Antibacterial Effect of an Ethyl Acetate Extract of Emericella nidulans Derived from Endophytic Fungus Rhizophora mucronata Against Methicillin-Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant global public health challenge due to its resistance to conventional antibiotics, leading to persistent infections, increased healthcare costs, and high mortality rates. MRSA can cause various diseases, including those affecting the skin, subcutaneous tissues, and internal organs. Its resistance is largely driven by the mecA gene, which encodes Penicillin Binding Protein 2a (PBP2a), which prevents β-lactam antibiotics from effectively targeting the bacterial cell wall. In this study, crude extract and fractions of Emericella nidulans derived from Rhizophora mucronata mangrove were prepared and screened for antibacterial activity against MRSA. In vitro tests on ethyl acetate extracts and fractions of E. nidulans revealed that they can inhibit MRSA growth in a moderate range. The crude extracts were analyzed using liquid chromatography-high-resolution mass spectrometry (LC-HRMS) to determine the compound contained. Forty-eight compounds were screened through molecular docking analysis to identify the bioactive compounds inhibiting the SauPBP2a receptor. It is indicated that E. nidulans shows promise as raw materials for antibacterial against MRSA. HIGHLIGHTS Ethyl acetate extract of nidulans showed antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) in vitro and contained 47 compounds based on LC-HRMS analysis. In silico studies predicted nine compounds such as 1-linoleoyl glycerol, 9-oxo-10(E),12(E)-octadecadienoic acid, monoolein, methyl ester of 9(Z),11(E),13(E)-octadecadienoic acid, bis(4-ethylbenzylidene) sorbitol, α-linolenic acid, and oleamide have ability to inhibit the SauPBP2a receptor. GRAPHICAL ABSTRACT