Collismycin C from the Micronesian Marine Bacterium Streptomyces sp. MC025 Inhibits Staphylococcus aureus Biofilm Formation.

Biofilm formation plays a critical role in antimicrobial resistance in Staphylococcus aureus . Here, we investigated the potential of crude extracts of 79 Micronesian marine microorganisms to inhibit S. aureus biofilm formation. An extract of Streptomyces sp. MC025 inhibited S. aureus biofilm formation. Bioactivity-guided isolation led to the isolation of a series of 2,2'-bipyridines: collismycin B ( 1 ), collismycin C ( 2 ), SF2738 D ( 3 ), SF2738 F ( 4 ), pyrisulfoxin A ( 5 ), and pyrisulfoxin B ( 6 ). Among these bipyridines, collismycin C ( 2 ) was found to be the most effective inhibitor of biofilm formation by methicillin-sensitive S. aureus and methicillin-resistant S. aureus (MRSA), and this compound inhibited MRSA biofilm formation by more than 90% at a concentration of 50 μg/mL. The antibiofilm activity of collismycin C was speculated to be related to iron acquisition and the presence and position of the hydroxyl group of 2,2'-bipyridines.