Insights on the Aeromonad Phages in Meycauayan-MarilaoObando River System (MMORS) based on Integrative Physiological and Gene-based Approach

Aeromonas hydrophila is a well-known fish pathogen that commonly infects aquaculture fishes.It is normally found in aquatic environments such as lakes, ponds, and sewage -with their growth more conducive in locations with high organic load.One identified location in the Philippines with high levels of pollution and anthropogenic waste input is the Marilao-Meycauayan-Obando River System (MMORS), a 52-kilometer river system located in the province of Bulacan (Luzon Is.).This study explored the presence of Aeromonas hydrophila phages and characterized the viruses through phenotypic and gene-based analysis.The natural existence of both A. hydrophila and their phages can have various implications and potential aquaculture applications.Six (6) phages were determined to have varying lytic abilities based on the nature of their isolation location and conferred stability due to their exposure to different pollutants such as fecal and organic waste, detergents, and heavy metals that can increase phage persistence.Additionally, extended marker-gene based analysis showed high sequence similarity between the isolated phages and were identified as Unclassified Biquartavirus, under Family Straboviridae, Order Pantevenvirales.Although limited in number, this initial description of phages from MMORS show that these locations can harbor ecologically diverse phages whose physiological and lytic characteristics can be attributed to pollution-driven variability -while highlighting the conservation of vital structural genes based on the marker gene analysis.These insights provide a foundation for advancing phage ecology research in Philippine freshwater environments and for exploring their potential applications in aquaculture and environmental health.