Comparative analysis of phycoerythrin production in cryptophytes

Léon Mercier,Anne Ojala,Elina Peltomaa

doi:10.1007/s10811-021-02657-z

Léon Mercier, Anne Ojala + Show 1 more

Open Access

https://doi.org/10.1007/s10811-021-02657-z

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Abstract

Phycobiliproteins are pigments with uses in pharmacology, cosmetics, foods, and as fluorescent probes in biochemistry. Cryptophyte microalgae are one possible source of phycobiliproteins as well as other molecules such as omega-3 fatty acids. The use of cryptophytes in biotechnology is currently very limited and especially the potential of freshwater species is poorly documented. For commercial microalgae production, it is important to find the best performing strains in terms of growth and yields of the products of interest. Phycoerythrin is a phycobiliprotein with red colour and strong yellow fluorescence. In this study, we evaluate the growth and phycoerythrin production of eight strains of freshwater cryptophytes belonging to the genus Cryptomonas, comparing them to two marine strains. The strains are grown in batch cultures under standardised conditions. Most of the studied freshwater strains have lower growth rates and all of them have lower biomass yields than the marine strains. However, most of them have much higher cellular phycoerythrin concentrations, which in the case of two strains leads them to a significantly higher overall phycoerythrin yield. There is large variation among cryptophytes in growth rates and phycoerythrin content. Our results suggest that freshwater cryptophytes of the genus Cryptomonas may be better sources of phycoerythrin than the more extensively studied marine strains.

Highlights

Phycobiliproteins (PBPs) are a group of proteinaceous pigments which form part of the light harvesting structures in red algae, cyanobacteria and cryptophyte microalgae
Freshwater strains were grown in MWC medium (Guillard and Lorenzen 1972) and marine strains in f/2 medium (Guillard and Ryther 1962) prepared using artificial sea salt
The yield of a specific compound from microalgal cultivation is the result of an interaction between the concentration of that compound in the harvested biomass and the yields of that biomass per unit of time and of culture volume. This is best represented by the yield in mg L −1 day−1 of the compound in question

Summary

Introduction

Phycobiliproteins (PBPs) are a group of proteinaceous pigments which form part of the light harvesting structures in red algae, cyanobacteria and cryptophyte microalgae. They are accessory pigments that allow these organisms to harvest light energy outside the wavelengths absorbed by chlorophyll. Phycocyanin is produced commercially using strains of cyanobacteria such as Arthrospira platensis (Eriksen 2008). Journal of Applied Phycology would enable the broader use of PBPs in dyes and colourants, potentially replacing products of petrochemical and agricultural origins that have higher environmental impacts. Cryptophytes produce several kinds of secondary metabolites that could see wide use in industry, but research on them is still scarce and most of their potential in biotechnology remains unexplored (Abidizadegan et al 2021). Between 12 and 22% of the total protein in cryptophyte cells can consist of PBPs (da Silva et al 2009; Seixas et al 2009)

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