Characterization of exopolymeric substances (EPS) produced by Aeromonas hydrophila under reducing conditions

Abstract

The aim of this work was to investigate the production of extracellular polymeric substances (EPS) by Aeromonas hydrophila grown under anaerobic conditions. EPS composition was studied for planktonic cells, cells attached to carbon fibre supports using a soluble ferric iron source and cells grown with a solid ferric iron mineral (gossan). Conventional spectrophotometric methods, Fourier transform infrared (FTIR) and confocal laser scanning microscopy (CLSM) were used to determine the main components in the biofilm extracted from the cultures. The key EPS components were proteins, indicating their importance for electron transfer reactions. Carbohydrates were observed mostly on the mineral and contained terminal mannosyl and/or terminal glucose, fucose and N-acetylgalactosamine residues.

Keywords:

• Aeromonas hydrophila
• extracellular polymeric substances
• CLSM
• FTIR
• SEM

Acknowledgements

The authors are grateful for the financial support given by the Spanish Ministry of Economy and Competitiveness to fund this work (project MAT2011-24186, for L. Castro’s fellowship BES-2009-021700), and for the CSC funding (R. Zhangs's fellowship). They also thank José E. Fernández from CAI Espectroscopía (Unidad Infrarrojo-Raman-Correlador) of Complutense University of Madrid, Spain.