Abstract
The present study describes the role of a novel metallothionein in copper homeostasis in a newly discovered ciliate Tetrahymena farahensis. The ciliate showed optimum growth at 27 +/- 1 degrees C and pH 7.0 to 7.5. The maximum resistance dose of copper for T. farahensis was found to be 8, 9 and 80 mu g/ml in wheat grain medium, Bold-basal salt medium and modified Neff's medium, respectively. T. farahensis exhibited significant copper storage ability removing 54.9 % copper from medium within 96 h of 30 mu g/ml copper stress. The maximum uptake rate was observed within 30 min of copper administration in response to 5-100 mu g Cu++/ml in the medium. Quantitative analysis showed that TfCuMT is a copper inducible gene, the basal transcriptional level of which increased within 15 min of 10 mu g/ml copper exposure upto 87.3 folds that later on decreased. Accordingly, maximum uptake rate was observed between 15 to 30 min of copper exposure indicating possible role of TfCuMT as copper metallothionein. T. farahensis and TfCuMT can be used as biotechnological tools for bioremediation.