Browsing by Author "Sheahan, Con"
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- Evaluation of the ethanol tolerance for wild and mutant Synechocystis strains by flow cytometryPublication . Silva, Teresa Lopes da; Passarinho, Paula; Galriça, Ricardo; Zenóglio, Afonso; Armshaw, Patrícia; Pembroke, J. Tony; Sheahan, Con; Reis, Alberto; Gírio, FranciscoABSTRACT: Flow cytometry was used to evaluate the effect of initial ethanol concentrations on cyanobacterial strains of Synechocystis PCC 6803 [wild-type (WT), and ethanol producing recombinants (UL 004 and UL 030)] in batch cultures. Ethanol recombinants, containing one or two metabolically engineered cassettes, were designed towards the development of an economically competitive process for the direct production of bioethanol from microalgae through an exclusive autotrophic route. It can be concluded that the recombinant Synechocystis UL 030 containing two copies of the genes per genome was the most tolerant to ethanol. Nevertheless, to implement a production process using recombinant strains, the bioethanol produced will be required to be continuously extracted from the culture media via a membrane-based technological process for example to prevent detrimental effects on the biomass. The results presented here are of significance in defining the maximum threshold for bulk ethanol concentration in production media.
- Process simulation and techno-economic assessment for direct production of advanced bioethanol using a genetically modified Synechocystis sp.Publication . Lopes, Tiago; Cabanas, Catarina; Silva, André; Fonseca, Diana; Santos, Edgar; Guerra, L. Tiago; Sheahan, Con; Reis, Alberto; Gírio, FranciscoABSTRACT: A techno-economic assessment for the direct production of ethanol using a genetically-modified microalgae has been studied. It was considered two main scenarios for process modelling: i) bioenergy-driven microalgae plant, i.e., focused on the production of fuel-grade ethanol and biogas for CHP and, ii) biorefinery-driven microalgae plant, focused on the recovery of added-value bioproducts (zeaxanthin and phycocyanin) along with ethanol and CHP production. These main scenarios and several variants were modelled and optimized for a small-scale demo plant of 1000 Lethanol/day and extrapolated for larger production capacities. Results showed that despite the innovative approach of direct production of ethanol by microalgae, the bioenergy-driven scenario is non-feasible under the studied conditions. Conversely, ethanol production becomes economically feasible as co-product in the biorefinery-driven scenario although having payback periods>10 years. Furthermore, if only bio-based products are produced the NPV and the payback are even more positive, 104.8 M€ and ca. 5 years, respectively.