Antibacterial Potential of Epiphytic Fungi From Kenyan Brown Algae

• The report addresses the urgent need for new antimicrobial agents in the face of rising resistance and slow development of therapeutics.
• It focuses on marine fungi, specifically epiphytic yeasts and molds residing on brown algae along the Kenyan coast, as a source of potential bioactive secondary metabolites aimed at multidrug-resistant pathogens.
• The objective was to assess antibacterial properties of fungal epiphytes associated with coastal brown algae against multidrug-resistant organisms.

• Epiphytic fungi were isolated from brown seaweeds collected along the Kenyan coastline.
• Identification combined morphological assessment with ITS-based molecular methods.
• Phylogenetic analyses aligned the isolates with genera known for producing bioactive metabolites, consistent with observed morphological and growth characteristics.

• An initial screening identified nine potent and broadly active isolates for further testing.
• The evaluation extended to activity against a panel of multidrug-resistant ESKAPE pathogens: Enterobacter cloacae, Acinetobacter baumannii, Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa.
• From these, the most active extracts were further characterized using scanning electron microscopy (SEM) and chemical profiling by GC-MS.

(Dib-4), Curvularia spp.

(Dib-3), and Penicillium spp.

(Sac-12).

• Both methanolic and ethyl acetate extracts demonstrated antibacterial activity, with zones of inhibition spanning 14 to 30.40 mm.
• Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values reached as low as 0.039 mg/mL and 0.156 mg/mL, respectively, with notable performance from extracts of Alternaria spp.
• Some isolates showed moderate or selective activity rather than broad potency.
• SEM revealed bacterial cell envelope damage, including membrane blebbing, collapse, and lysis, suggesting a potential membrane-targeting mechanism of action.

• GC-MS analysis detected a variety of bioactive metabolites in the active extracts.
• The results position brown seaweed surface–associated fungi from the Kenyan coast as an underexplored reservoir of antibacterial constituents with activity against multidrug-resistant bacteria.
• The observed solvent dependence for compound recovery highlights the importance of extraction method in accessing active constituents.

• The report indicates variability in activity across isolates, with some showing limited inhibitory effects.
• Specific structural identities of active compounds beyond broad taxonomic assignment were not detailed in this summary, and functional in vivo relevance remains to be established.