Effect of starvation on the adhesive properties of xenobiotic degrading bacteria

The purpose of this study was to observe the effects of different starvation conditions on the surface characteristics and adhesive properties of bacteria. Three pure culture xenobiotic degrading bacteria were used in this study: Pseudomonas sp. strain A, Pseudomonas sp. strain D and Rhodococcus corallinus strain 11. These microorganisms were selected for to their ability to degrade cyanuric acid, which is a derivative of s-Triazine, a common herbicide. These microorganisms were separately starved for carbon (glucose) and nitrogen (cyanuric acid) and their physiological responses to starvation were measured. Results indicated that there was a remarkable shrinkage in size of Pseudomonas strain A starved for carbon for 16 days. The surface properties of these three microorganisms changed significantly on starvation. Surface hydrophobicities for all the microorganisms stayed more or less constant during carbon starvation conditions, whereas, there was a significant decrease in hydrophobicity when all three cultures were starved for nitrogen. In parallel to these findings, it was observed that when the hydrophobicity of the cultures decreased, the attachment capabilities of these microorganisms decreased. This is believed to be due to the production of highly hydrated extracellular polysaccharides when carbon is present in the medium. Results of this study have important implications on the transport and attachment of microorganisms during soil remediation processes. (C) 2002 Elsevier Science Ltd. All rights reserved.