Free methionine sulfoxide reductase and its contributions to environmental stress response in Komagataeibacter hansenii

Abstract

Komagataeibacter hansenii (ATCC 23769) is a non-virulent acetic acid bacterium that forms cellulosic biofilms at the air-liquid interface of liquid media, serving as a model for biofilm forming pathogenic bacteria. In this thesis, the role of free methionine-R-sulfoxide reductase (MsrC) was investigated through comparative analysis of the wildtype (WT) K. hansenii, an msrC-deficient mutant (ΔmsrC), and a complemented strain using the shuttle plasmid pUCD2. The ΔmsrC mutation greatly affects growth, bacterial cellulose synthesis, abscisic acid response, quorum sensing and variability of cell size. Complementation restored some WT characteristics but revealed new phenotypes linked to bacterial cellulose synthesis. The tolerance to reactive oxygen species (ROS) was notably reduced in the absence of a functional MsrC. Additionally, the pUCD2 vector impacted pH and ROS tolerance. These findings highlight the multifaceted contribution of MsrC to bacterial physiology and biofilm dynamics, advancing our knowledge of its potential as a target for biofilm-related studies.