Year-Round Cultivation of Tetraselmis sp. for Essential Lipid Production in a Semi-Open Raceway System

Won-Kyu Lee,Woon-Yong Choi,Yeon-Ji Lee,Younsik Jeong,Do-Hyung Kang,Areumi Park,Yong-Kyun Ryu,Taeho Kim,Choul-Gyun Lee

doi:10.3390/md19060314

Abstract

There is increasing demand for essential fatty acids (EFAs) from non-fish sources such as microalgae, which are considered a renewable and sustainable biomass. The open raceway system (ORS) is an affordable system for microalgae biomass cultivation for industrial applications. However, seasonal variations in weather can affect biomass productivity and the quality of microalgal biomass. The aim of this study was to determine the feasibility of year-round Tetraselmis sp. cultivation in a semi-ORS in Korea for biomass and bioactive lipid production. To maximize biomass productivity of Tetraselmis sp., f medium was selected because it resulted in a significantly higher biomass productivity (1.64 ± 0.03 g/L) and lower omega-6/omega-3 ratio (0.52/1) under laboratory conditions than f/2 medium (0.70/1). Then, we used climatic data-based building information modeling technology to construct a pilot plant of six semi-ORSs for controlling culture conditions, each with a culture volume of 40,000 L. Over 1 year, there were no significant variations in monthly biomass productivity, fatty acid composition, or the omega-6/omega-3 ratio; however, the lipid content correlated significantly with photosynthetic photon flux density. During year-round cultivation from November 2014 to October 2017, areal productivity was gradually increased by increasing medium salinity and injecting CO2 gas into the culture medium. Productivity peaked at 44.01 g/m2/d in October 2017. Throughout the trials, there were no significant differences in average lipid content, which was 14.88 ± 1.26%, 14.73 ± 2.44%, 12.81 ± 2.82%, and 13.63 ± 3.42% in 2014, 2015, 2016, and 2017, respectively. Our results demonstrated that high biomass productivity and constant lipid content can be sustainably maintained under Korean climate conditions.

Highlights

Microalgae have received increasing interest as a biofuel resource in response to the rising energy crisis, depletion of fossil fuels, and climate change [1,2]
Microorganisms have been proposed as a feedstock for the production of bioactive compounds, including β-carotene, phycobilin pigments, fatty acids (FAs), and amino acids [3,4,5,6,7]
The aim of this study was to report the feasibility of biomass and bioactive lipid production from Tetraselmis sp. in semi-open raceway system (ORS) in Korea over a 3-year period

Summary

Introduction

Microalgae have received increasing interest as a biofuel resource in response to the rising energy crisis, depletion of fossil fuels, and climate change [1,2]. Microorganisms have been proposed as a feedstock for the production of bioactive compounds, including β-carotene, phycobilin pigments, fatty acids (FAs), and amino acids [3,4,5,6,7]. Microalgae can be used in the bio-refinery process to produce high-value products that can increase the opportunities and possibilities for various industries [8]. Tetraselmis (Chlorophyta), which has previously been reported to contain a substantial lipid fraction, is a potentially promising bioactive feedstock, like other microalgal species [9,10]. Polyunsaturated fatty acids (PUFAs), such as omega-3 (ω-3) and omega-6. Humans must acquire PUFAs through their diet [17]

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Methods

Discussion

Conclusion