Characterization of Pseudomonas aeruginosa Infecting Bacteriophages from Swiftlet House Pond Water and Sewage in South Kalimantan, Indonesia

Pseudomonas aeruginosa is an opportunistic bacterium that may occur in animal-production environments and contribute to microbial contamination of animal-derived products. However, information on P. aeruginosa-infecting bacteriophages in artificial swiftlet-house environments remains limited. This study aimed to isolate and evaluate P. aeruginosa-infecting bacteriophages from the swiftlet-house environment in South Kalimantan, Indonesia. A total of 75 samples involving pond waters (n = 25), sewages (n = 25), and soil (n = 25) were obtained from four artificial swiftlet houses and screened for bacteriophage activity against P. aeruginosa FKH-AP (GenBank accession no. PZ351230), Acinetobacter bereziniae TK8 (PX000546.1), Shigella flexneri FB3 (PZ384610), Escherichia coli TJ9 (PZ384611), and Klebsiella pneumoniae TB4 (PZ384612), using spot tests and plaque assays. The bacteriophages were purified through three successive rounds of plaque purification. Plaque morphology and phage titer were evaluated using plaque assays, and virion morphology was examined using Transmission Electron Microscopy (TEM). Two of 75 environmental samples, designated AC2 (pond water) and FC2 (sewage), showed phage activity against P. aeruginosa FKH-AP, with initial titers of 5.1x10⁷ PFU/mL and 4.1x10⁷ PFU/mL, respectively. After purification, phage AC2 and FC2 reached titers of 1.2x10¹⁰ PFU/mL 1.8x10¹². Based on the morphology test, phage AC2 produced small and clear plaques, while phage FC2 produced large and clear plaques. Further, TEM revealed virions with icosahedral capsids and elongated contractile tails, consistent with Myoviridae. This study provides evidence of P. aeruginosa-infecting bacteriophage activity from pond water and sewage associated with artificial swiftlet houses in South Kalimantan, Indonesia.