Role of EPS in mitigation of plant abiotic stress: the case of Methylobacterium extorquens PA1
Vanacore, A.; Forgione, M. C.; Cavasso, D.; Nguyen, H. N. A.; Molinaro, A.; Sáenz, J. P.; D’Errico, G.; Paduano, L.; Marchetti, R.; Silipo, A. (2022) Carbohydrate Polymers, 295, 119863. DOI: 10.1016/j.carbpol.2022.119863
Summary
This study characterized the exopolysaccharides (EPSs) secreted by [[methylobacterium-extorquens|Methylobacterium extorquens]] PA1 under standard growth conditions and methanol stress. The bacterium secretes a heterogeneous mixture of EPSs, and methanol exposure induces production of structurally distinct polymers with variable degrees of methylation. These structural differences influence the 3D conformation, supramolecular organization, diffusion properties, and hydrodynamic radius of the polymers, likely contributing to increased methanol tolerance and cell stability. No direct methanol involvement in the EPS solvation shell was detected, indicating that polymer exposure to methanol is water-mediated.
Key Findings
- M. extorquens PA1 secretes a heterogeneous mixture of EPSs that changes in composition under methanol stress
- Methanol-induced EPSs have different structures, repeating units, and variable degrees of methylation compared to reference conditions
- Structural differences influence 3D conformation, supramolecular assembly, and hydrodynamic properties
- EPS methylation degree correlates with altered physical properties that likely increase methanol tolerance
- Methanol does not directly interact with the EPS solvation shell — the polymer exposure is water-mediated
Our Contribution
Our group contributed expertise on [[methylobacterium-extorquens|M. extorquens]] biology and membrane stress responses, supporting the connection between EPS production and environmental stress tolerance.
Significance
This work extends understanding of how M. extorquens tolerates methanol beyond the well-characterized membrane lipid adaptations, showing that secreted exopolysaccharides provide an additional layer of protection against solvent stress.