Seaweed Extracts: A Promising Source of Antibiofilm Agents with Distinct Mechanisms of Action against Pseudomonas aeruginosa

Abstract

The organization of bacteria in biofilms is one of the adaptive resistance mechanisms providing increased protection against conventional treatments. Thus, the search for new antibiofilm agents for medical purposes, especially of natural origin, is currently the object of much attention. The objective of the study presented here was to explore the potential of extracts derived from three seaweeds: the green Ulva lactuca, the brown Stypocaulon scoparium, and the red Pterocladiella capillacea, in terms of their antibiofilm activity against P. aeruginosa. After preparation of extracts by successive maceration in various solvents, their antibiofilm activity was evaluated on biofilm formation and on mature biofilms. Their inhibition and eradication abilities were determined using two complementary methods: crystal violet staining and quantification of adherent bacteria. The effect of active extracts on biofilm morphology was also investigated by epifluorescence microscopy. Results revealed a promising antibiofilm activity of two extracts (cyclohexane and ethyl acetate) derived from the green alga by exhibiting a distinct mechanism of action, which was supported by microscopic analyses. The ethyl acetate extract was further explored for its interaction with tobramycin and colistin. Interestingly, this extract showed a promising synergistic effect with tobramycin. First analyses of the chemical composition of extracts by GC–MS allowed for the identification of several molecules. Their implication in the interesting antibiofilm activity is discussed. These findings suggest the ability of the green alga U. lactuca to offer a promising source of bioactive candidates that could have both a preventive and a curative effect in the treatment of biofilms.

Unveiling the Potential of Algal Extracts as Promising Antibacterial and Antibiofilm Agents against Multidrug-Resistant Pseudomonas aeruginosa: In Vitro and In Silico Studies including Molecular Docking

“…The results of this study demonstrated a statistically significant (p = 0.004) downregulation of algD under the combination treatment, with a decrease of 25% from 1.6 in the untreated group to 1.2 in the treated group, while there were no significant differences (p = 0.104) between the AAE and control treatment (Figure 6A). those formed in our study, have implications for chronic infections and treatment challenges, as they resist host defenses and antibiotics [8,13,27,28].…”

“…These exopolysaccharides create a protective barrier, providing bacterial tolerance against antimicrobials and the immune system [ 11 , 12 ]. P. aeruginosa biofilms, including those formed in our study, have implications for chronic infections and treatment challenges, as they resist host defenses and antibiotics [ 8 , 13 , 27 , 28 ].…”

“…These exopolysaccharides provide bacterial tolerance against antimicrobials and host immunity [ 11 , 12 ]. Bacterial biofilms, including P. aeruginosa , contribute to chronic infections, posing risks to immunocompromised individuals and those with cystic fibrosis [ 8 , 13 ]. P. aeruginosa biofilms resist antibiotics and host defenses, leading to treatment challenges and impaired immunity [ 8 , 13 ].…”

Evaluation of the STAT1 mRNA expression in peripheral blood cells as a predictive marker of early pregnancy in Awassi ewes

“…Following the removal of any excess dye with distilled water, 200 µl of 95% (v/v) ethanol was added once the wells were dried. The following formula was used to determine the biofilm inhibition activity after which the optical density at 630 nm was measured in a multi-plate reader [24]. % biofilm inhibition = (OD of untreated isolate -OD of untreated isolate/ OD of treated isolate) ×100…”

Discovery of potent 1,1-diarylthiogalactoside glycomimetic inhibitors of Pseudomonas aeruginosa LecA with antibiofilm properties

“…Data quality and refinement statistics are described in Table 2. [29,[55][56] P. aeruginosa PAO1 (CIP 104116) was obtained from the Institute Pasteur collection (Paris, France). The strain was frozen and kept at -80°C.…”