%. Under sonication, α-quartz NPLs disrupted the cyst cell wall for a short duration (5 min). The astaxanthin extraction efficacies of a subsequent IL treatment improved significantly to 49.8% for [Emim] SCN, 60.0% for [Emim] DEP, 80.7% for [Emim] HSO4, and 74.3% for [Emim] Cl ions, which were 4.4, 6.1, 8.4, and 5.2 times higher than the extraction efficacy of only ILs, respectively. This finding suggests that α-quartz NPLs can serve as powerful cell-wall-disrupting agents for the room-temperature IL-mediated extraction of astaxanthin from robust algal cyst cells.

Highlights

Astaxanthin (3,3 -dihydroxy-β,β -carotene-4,4 -dione), a secondary ketocarotenoid phytopigment, is widely used in the cosmetic, aquaculture, food, and pharmaceutical industries [1,2]
Astaxanthin accumulates in H. lacustris as neutral lipid bodies, primarily in monoand di-ester forms with fatty acids, during the physiological development of dormant aplanospores from vegetative palmella cells under conditions of stress, such as nutrient deprivation, pH shock, high salinity, strong light irradiance, and nanoparticle exposure [4,10,11]
Cell encystment is accompanied by the formation of a rigid multilayered cell wall structure

Summary

Introduction

Astaxanthin (3,3 -dihydroxy-β,β -carotene-4,4 -dione), a secondary ketocarotenoid phytopigment, is widely used in the cosmetic, aquaculture, food, and pharmaceutical industries [1,2]. Astaxanthin has been proposed as a potential geroprotector that may affect the rate of human aging and extend cell longevity [5]. This biomolecule can induce the synthesis of hyaluronan (hyaluronic acid), which is related to skin hydration [6]. Astaxanthin accumulates in H. lacustris as neutral lipid bodies, primarily in monoand di-ester forms with fatty acids, during the physiological development of dormant aplanospores (cysts) from vegetative palmella cells under conditions of stress, such as nutrient deprivation, pH shock, high salinity, strong light irradiance, and nanoparticle exposure [4,10,11]. The cell wall thickness (~4 μm) of H. lacustris cysts is significantly greater than that of Chlamydomonas (~351 nm), which is extensively used in various algal biorefineries [12,13,14]

Objectives

Methods

Results