Effect of starvation on resuscitation and the surface characteristics of bacteria.

Resuscitation behavior of bacteria after starvation for carbon and nitrogen was investigated. In addition effect of carbon and nitrogen starvation conditions on the surface characteristics and adhesive properties of bacteria were studied. Two pure culture herbicide degrading bacteria were used in the study: Pseudomonas sp. strain A, and Rhodococcus corallinus strain 11. These bacteria are known to degrade cyanuric acid which is a derivative of s-triazine, a common herbicide used widely. Selected bacteria were starved for carbon (glucose) and nitrogen (cyanuric acid) in different bioreactors and their physiological responses to starvation and resuscitation were measured. Different resuscitation responses were observed under different starvation conditions such that long lag phase was, observed for Rhodococcus corallinus strain 11 subjected to cyanuric acid starvation. Slow exponential growth rates were calculated for both microorganisms subjected to cyanuric acid starvation. The surface properties of both microorganisms were investigated using MATH test with two different hydrocarbons (hexadecane and octane). Hexadecane was observed to be the best organic attachment phase for these tests. Surface hydrophobiciy for all the microorganisms stayed unchanged during carbon starvation conditions. Significant decrease in hydrophobicity was observed for both cultures starved for nitrogen. When the hydrophobicity of the cultures decreased, the attachment capabilities of the microorganisms decreased. The decrease in attachment capabilities is a result of highly hydrated extracellular polysaccharides produced in the presence of carbon in the medium. Results of this study can be used as control tools in soil remediation applications.