Defense Date

12-3-2025

Document Type

Thesis

Degree Type

Master of Science

Degree Name

Biological Sciences

First Advisor

Julie Torruellas Garcia, Ph.D

Second Advisor

Aurelien Tartar, Ph.D

Third Advisor

Jose Victor Lopez, Ph.D

Keywords

Antimicrobial resistance (AMR), bacteriophage therapy, Cluster DV, genome annotation, Gordonia rubripertincta, lysis kinetics, lysogenic, lytic, phage-host infection, synteny

Abstract

Antimicrobial resistance (AMR) is a global crisis, with 1 in 6 bacterial infections being resistant to antibiotics and causing 40 million deaths between 1990 and 2021 worldwide. This threat has resulted in the demand for alternative therapies, like bacteriophage therapy which uses viruses to treat bacterial infections by killing them. Gordonia rubripertincta is a gram-positive bacterium that is found in various habitats: water, soil, and on the exterior of plants. Gordonia species are rare, however, they are emerging as opportunistic human pathogens that may cause various infections in any individual. G. rubripertincta infections occur from surgical complications with a catheter or a heater-cooler device in a heart-lung machine. G. rubripertincta infections are difficult to treat due to limited knowledge of its antibiotic susceptibility and the increasing reports of infection in immunocompromised individuals. Despite this, a very few Gordonia rubripertincta bacteriophages have been characterized. We hypothesized that three novel G. rubripertincta bacteriophages (Jamemuya19, Alephilan, Mima20) exhibit conserved genomic synteny while maintaining biological infection dynamics that influence their potential for therapeutic applications. Cryo-electron microscopy confirmed siphoviridae morphology with long, non-contractile tails. Through the use of bioinformatic tools, each genome was annotated and identified 92-98 protein coding genes with genome lengths of 65-68 kb and GC content of 58%. All three bacteriophages showed strong synteny, having more than 88% of shared gene content similarity which helped to classify them into Cluster DV. The lack of lysogenic genes and the presence of lytic genes suggest the phages undergo a lytic life cycle. No lysogens or spontaneous phage release were detected which further suggests all three bacteriophages follow a lytic life cycle. After infection with each phage, G. rubripertincta did not undergo spontaneous phage release which further suggests the phage undergo the lytic lifecycle. Temperature-dependent phage infection assays showed successful infections at 25°C, 30°C, 37°C, and 40°C with optimal infection temperature of 30. Lysis kinetics assays revealed that the phage remain infective at very low concentrations of phage with the lysis times being faster at 37°C than at 30°C. Altogether, these findings expand on the current understanding of Cluster DV phage evolution and genomic synteny. Despite their conserved genomic architecture, these phages exhibit diversity in lysis kinetics. Collectively, these characteristics identify Jamemuya19, Alephilan, and Mima20 as strong candidates for future phage therapy or biotechnological applications that target G. rubripertincta.

Download
Share Feedback

Share

COinS