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G0G2422N#56788914

Abstract:

In the ongoing transition towards sustainable feedstocks, brown seaweeds have garnered attention, particularly for their wide array of antimicrobial constituents, such as polysaccharides and polyphenols [1]. This study focuses on the solubilization of these compounds from the brown seaweed Ascophyllum nodosum via microwave-assisted treatment. A main benefit of this method is the unique phenomenon where heating above the solvent’s boiling point causes an internal pressure surge, facilitating the release of the compounds of interest [2], [3]. Differing from the literature, general solubilization was investigated as the combined solubilized compounds are expected to contribute to the overall antimicrobial traits. The optimal solubilization conditions (temperature of 120°C; treatment time of 15 min and solid to liquid ratio of 1.5% SW) were determined using Response Surface Methodology (RSM) and the desirability approach by Derringer & Suich (1980). The study aimed to maximize solubilization efficiency while minimizing energy input per mass of solubilized seaweed biomass (252.3 kJ/g SSW) to obtain maximal biomass feedstock usage (67.2%), without resorting to energy-intensive conditions. Moreover, this research is the first to correlate the zeta potential and antimicrobial properties in seaweed biomass. While the literature suggested a positive correlation between zeta potential values and antimicrobial characteristics for chitosan solutions [4], no such correlation was observed for these complex extracts. Nevertheless, the extracts exhibited robust antimicrobial properties with growth inhibition by up to 97% within the 8h experiment. A significant inhibitory effect was found for the gram-positive S. aureus, but not for the gram-negative E. coli. The more pronounced effect against gram-positive bacteria might be attributed to the better accessibility of the extracted compounds through the peptidoglycan layer compared to the outer membrane of their gram-negative counterparts [5]. [1] H. U. Dahms and S. Dobretsov, “Antifouling compounds from marine macroalgae,” Marine Drugs, vol. 15, no. 9. MDPI AG, Sep. 01, 2017. [2] S. Saji, A. Hebden, P. Goswami, and C. Du, “A Brief Review on the Development of Alginate Extraction Process and Its Sustainability,” Sustainability (Switzerland), vol. 14, no. 9. MDPI, May 01, 2022. [3] D. B. Stengel and S. Connan, “Natural Products From Marine Algae Methods and Protocols Methods in Molecular Biology 1308,” 2015. [Online]. Available: http://www.springer.com/series/7651 [4] S. H. Chang, H. T. V. Lin, G. J. Wu, and G. J. Tsai, “pH Effects on solubility, zeta potential, and correlation between antibacterial activity and molecular weight of chitosan,” Carbohydr Polym, vol. 134, pp. 74–81, Dec. 2015. [5] T. F. L. Vicente, C. Félix, R. Félix, P. Valentão, and M. F. L. Lemos, “Seaweed as a Natural Source against Phytopathogenic Bacteria,” Mar Drugs, vol. 21, no. 1, p. 23, Jan. 2023.