Abstract
We are now in the "post-antibiotic era" where there is a crucial need to develop new antibiotics with novel modes of action. Mangrove ecosystems are unique and shelter diverse halophilic microorganisms that can potentially produce novel antibacterial metabolites. In this work, extracts from four mangrove-derived isolates, namely Z3RZ1, Z3RZ3, Z3PZ1 and Z5PZ2, were tested for potential antibacterial activity against six pathogens: Escherichia coli (ATCC 25922), P. aeruginosa (ATCC 27853), Bacillus cereus (ATCC 11778), Staphylococcus aureus (ATCC 29213), Staphylococcus epidermidis (ATCC 12228) and Klebsiella pneumonia (ATCC 13883). The four extracts were tested for their antibiofilm potential against E. coli (ATCC 25922) and P. aeruginosa (ATCC 27853). The extract with the best antibiofilm activity was chemically characterized by liquid chromatography-mass spectrometry (LC-MS). Sequence analyses of the four isolates showed closest similarity matches to Micrococcus luteus (Z3RZ1), Globicatella sanguinis (Z3RZ3), Shewanella indica (Z3PZ1), and Shewanella indica (Z5PZ2). The Z3RZ3 extract had the strongest antibacterial activity against five pathogens, with the lowest minimum inhibitory concentrations (MIC) ranging from 3.91 × 102 to 6.250 × 103 µg/ml. All four extracts showed strong activity (>75%) and very strong activity (>95%) against E. coli and a P. aeruginosa biofilm formation respectively. Z3RZ3 extract was by far the most potent in disrupting pre-formed P. aeruginosa biofilms, displaying 100% efficacy within a 2-hr period. The Z3RZ3 extract contained cyclopentenones, terpenes, anthraquinone, thioinosine, cyclic lactam, benzene derivatives, and macrolides. Our study highlights the potential of the mangrove environment as a mine of new bioactive compounds with antibacterial and antibiofilm activities.
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