ISSN: 0973-7510

E-ISSN: 2581-690X

Research Article | Open Access
Othman M. Alzahrani
Department of Biology, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia.
Article Number: 8396 | © The Author(s). 2023
J Pure Appl Microbiol. 2023;17(1):309-319.
Received: 11 January 2023 | Accepted: 21 January 2023 | Published online: 03 February 2023
Issue online: March 2023

Recently, the search for novel products derived from natural sources has become necessary due to the decreasing effectiveness of current antibiotics in treating bacteria that are antibiotic-resistant. In this context, it is well known that entomopathogenic bacteria (EPBs) produce a broad range of secondary metabolites with antibacterial activities. Therefore, an in-vitro trial was conducted to isolate and identify non-symbiotic bacteria associated with entomopathogenic nematodes, Steinernema spp. and evaluate the antibacterial activity against four antibiotic-resistant bacteria. Four bacterial isolates, i.e. Pseudomonas alcaligenes ST-1, Paenibacillus barcinonensis ST-2, Bacillus mojavensis ST-3, and Bacillus megaterium ST-4 were non-symbiotically isolated from the heamolymph of dead Steinernema-infected Galleria mellonella larvae and molecularly characterized. The bacterial cells and filtrates from P. alcaligenes ST-1 strongly inhibited the growth of Staphylococcus aureus through disk diffusion (43 mm), minimum inhibitory concentration (2.5 µL/mL), and minimal bactericidal concentration (5 µL/mL) assay. Conclusively, the direct application of endogenous Steinernema-associated EPB as an antibacterial agent for antibiotic-resistant bacteria looked promising.


Non-symbiotic Entomopathogenic Bacteria, Molecular Identification, Antibiotic-resistant Bacteria, Antibacterial Activity

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© The Author(s) 2023. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License which permits unrestricted use, sharing, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.