Abstract

Pneumonia is an acute respiratory infection that primarily affects the lungs and is caused by various microorganisms, including viruses, fungi, and bacteria. Klebsiella pneumoniae, a multidrug-resistant (MDR) and extensively drug-resistant (XDR) bacterium, is a leading cause of widespread pneumonia. This study aimed to identify endophytic bacteria from the leaves of Acalypha indica L. and evaluate their antibacterial properties through both in vitro and in silico approaches. The objectives included isolating endophytic bacteria from Acalypha indica L., testing their antibacterial activity against Klebsiella pneumo- niae, identifying the selected bacterial isolates using molecular techniques, analyzing their secondary metabolites via gas chro- matography-mass spectrometry (GC-MS), and performing in silico molecular docking studies. The study identified BE 4, an endophytic bacterial isolate of Bacillus pumilus, as exhibiting the most potent antibacterial activity against Klebsiella pneumo- niae. GC-MS analysis of the ethyl acetate extract of this isolate revealed 1,2-benzenedicarboxylic acid, bis(2-methylpropyl) ester as the primary metabolite component. Furthermore, molecular docking analysis identified two natural compound ligands, 1,2-benzenedicarboxylic acid, diethyl ester (-6.5 kcal/mol), and lilial (-6.2 kcal/mol), as having potential efficacy against drug- resistant bacteria responsible for pneumonia. These findings suggest that endophytic bacteria and their bioactive compounds could serve as promising candidates for the development of new treatments against drug-resistant pneumonia.