Antibacterial and Antibiofilm Activities of Red Sea Sponge Extracts: Exploring the Potential of Dactylospongia metachromia and Suberites aff. clavatus Against Gram-Positive Pathogens

Objectives Marine sponges, such as Dactylospongia metachromia and Suberites aff. clavatus from the Red Sea have emerged as potential sources of bioactive compounds with significant antimicrobial properties. Methods This study investigates the antibacterial and antibiofilm activities of methanol–dichloromethane extracts from these sponges against clinically relevant strains of Gram-positive bacteria, including Staphylococcus aureus , Methicillin-resistant Staphylococcus aureus , and Staphylococcus epidermidis , as well as Gram-negative pathogens like Pseudomonas aeruginosa and Escherichia coli using agar well diffusion, broth microdilution, biofilm inhibition/eradication assays, scanning electron microscopy (SEM), and LC-MS profiling. Results The results revealed that the extract of Dactylospongia metachromia exhibited promising antibacterial activity, particularly against Gram-positive strains, with a significant zone of inhibition and moderate bactericidal effects, indicated by MICs of 250 µg/mL for both Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus . In contrast, Suberites aff. clavatus showed minimal antibacterial activity. Additionally, Dactylospongia metachromia demonstrated effective inhibition and eradication of biofilm formation, particularly against Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus . Scanning electron microscope images further revealed rupture of the bacterial membrane. LC-MS tentatively identified smenospongine as a major antibacterial component, while metachromin H and nakijiquinone J showed no reported antimicrobial activity. Suberites aff. clavatus showed minimal activity. Conclusion These findings suggest that Dactylospongia metachromia could be a valuable source for developing new treatments for skin infections caused by antibiotic-resistant bacteria, while Suberites aff. clavatus may require further exploration for its bioactive compounds. This study highlights the therapeutic potential of Red Sea sponges and supports the need for continued research into marine natural products for antimicrobial drug development.