Comparison of stress adaptation and survival rate between Burkholderia pseudomallei with mutant and wild type bfmR.

Burkholderia pseudomallei (Bp) is highly adaptable to a wide range of environmental changes for survival and pathogenesis. However, the underlying mechanisms of such adaptability are still unclear. Two-component system (TCS) is a common signal transduction used by bacteria in response to environmental changes. A gene designated as bfmR (locus tag of BPSL2024) has been proposed to encode a response regulator, a member of the TCS, and was studied by mutagenesis and comparison of its phenotypic changes compared with those of the wild type. The growth rates of the mutant Bp at temperatures of 37 degrees-39 degrees C and pH 5-8 were significantly lower than the wild type strain (p < 0.05), especially at 39 degrees C (p = 0.01) and pH 7 (p = 0.01). The survival rate of the mice infected with the mutant strain is not significantly different from mice infected with wild type strain. The defective phenotypes were recovered in the complemented strain. These results indicated that bfmR is involved in adaptation of Bp to thermal- and pH-induced stress conditions.