Third generation bioethanol from invasive macroalgae Sargassum muticum using autohydrolysis pretreatment as first step of a biorefinery

Sargassum muticum, an invasive macroalgae in Europe, was employed as material for third generation bioethanol production. As a first step, autohydrolysis was chosen as an eco-friendly pretreatment, seeking for a high enzymatic susceptibility of the solid phase and high content of hexoses as glucose, galactose and mannose, in both liquid and solid phases, which can be subsequently transformed in ethanol via fermentation. Besides, the search of a minimum consumption of energy in the pretreatment is also a key challenge in bioethanol production. At optimum conditions of autohydrolysis pretreatment, more than 90% of the glucan was recovered in the solid phase (while the other 10% appeared as glucooligosaccharides and glucose in the liquid phase). In the enzymatic hydrolysis carried out with the solid phases, glucan to glucose conversions of 94 and 89% were obtained, with the solid mixed with water and the whole slurry, respectively. Moreover, the whole slurry experiments, where all hexoses present in the raw material (glucose, galactose and mannose) from the solid and the liquid phases are fermented, allows to reach maximum ethanol yields of 80% (14.10?g of ethanol/L) referred to the theoretical yield, in a short time.
Authors are grateful to spanish Ministry of Economy andCompetitiveness (research project “Multistage projects for the in-tegral benefit of macroalgae and vegetable biomass”with referenceCTM2015-68503) and to Xunta de Galicia (Galician CompetitiveResearch Group GRC 2017/62 and to the CITACA Strategic Partner-ship), these three programs partially funded by FEDER of EuropeanUnion; to the Portuguese Foundation for Science and Technology(reference UID/BIO/04469/2019 unit), and to European RegionalDevelopment Fund under the scope of Norte2020 - ProgramaOperacional Regional do Norte (reference NORTE-01-0145-FEDER-000004).Pablo G. del Río is grateful to the Ministry of Education,Culture and Sports of Spain for his FPU research grant.
info:eu-repo/semantics/publishedVersion