Variations in Physicochemical Properties and Bioconversion Efficiency of Ulva lactuca Polysaccharides After Different Biomass Pretreatment Techniques
Green macroalgae are an abundant and undervalued biomass with a specific cell wall structure. In this context, different pretreatments, namely ethanol organosolv (Org), alkaline, liquid hot water (LHW), and ionic liquid (IL) pretreatments, were applied to the green macroalgae Ulva lactuca biomass and then evaluated. Their effects on chemical composition, biomass crystallinity, enzymatic digestibility, and theoretical ethanol potential were studied. The chemical composition analysis showed that the Org and LHW pretreatments allowed the highest glucan recovery (80.8 ± 3.6 and 62.9 ± 4.4 g/100 g DM, respectively) with ulvan (80.0 and 99.1%) and hemicellulose (55.0 and 42.3%) removal. These findings were in agreement with both thermogravimetric analysis and scanning electron microscopy results that confirm significant structural changes of the pretreated biomasses. It was found that the employed pretreatments did not significantly affect the cellulose crystallinity; however, they both increased the whole crystallinity and the enzymatic digestibility. This later reached 97.5% in the case of LHW pretreatment. Our results showed high efficiency saccharification of Ulva lactuca biomass that will constitute the key step of the implementation of a biorefinery process.
KeywordsGreen macroalgae Pretreatment Crystallinity Enzymatic hydrolysis Ulva lactuca
1-ethyl-3- methylimidazolium- acetate
High-performance anion exchange chromatography coupled to pulsed amperometric detection
Liquid hot water
Scanning electron microscopy
This work was carried out as a part of the ALGAEVAL project (TUNGER – 72) jointly funded by the German Federal Ministry of Education and Research (BMBF) and the Tunisian Ministry for Higher Education and Scientific Research (MESRS).
Part of this work was performed as part of the Cluster of Excellence “Tailor-Made Fuels from Biomass,” which is funded by the Excellence Initiative of the German federal and state governments to promote science and research at German universities.
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflicts of interest.
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