Native extremophilic marine cyanobacteria strains from Qatar represent promising candidates for large scale outdoor cultivation in desert environments, taking advantage of the local solar, seawater and CO 2 resources. In this study, a recently isolated pigment producing Pleurocapsa sp. strain was successfully cultivated in open ponds using urea as an inexpensive local nitrogen source, producing biomass with up to 12% dry weight of phycobiliproteins, predominantly phycocyanin. Following pigment extraction, the residual biomass was valorized via hydrothermal conversion, demonstarting the feasibility of obtaining bitumen-like oil fractions. However, this result that opens perspectives for optimized biorefinery, was shown to require a pigment extraction process allowing the simultaneous reduction of the ash content in the biomass, which is about three-fold higher than that of a spirulina biomass reference cultivated in France. Indeed, the reduction in biomass ash content had a significant impact on the hydrothermal conversion oil yield, but also on the oil's chemical composition in terms of molecular mass distribution, and on the resulting material's rheology. The bitumen-like thermo-rheological behavior of the oils appears to be associated with the presence of a significant fraction of molecules above 1000 g/mol, in addition to a dominant population around 300 g/mol. It was further validated by the successful fitting of experimental data using a rheological model originally developed for conventional petroleum bitumen. These findings highlight the potential of Qatar's native extremophillic cyanobacteria for integrated pigment production and optimized algal biorefineries in arid regions. • A local extremophilic marine cyanobacterium was cultivated outdoor in Qatar desert. • Biomass produced shows high contents in valuable phycobiliproteins but also ashes. • Pigment extraction process can be tuned for reducing ash content in biomass. • Hydrothermal conversion of low ash residues leads to bitumen like oil phases. • Thermorheological behavior is described by a model developed for petroleum bitumen.
Bounnit et al. (Fri,) studied this question.