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Research Article

Analytically monitored cultivation of Arthrospira platensis on food waste extracts to compose a sustainable, low-prized, Zarrouk-based medium

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Article: 2331067 | Received 27 Nov 2023, Accepted 11 Mar 2024, Published online: 03 Jul 2024
 

ABSTRACT

A sustainable, low-cost medium based on food waste for cultivating the cyanobacterium Arthrospira platensis (A. platensis) was investigated. Zarrouk medium components, especially phosphate, were substituted with extracts from beetroot peel, brewer’s grains, and walnut press cake. Ion concentrations of magnesium, calcium, iron, potassium, sodium, phos-phate, nitrate, sulfate, and chloride were analyzed to determine the optimal medium composition. Walnut press cake and brewer’s grains extracts showed high potential due to their magnesium, calcium, and phosphate content. Brewer’s grains extracts also provided glucose as an additional carbon source. Cultivations in shaking flasks and a photobioreactor (PBR) monitored cell growth through optical density and biomass concentration. The excess of magnesium and reduced phos-phate concentrations positively affected biomass production. A. platensis’s ability to metabolize glucose resulted in 68% higher biomass production. Growth in brewer’s grains extract required no additional phosphate. PBR cultivation showed A. platensis consumed significant magnesium and nitrate, achieving higher biomass concentrations with optimized gas exchange and light reflection systems.

Acknowledgement

We kindly thank Prof. Dr. Breithaupt from the company Hengstenberg GmbH & Co. KG (Esslingen) for giving us the opportunity to investigate beetroot peel. We further thank Mr. Kerner, owner of the Erlenbacher Ölmühle (Erlenbach) for the walnut press cake sample as well as Mr. Verdi from Gold Ochsen GmbH (Ulm) for provided us two batches of brewers grains. Their support is highly acknowledged.

Disclosure statement

No potential conflict of interest was reported by the author(s).