# In Vitro Ferrophilic Responses of Photobacterium damselae subsp. piscicida EKL1 and Characterization of the Fe(III)-Piscibactin Complex

## TL;DR

This study explores how iron affects the growth and biofilm formation of a fish pathogen and suggests iron chelation as a potential treatment.

## Contribution

The study characterizes the Fe(III)-piscibactin complex and demonstrates the anti-biofilm potential of deferoxamine against Pdp.

## Key findings

- Iron limitation suppressed biofilm formation and planktonic growth in Pdp strain EKL1.
- Deferoxamine inhibited EKL1 biofilm production by 82.1%.
- The Fe(III)-piscibactin complex was characterized using spectroscopic analyses.

## Abstract

The Gram-negative marine bacterium Photobacterium damselae subsp. piscicida (Pdp) is a pathogen responsible for pseudotuberculosis in various fish species, posing significant threats to aquaculture. Pdp employs strong virulence mechanisms, one of which is the production of the piscibactin siderophore, which plays a key role in iron acquisition from the host. In this study, we evaluated the ferrophilic properties of the Pdp strain EKL1 in relation to growth and biofilm production. In vitro iron limitation significantly suppressed biofilm formation and planktonic growth in EKL1. We then investigated the anti-biofilm activity of deferoxamine (DFO), an iron chelator used to treat transfusion-induced iron overload in thalassemia patients, against EKL1. DFO strongly inhibited EKL1 biofilm production (by 82.1%), suggesting that iron chelation therapy could be an effective strategy to prevent Pdp-induced photobacteriosis outbreaks. Finally, we characterized the iron-bound form of piscibactin through extensive spectroscopic analyses of the siderophore produced by EKL1. Our findings contribute to the development of novel piscibactin-targeted inhibitors, advancing siderophore-based anti-virulence strategies against Pdp.