Electrochromic Properties and Electrochemical Behavior of Marennine, a Bioactive Blue-Green Pigment Produced by the Marine Diatom Haslea ostrearia

Abstract

Marennine has long been known as the unique peculiar pigment responsible for the natural greening of oysters. It is specifically produced by the marine diatom Haslea ostrearia and it is a natural blue molecule indeed promising for food industry because of the rarity of such non-toxic, blue-colored pigments. In the search for its still not defined molecular structure, investigation of the color changes with the redox state has been carried out combining different approaches. Reducing and oxidizing chemicals have been added to purified marennine solutions and a stable blue-green color has been confirmed for the oxidized state, while a yellow color corresponded to the reduced unstable state. Raman spectroscopy has been used to monitor changes in the Raman spectra corresponding to the different colored states, and cyclic voltammetry has allowed the detection of a redox system in which protons and electrons are exchanged. These findings show that marennine is a suitable stable blue pigment for use in food applications and help in the elucidation of the chromophore structure.

The Polysaccharidic Nature of the Skeleton of Marennine as Determined by NMR Spectroscopy

“…It is known that polysaccharides, among them EPS, can attract metal ions [ 41 ], and these might be the origin of the color. On the other hand, cyclic voltammetry curves of the redox system identified as being related to a change of the color indicate an exchange of protons and electrons at the same time upon redox reactions, which is rather compatible with a molecule containing quinone groups than with metallic cations [ 47 ].…”

“…The extraction and purification as well as the hydrolysis was repeated many times with varying protocols in order to manifest the correlation between glycosidic NMR signals and the color. Extracellular marennine (EMn) was obtained using two purification procedures associated with two different size cultures of Haslea ostrearia : <20 L (small-scale marennine production) as described in Francezon et al [ 47 ], and >100 L (scale-up production) as described by Turcotte et al [ 14 ]. For small-scale production, algae were grown in 40 × 500 mL Erlenmeyer flasks [ 47 ], up to the beginning of the plateau phase (2–3 weeks).…”

“…Extracellular marennine (EMn) was obtained using two purification procedures associated with two different size cultures of Haslea ostrearia : <20 L (small-scale marennine production) as described in Francezon et al [ 47 ], and >100 L (scale-up production) as described by Turcotte et al [ 14 ]. For small-scale production, algae were grown in 40 × 500 mL Erlenmeyer flasks [ 47 ], up to the beginning of the plateau phase (2–3 weeks). Then the supernatants containing EMn were pooled and EMn was concentrated by precipitation using chemicals (quick and suitable for lab scale batch, see below).…”

Submerged membrane photobioreactor for the cultivation of Haslea ostrearia and the continuous extraction of extracellular marennine

“…So far H. ostrearia has been mainly cultivated in open culture systems of 200 L and 10 m 3 or in photobioreactors (PBRs, less than7 L) (Gastineau et al, 2014b;Rossignol et al, 2000a;Turpin et al, 2001). Whatever the system, high volumes of culture often have to be set-up in order to produce a consistent amount of biomass or marennine, as their concentrations are usually low (Bélanger et al, 2020;Francezon et al, 2021). Thus, cultivation process intensification remains a challenge, notably to increase marennine or biomass concentration but also the productivities.…”

The blue diatom Haslea ostrearia from the Indian Ocean coast of South Africa, with comparative analysis of Haslea organellar genomes

“…During the austral-spring of 2018, a blue-tipped diatom, identified as Haslea ostrearia (Gaillon) Simonsen (Simonsen, 1974;Poulin et al, 2019), was isolated from the plankton net sample originating from the Kei Mouth rock pools. The blue diatom H. ostrearia is a marine species famous for synthesizing marennine, a blue pigment displaying several biological activities and whose exact chemical structure remains unknown (Pouvreau et al, 2006;Pouvreau et al, 2008;Gastineau et al, 2012a;Gastineau et al, 2014b;Prasetiya et al, 2015;Gastineau et al, 2018;Prasetiya et al, 2019a;Prasetiya et al, 2020;Prasetiya et al, 2021a;Prasetiya et al, 2021b;Francezon et al, 2021). Haslea ostrearia is a benthic/tychopelagic species famous for the 'greening' effect of its blue pigment on the natural benthic habitat (e.g., macroalgae or sand, rocks etc.)…”