Innovative processing of brown seaweed for value-added products
Summary, in English
In this research, various pre-treatment methods, including acid, heat, and enzymatic treatment, were performed to solubilize carbohydrates from brown seaweed for subsequent biorefinery utilization. The extracts from acid and heat treatment of Laminaria digitata showed its potential to be used as feed for cultivating thermophilic bacteria, such as Rhodothermus marinus and Bacillus methanolicus, respectively, which are able to produce bioactive compounds and can be used as microbial cell factories, demonstrating the suitability of the extracts for replacing terrestrial carbohydrates for bacterial cultivation.
Biofuel production through fermentation using various microbes, revealed that Thermoanaerobacterium AK17 could utilize not only glucose but also mannitol and glucans released by enzymatic treatment of the brown seaweed L. digitata in ethanol production. Additionally, Clostridial strains studied in this thesis showed different nutrient requirements, but, however, they were able to utilize glucan and mannitol available in the L. digitata hydrolysates for the production of acetone/isopropanol, butanol, and ethanol (A/IBE).
A lactic acid bacteria consortium was shown to be able to ferment mannitol from A. esculenta. This could be a way to increase the shelf life of the seaweed, an alternative to current storage techniques.
Laminarin is a glucan composed of β-1,3(6) linked glucose unit and is a storage carbohydrate in brown seaweed. Enzymes capable of degrading and modifying laminarin and laminari-oligosaccharides were explored for potential valorization of this glucan. In this study, two novel GH17 enzymes were identified in the marine bacterium Muricauda lutaonensis; one is an endo-acting laminarinase, capable of degrading laminarin into short-chain oligosaccharides with a degree of polymerization (DP) 2-4, with potential prebiotic properties. The other is β-1,3-glucanosyltransglycosylase which utilizes β-1,3 linked oligosaccharides with DP above 5 as a donor to introduce β-1,6 linked branches or kinks into β-1,3-glucans, which have potential bioactive properties.
These findings collectively offer invaluable insights into the potential of brown macroalgae as a renewable, sustainable source for biofuels and value-added biomolecules.
- ISBN: 978-91-8096-010-6
- ISBN: 978-91-8096-011-3
15 december 2023
Lecture Hall KC:A, Kemicentrum, Naturvetarvägen 14, Faculty of Engineering LTH, Lund University, Lund
- Øystein Arlov (Senior Research.)