Abstract
Low-temperature adaptation and protection for environmental stresses were studied in the gram-negative soil bacterium Bradyrhizobium japonicum 61A101c. B. japonicum was more resistant to alcohol, $H_2O_2$, heat and freezing following a pretreatment at $4^{\circ}C$, resulting in approximately 10 to 1,000 folds increased survival compared to mid-exponential-phase cells grown at an optimal temperature at $28^{\circ}C$. This phenomena relate to the cold shock protein expressed when cells are exposed to a downshift in temperature. To confirm the presence of cold shock protein genes in B. japonicum, a PCR strategy was employed using a degenerate primer set, which successfully amplified a putative csp gene fragment. Sequence analysis of the PCR product(200bp) revealed csp-like sequences that were up to 96% identical to csp gene of S. typhimurium.
