Antimicrobial Activities of Symbiotic and Non-symbiotic Bacteria Associated with the Entomopathogenic Nematode, Steinernema feltiae

Abstract

The use of antibiotics against a range of pathogenic bacteria has increased in recent years, leading to the development of drug resistance, which makes disease control challenging. Thus, the need for the development of new antibacterial medications is critical. Natural resources, such as entomopathogenic bacteria (EPB), provide a rich source of metabolites with well-known antibacterial properties. The present study aimed to investigate the antibacterial activity of symbiotic (n = 1) and non-symbiotic (n = 8) entomopathogenic bacterial species associated with the entomopathogenic nematode (EPN) Steinernema feltiae against four multidrug-resistant bacterial species. Bacterial cells and filtrates from Xenorhabdus bovienii strongly inhibited the growth of Staphylococcus aureus (33.3 and 28.9 mm) and Escherichia coli (24.6 and 21.6 mm) in disk diffusion, minimum inhibitory concentration (MIC) (2 and 8 µl/ml) and minimal bactericidal concentration (MBC) (4 and 12.5 µl/ml) assays. In conclusion, the direct application of endogenous S. feltiae-associated EPB, especially X. bovienii, appears promising as an antibacterial agent against multidrug-resistant bacteria (MRBs).