Abstract
The morphology, infection kinetics, genome sequence and phylogenetic characterization of the previously isolated bacteriophage vB_EcoD_SU57 are presented. The phage vB_EcoD_SU57 was isolated on Escherichia coli strain ECOR57 from the E. coli reference collection and was shown to produce four mm clear plaques with halos. Infection kinetics, as assessed by one-step growth analyses, suggest that vB_EcoD_SU57 is a virulent phage with an adsorption rate of 8.5 × 10–10 mL × min–1, a latency period of 14 min, and a burst size of 13 PFU per bacterium. Transmission electron microscopy confirmed vB_EcoD_SU57 to be a phage that used to be classified as a Siphoviridae phage. Bioinformatics analyses showed that the genome was 46,150 base pairs long, contained 29 genes with predicted protein functions, and 51 open reading frames encoding proteins with unknown function, many of which were gathered in clusters. A putative tRNA gene was also identified. Phylogenetic analyses showed that vB_EcoD_SU57 is a Braunvirinae phage of the newly formed Drexlerviridae family and closely related to T1-like E. coli phages vB_EcoS_ACG-M12 (Guelphvirus) and Rtp (Rtpvirus) as well as the unclassified phages vB_EcoS_CEB_EC3a and ECH1.
Highlights
T1-like phages have an icosahedral head of about 60 nm and a slender tail of about 150 nm, placing them in the newly formed family of tailed phages, Drexlerviridae, which consists of T1like phages from the Siphoviridae family (German et al, 2006; Adriaenssens et al, 2020)
The Drexlerviridae family consists of three additional subfamilies, holding many genera of T1like phages, all of which were isolated utilizing gammaproteobacteria as hosts (Niu et al, 2014; Adriaenssens et al, 2020)
The adsorption rate of phage T1 is around 3 × 10−9 mL × min−1, which is considered to be among the highest rates of phage adsorption, and the time from infection to lysis of the bacterium is short, 15–20 min (Drexler, 1988; German et al, 2006). These properties would prove advantageous for phage therapy as they theoretically lead to a fast elimination of an infecting bacteria, provided that the phage dose reaching the bacteria is high enough
Summary
T1-like phages have an icosahedral head of about 60 nm and a slender tail of about 150 nm, placing them in the newly formed family of tailed phages, Drexlerviridae, which consists of T1like phages from the Siphoviridae family (German et al, 2006; Adriaenssens et al, 2020). Many more relatives to T1 have been isolated and their genome sequenced, and it appears as if close relatives to phage T1 are only to be found to infect E. coli and Shigella species Phages of this coherent group are classified into the genus Tunavirus, and together with other related T1-like phages classified into two other genera into the subfamily Tunavirinae. The adsorption rate of phage T1 is around 3 × 10−9 mL × min−1, which is considered to be among the highest rates of phage adsorption, and the time from infection to lysis of the bacterium is short, 15–20 min (Drexler, 1988; German et al, 2006) These properties would prove advantageous for phage therapy as they theoretically lead to a fast elimination of an infecting bacteria, provided that the phage dose reaching the bacteria is high enough. SU57 has been characterized based on its morphology, infection biology kinetics, genomic composition, and phylogenetic relatedness to other phages
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