Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Producing algae in the Qatari desert : from strain to process

Auteur : Schipper, Kira

Université de soutenance : Wageningen University

Grade : Doctor 2021

Résumé partiel
The Arabian Peninsula, due to its climate, availability of non-arable land, seawater, and carbon dioxide, is one of the best global locations for commercial cultivation of algae and cyanobacteria. This work focused on the screening of multiple locally isolated strains for their capability to thrive under industrially relevant conditions of elevated temperatures (up to 40 ˚C) and carbon dioxide levels (up to 30%). Two strains, Leptolyngbya sp. and Picochlorum sp., grew well at temperatures of up to 40 ˚C, and also showed a tolerance towards elevated CO2 concentrations. Both microalgae isolated, T. subcordiformis and Picochlorum sp., presented significant amounts of lipids, including high-value omega-3 fatty acids EPA and DHA. On the other hand, both cyanobacteria, Leptolyngbya sp. and Chroococcidiopsis sp., presented levels of phycobiliproteins. The isolates, all very diverse in response and products, showed promising characteristics, making them valuable strains for further investigation towards commercial applications and CO2 capture.

One of the identified cyanobacteria was further investigated for its potential to produce phycocyanin, a nutraceutical with high commercial value, under desert climate conditions. Under elevated temperatures and light intensities, of up to 40 ˚C and 1800 µmol photons·m-2·s-1, Leptolyngbya sp. biomass productivity was up to 45% higher as compared A. platensis, the commercially most commonly produced strain for phycocyanin. High temperatures were found to improve both the biomass productivity and phycocyanin content, with maxima of 1.09±0.03 gX·L-1·d-1 and 72.12±3.52 mgPC·gX-1, respectively. Furthermore, various cell disruption methods and buffers were tested for the efficient extraction of high-purity phycocyanin. The best results were found through bead-beating in phosphate buffer, which showed the highest combined phycocyanin yield (169.9±3.6 mgPC·gX) and purity (7.37±0.16). The extract purities obtained for Leptolyngbya sp. are considerably higher than other reported phycocyanin purities. This, together with the strains capability to maintain relatively high biomass productivities compared to A. platensis, even under such high light intensities, make it a feasible candidate for high-value phycocyanin production in desert environments.

Présentation