Abstract
Bacterial biofilms adapt and shape their structure in response to varied environmental conditions. A statistical methodology was adopted in this study to empirically investigate the influence of nutrients on biofilm structural parameters deduced from confocal scanning laser microscope images of Paracoccus sp.W1b, a denitrifying bacterium. High concentrations of succinate, Mg++, Ca++, and Mn++ were shown to enhance biofilm formation whereas higher concentration of iron decreased biofilm formation. Biofilm formed at high succinate was uneven with high surface to biovolume ratio. Higher Mg++ or Ca++ concentrations induced cohesion of biofilm cells, but contrasting biofilm architectures were detected. Biofilm with subpopulation of pillar-like protruding cells was distributed on a mosaic form of monolayer cells in medium with 10 mM Mg++. 10 mM Ca++ induced a dense confluent biofilm. Denitrification activity was significantly increased in the Mg++- and Ca++-induced biofilms. Chelator treatment of various biofilm ages indicated that divalent cations are important in the initial stages of biofilm formation.
Acknowledgements
The authors acknowledge Samata Sripada for image acquisition by confocal microscopy. This study was supported by Gujarat State Biotechnology Mission (GSBTM) grant (GSBTM/MD/Projects/1450/2004-05).