# Pseudomonas psychrophila Biofilm Formation Inhibition by Thymol Adaptation

## TL;DR

This study shows that exposing a Pseudomonas psychrophila strain to thymol reduces its ability to form biofilms and alters its metabolism.

## Contribution

The study reveals that thymol adaptation disrupts biofilm formation and affects redox and energy metabolism in a multidrug-resistant Pseudomonas strain.

## Key findings

- Thymol adaptation reduces biofilm formation, swarming motility, and rhamnolipid production in Pseudomonas psychrophila.
- Confocal microscopy shows TH-adapted strains form less structured biofilms.
- Metabolic analysis identifies 20 underexpressed metabolites linked to redox and energy balance.

## Abstract

This study investigated
the effects of thymol (TH) adaptation on
biofilm formation and the metabolic profile of the multiresistant
slaughterhouse isolate Pseudomonas psychrophila M33T02.2. After exposure to increasing sublethal concentrations
of thymol, the adapted P. psychrophila M33T02.2 showed decreased biofilm-forming capacity, reduced swarming
motility, and lower rhamnolipid production compared to the wild-type
strain. Confocal microscopy further showed that the biofilms developed
by the adapted strain were less homogeneous, confirming their inability
to develop well-structured biofilms. To further understand these changes
at the metabolic level, high-performance liquid chromatography (UHPLC-Orbitrap-MS/MS)
identified redox metabolism intermediates and energy balance-related
metabolites as most important variables. 20 metabolites were underexpressed
for the TH-adapted strain, including glutathione disulfide, guanosine
diphosphate, and flavin adenine mono- and di-nucleotide, among others.
Therefore, we conclude that repeated exposure to TH prevents the emergence
of resistance mechanisms associated with biofilm formation, acting
at the level of redox state and energy imbalance.