Isolation and Genomic Characterization of Selective Lytic Pseudomonas phage Amjad_SA from a Desert Urban Pond in Riyadh

Amjad N. Alotaibi^1,2Fahad H. Alqahtani^2,3Haila M. Alnassar¹Abeer H. Alomair¹Munirah S. Aleyiydi¹Ahmed M. Aldossary⁴Fahhad D. Alsahli⁴Abdulmalek T. Algarni⁴Sarah H. Algahtani¹Albatul A. Alshehri¹Maha I. Alturki¹Fahad M. Alhoshani¹Yaser A. Butt⁵Nojoud M. ALfayez¹Essam A. Tawfik¹Majed S Nassar^1*

• ¹Advanced Diagnostic and Therapeutic Institute, Health Sector, King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia
• ²$ Equal Contribution, Riyadh, Saudi Arabia
• ³Institute of Advanced Agricultural and Food Technologies, Sustainability and Environment Sector, King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia
• ⁴Wellness and Preventive Medicine Institute, Health Sector, King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia
• ⁵JOEL Asia Pte Ltd, Singapore, Singapore

Bacteriophages are abundant and diverse components of aquatic ecosystems and play a central role in shaping bacterial population dynamics and microbial diversity. Here, we report the isolation and characterization of Pseudomonas phage Amjad_SA, a lytic bacteriophage infecting a Pseudomonas isolate assigned to the Pseudomonas alcaligenes group (isolate 4L), obtained from an urban artificial pond in Riyadh, Saudi Arabia, located within an arid climatic region. Phage Amjad_SA exhibited lytic activity against the host isolate and did not infect other tested Gram-negative or Gram-positive bacterial species. Transmission electron microscopy revealed a tailed double-stranded DNA bacteriophage with an icosahedral head (47.5 ± 1.2 nm) and contractile tail (69.7 ± 1.1 nm), consistent with members of the class Caudoviricetes. Under the experimental conditions tested, the phage retained infectivity following incubation at temperatures between 25°C and 65°C and across a pH range of 5 to 9. Genomic analysis showed that Amjad_SA possesses a linear double-stranded DNA genome of 45,788 bp with a GC content of 60.4%, encoding 72 predicted open reading frames. Functionally annotated genes included proteins involved in genome replication, packaging, host lysis, and virion structure, while a substantial proportion of open reading frames encoded hypothetical proteins, reflecting current limitations in bacteriophage genome annotations. A single tRNA gene, tRNA-Ser (aga), was identified, indicating reliance on host translational machinery. Collectively, these findings provide biological and genomic data for Pseudomonas-infecting tailed bacteriophage recovered from an urban aquatic environment within an arid region and contribute to the growing reference framework for bacteriophages associated with Pseudomonas species.