Characterization of a carbon source-dependent, phytohormone-responsive, free methionine-(R)-sulfoxide reductase from Komagataeibacter hansenii

Abstract

Komagataeibacter hansenii ATCC 23769 is a gram negative, non-pathogenic, acetic acid bacterium, best known for its ability to produce bacterial cellulose (BC). BC, an extracellular polysaccharide, is an important component of biofilms as it promotes anchoring to surfaces for nutrient acquisition and protection from environmental stress. BC has been long studied however, there is a lack of research pertaining to the regulation of BC production. In this thesis, the functional role of a putative free methionine sulfoxide reductase (MsrC) was characterized using a knockout mutant. The growth of the mutant was greatly affected by the presence of ethylene, abscisic acid and indole-3-acetic acid while oxidative stress increased BC production. Fructose-grown cultures produced more reactive oxygen species than in glucose. Oxidative stress upregulated genes involved with survival, growth, cellulose production, and stress defense. Therefore, MsrC is both phytohormone and oxidative stress responsive, coordinating cellular functions such as growth and BC production.