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Advisor(s)
Abstract(s)
ABSTRACT - Green macroalgae, e.g., Ulva lactuca, are valuable bioactive sources of nutrients; but algae recalcitrant cell
walls, composed of a complex cross-linked matrix of polysaccharides, can compromise their utilization as
feedstuffs for monogastric animals. This study aimed to evaluate the ability of pre-selected Carbohy-
drate-Active enZymes (CAZymes) and sulfatases to degrade U. lactuca cell walls and release nutritive
compounds. A databank of 199 recombinant CAZymes and sulfatases was tested in vitro for their action
towards U. lactuca cell wall polysaccharides. The enzymes were incubated with the macroalga, either
alone or in combination, to release reducing sugars and decrease fluorescence intensity of Calcofluor
White stained cell walls. The individual action of a polysaccharide lyase family 25 (PL25), an ulvan lyase,
was shown to be the most efficient in cell wall disruption. The ulvan lyase treatment, in triplicate
measures, promoted the release of 4.54 g/L (P < 0.001) reducing sugars, a mono- and oligosaccharides
release of 11.4 and 11.2 mmol/100 g of dried alga (P < 0.01), respectively, and a decrease of 41.7%
(P < 0.001) in cell wall fluorescence, in comparison to control. The ability of ulvan lyase treatment to
promote the release of nutritional compounds from alga biomass was also evaluated. A release of some
monounsaturated fatty acids was observed, particularly the health beneficial 18:1c9 (P < 0.001). How-
ever, no significant release of total fatty acids (P > 0.05), proteins (P ¼ 0.861) or pigments (P > 0.05) was
found. These results highlight the capacity of a single recombinant ulvan lyase (PL25 family) to
incompletely disrupt U. lactuca cell walls. This enzyme could enhance the bioaccessibility of U. lactuca
bioactive products with promising utilization in the feed industry.
Description
Research Areas: Agriculture; Veterinary Sciences
Keywords
Macroalga Ulva lactuca Carbohydrate-active enzyme Ulvan lyase Cell wall degradation
Pedagogical Context
Citation
Costa MM, Pio LB, Bule P, Cardoso VA, Duarte M, Alfaia CM, Coelho DF, Bras JA, Fontes CMGA, Prates JAM . 2022. Recalcitrant cell wall of Ulva lactuca seaweed is degraded by a single ulvan lyase from family 25 of polysaccharide lyases. Animal Nutrition, 9:p.184-192. DOI: https://doi.org/10.1016/j.aninu.2022.01.004
Publisher
KEAI PUBLISHING