The study of time-course toxic impact of Ni on the thermostability of the soil Arthrobacter oxydans bacterial cell culture

Abstract

Abstract The study aims to analyze the time-dependent development of Ni toxic effect on the bacterial cell culture of Arthrobacter oxydans , supposed to have high potential for heavy metals detoxification. The differential scanning calorimetry (DSC) method was applied for the rapid assessment of toxic impacts on bacterial cells on the basis of the changes of their thermostability. The total melting specific heat of bacterial cells altered in accordance with the growth phases of the culture. We propose to use the bacterial cell culture at the stationary growth phase, characterized by high reproducibility of the melting profile, for rapid and correct detection of the toxic effect. The implementation of the differential scanning calorimetry method to the study of Ni toxic effect demonstrated the concentration and time-dependent development of cell stress response and detected the early initial changes of the thermograms, especially in the temperature region of DNA-protein melting. The major changes of the thermograms have been developed during the first two hour of Ni administration to the growth medium, possibly reflecting the stress-response alterations in gene expression and protein activity. The classical viability assays were not able to determine the toxic effect for the studied bacterial cells at that time point. The similar character of the metal toxic impact on the thermostability of the Staphylococcus epidermidis cell culture had been detected as well, despite the different general melting profile. The obtained data contribute to a better understanding of bacteria-metal interaction and could be applied to the bacteria stress-response studies.