A method to assess algicidal activity of microalgal extracts coupling microalgae produced in stirred closed photobioreactor operating in continuous with pulse amplitude modulated (PAM) fluorometry

Menguy, Eva; Dumontet, Vincent; Coulombier, Noémie; Meriot, Vincent; Déan, Loïc Le; Barthelemy, Vanille; Jauffrais, Thierry

doi:10.1016/j.mex.2020.101037

Cited by 3 publications

(1 citation statement)

References 15 publications

(25 reference statements)

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“…Under both pH conditions in the batch culture, Fv/Fm increased during the exponential growth phase to stabilize and decrease once the stationary phase was reached. The Fv/Fm values are similar to those previously measured for eukaryotic microalgae cultivated in similar culture conditions (Barnett et al, 2015;Goiris et al, 2015b;Jauffrais et al, 2016;Menguy et al, 2020). Yet, Fv/Fm reached a lower maximum value and decreased faster at pH 6.5 compared to pH 8.5.…”

Section: Growth Performances and Fitnesssupporting

confidence: 86%

The effects of CO2-induced acidification on Tetraselmis biomass production, photophysiology and antioxidant activity: A comparison using batch and continuous culture

Coulombier¹,

Blanchier

Déan

et al. 2021

Journal of Biotechnology

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A Tetraselmis sp. was selected for its antioxidant activity owing to its high lipid peroxidation inhibition capacity. With the aim to monitor culture conditions to improve antioxidant activity, effects of CO2-induced acidification on Tetraselmis growth, elemental composition, photosynthetic parameters and antioxidant activity were determined. Two pH values were tested (6.5 and 8.5) in batch and continuous cultures in photobioreactors. Acidification enhanced cell growth under both culture methods. However, the microalgae physiological state was healthier at pH 8.5 than at pH 6.5. Indeed, photosynthetic parameters measured with pulse amplitude modulated (PAM) fluorometry showed a decrease in the photosystem II (PSII) efficiency at pH 6.5 in batch culture. Yet, with the exception of the PSII recovering capacity, photosynthetic parameters were similar in continuous culture at both pH. These results suggest that lowering pH through CO2-induced acidification may induce a lower conversion of light to chemical energy especially when coupled with N-limitation and/or under un-balanced culture conditions. The highest antioxidant activity was measured in continuous culture at pH 6.5 with an IC50 of 3.44 ± 0.6 µg mL-1, which is close to the IC50 of reference compounds (trolox and α-tocopherol). In addition, the principal component analysis revealed a strong link between the antioxidant activity and the culture method, the photophysiological state and the nitrogen cell quota and C:N ratio of Tetraselmis sp.. These results highlight Tetraselmis sp. as a species of interest for natural antioxidant production and the potential of PAM fluorometry to monitor culture for production of biomass with a high antioxidant activity.Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site. Highlights► Tetraselmis has a higher antioxidant activity in balanced culture in acidic condition. ► CO2-acidification enhances Tetraselmis growth in batch and continuous culture. ► Culture mode and CO2-acidification have interactive effects on Tetraselmis physiology. ► CO2-acidification with N-limitation induce a decrease of photosynthetic parameters. ► CO2-acidification and culture mode are effective tools to optimize antioxidant activity.

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Section: Growth Performances and Fitnesssupporting

confidence: 86%