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T-even bacteriophages are known to employ lysis inhibition (LIN), where the lysis of an infected host is delayed in response to secondary adsorptions. Upon the eventual burst of the host, significantly more phage progenies are released. Here, we analysed the competitive advantage of LIN using a mathematical model. In batch culture, LIN provides a bigger phage yield at the end of the growth where all the hosts are infected due to an exceeding number of phage particles and, in addition, gives a competitive advantage against LIN mutants with rapid lysis by letting them adsorb to already infected hosts in the LIN state. By simulating plaque formation in a spatially structured environment, we show that, while LIN phages will produce a smaller zone of clearance, the area over which the phages spread is actually comparable to those without LIN. The analysis suggests that LIN induced by secondary adsorption is favourable in terms of competition, both in spatially homogeneous and inhomogeneous environments., Competing Interests: The authors have declared that no competing interests exists., (Copyright: © 2024 Hvid, Mitarai. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

As antimicrobial resistance (AMR) continues to increase, the therapeutic use of phages has re-emerged as an attractive alternative. However, knowledge of phage resistance development and bacterium-phage interaction complexity are still not fully interpreted. In this study, two lytic T4-like and T7-like phage infecting model Escherichia coli strain C600 are selected, and host genetic determinants involved in phage susceptibility and resistance are also identified using TraDIS strategy. Isolation and identification of the lytic T7-like show that though it belongs to the phage T7 family, genes encoding replication and transcription protein exhibit high differences. The TraDIS results identify a huge number of previously unidentified genes involved in phage infection, and a subset (six in susceptibility and nine in resistance) are shared under pressure of the two kinds of lytic phage. Susceptible gene wbbL has the highest value and implies the important role in phage susceptibility. Importantly, two susceptible genes QseE (QseE/QseF) and RstB (RstB/RstA), encoding the similar two-component system sensor histidine kinase (HKs), also identified. Conversely and strangely, outer membrane protein gene ompW, unlike the gene ompC encoding receptor protein of T4 phage, was shown to provide phage resistance. Overall, this study exploited a genome-wide fitness assay to uncover susceptibility and resistant genes, even the shared genes, important for the E. coli strain of both most popular high lytic T4-like and T7-like phages. This knowledge of the genetic determinants can be further used to analysis the behind function signatures to screen the potential agents to aid phage killing of MDR pathogens, which will greatly be valuable in improving the phage therapy outcome in fighting with microbial resistance., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)