The influence of single and combined effects of Zn, Cu and temperature on microbial growth

The purpose of the present study is to investigate the single and joint effect of zinc and copper to the growth pattern of the metal tolerant species of Arthrobacter sp. JM018. The results showed that, both, Zn and Cu at concentrations between 1 to 10 μM stimulated the growth of the above microorganism at 35 °C. Stimulation was reduced with the increase of Zn concentration, while the opposite phenomenon was observed for copper. On the other hand, similar concentrations of joint Zn and Cu resulted to slight growth inhibition, indicating antagonism between the studied heavy metals. Experiments with the same microorganism at 20 °C and 35 °C, at metal free and 10 μM Zn, indicated that the stimulatory effect of zinc was significantly more pronounced at lower temperatures. The latter is indicative of the strong role of temperature on the expression of heavy metals to microorganisms.