Activity and survival of tribromophenol-degrading bacteria in a contaminated desert soil

A strain of bromophenol degrading bacteria was isolated from a contaminated desert soil. The isolate identified as Achromobacter piechaudii and designated as strain TBPZ was able to metabolize both 2,4,6-tribromophenol and chlorophenols. The degradation of halophenols resulted in the stechiometric release of bromide or chloride. Growth and degradation of bromophenol were enhanced in the presence of yeast extract. To follow the survival of an introduced bacteria in the contaminated soil, TBPZ was transformed with a plasmid carrying a gene for kanamycin resistance and the lux CDABE operon from the luminescent bacteria Vibrio fischeri under the control of a constitutive promoter producing strain TBPZ-N61. The activity of the transformed bacteria was not affected by the insertion of the plasmid. Specific detection of the introduced isolate in the contaminated soil samples was achieved by selection on kanamycin. Survival of the introduced bacteria, TBPZ-N61, in the contaminated soil was influenced by soil moisture. Biodegradation of TBP occurred only in soil with at least 25% water content. Addition of yeast extract increased the survival and the activity of the introduced bacteria. The current study demonstrated that the limiting factors controlling pollutant degradation in a contaminated desert soil are water content, nutrient availability and the bioaugmentation of an appropriate microbial population.