Phage-induced bacterial morphological changes reveal a phage-derived antimicrobial affecting cell wall integrity

Area of Science:

• Microbiology
• Genomics
• Biochemistry

Background:

• The rise of antibiotic resistance necessitates the development of novel antimicrobial agents.
• Bacteriophages (phages) and their components are promising alternatives to traditional antibiotics.
• Identifying specific antimicrobial functions within phage genomes requires efficient screening methods.

Purpose of the Study:

• To explore phage-derived antimicrobials by analyzing phage-induced bacterial morphological changes.
• To identify and characterize a potential antimicrobial gene product from vibriophage KVP40.
• To validate the antibacterial activity of the identified phage gene product.

Main Methods:

• Infection of *Vibrio parahaemolyticus* with vibriophage KVP40 and observation of morphological changes.
• Genome analysis of KVP40 to identify potential cell wall-degrading enzymes.
• Heterologous expression of KVP40 lytic transglycosylase (LT) in bacteria for functional analysis.
• Single-cell morphological analysis and viability assays to assess antibacterial activity.

Main Results:

• Vibriophage KVP40 infection induced bacterial morphological changes similar to cell wall synthesis inhibitors.
• KVP40 genome analysis identified lytic transglycosylase (LT) as a candidate antimicrobial.
• Expression of wild-type KVP40-LT replicated the phage's antibacterial morphological effects, while truncated or mutant versions did not.
• The catalytic and signal peptide domains of KVP40-LT are crucial for its antibacterial activity.

Conclusions:

• Phage-induced morphological changes can serve as a valuable indicator for discovering novel phage-derived antimicrobials.
• KVP40-LT exhibits potent antibacterial activity, targeting bacterial cell wall synthesis.
• This study establishes a novel strategy for identifying and developing phage-based antimicrobials.