High Productivity of Eicosapentaenoic Acid and Fucoxanthin by a Marine Diatom Chaetoceros gracilis in a Semi-Continuous Culture.

Saki Tachihana,Tomoyo Katayama,Sanjoy Banerjee,Tatsuki Toda,Norio Nagao,Mohamed Shariff,Norio Kurosawa,Minamo Hirahara,Fatimah Md Yusoff,Ken Furuya

doi:10.3389/fbioe.2020.602721

Abstract

Significantly high eicosapentaenoic acid (EPA) and fucoxanthin contents with high production rate were achieved in semi continuous culture of marine diatom. Effects of dilution rate on the production of biomass and high value biocompounds such as EPA and fucoxanthin were evaluated in semi-continuous cultures of Chaetoceros gracilis under high light condition. Cellular dry weight increased at lower dilution rate and higher light intensity conditions, and cell size strongly affected EPA and fucoxanthin contents. The smaller microalgae cells showed significantly higher (p < 0.05) value of 17.1 mg g-dw–1 fucoxanthin and 41.5% EPA content per total fatty acid compared to those observed in the larger cells. Chaetoceros gracilis can accumulate relatively higher EPA and fucoxanthin than those reported previously. In addition, maintenance of small cell size by supplying sufficient nutrients and light energy can be the key for the increase production of valuable biocompounds in C. gracilis.

Highlights

Microalgae have been utilized for the production of high value-added compounds such as carotenoids (Foo et al, 2015, 2017) and poly unsaturated fatty acids (PUFA) including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (Chrismadha and Borowitzka, 1994; Yang et al, 2017)
The steady state of both cell density and cell physiology could not be attained at a dilution rate of 0.1 d−1 suggesting that both consistent cell quality and stable biomass production rate could not be achieved in the actual production process for commercialization
High PUFA content of 60% and significant high EPA contents of 41.5% in total fatty acid was associated with small cells of C. gracilis. These results indicated that cell size affects PUFA, mainly EPA, indicating that maintenance of small cellular dry weight is the key operation factor for effective production of EPA

Summary

Introduction

Microalgae have been utilized for the production of high value-added compounds such as carotenoids (Foo et al, 2015, 2017) and poly unsaturated fatty acids (PUFA) including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (Chrismadha and Borowitzka, 1994; Yang et al, 2017). Diatoms are known to be efficient producers of fucoxanthin and EPA, and have been widely used in aquaculture for feeding juvenile fish and shrimp to improve growth rate, survival rate and nutritional value (Enright et al, 1986). Microalgae with high EPA and fucoxanthin contents have the potential to be used in food, cosmetic and pharmaceutical industries. Productivity of EPA and Fucoxanthin and anti-obesity effects on humans (Kanazawa, 2012). There is a need for technological development to enhance valuable compounds production by diatoms to meet high social and economic demands (Krichnavaruk et al, 2007; Monkonsit et al, 2011; Kaspar et al, 2014)

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