Quantification of Triphenyl-2H-tetrazoliumchloride Reduction Activity in Bacterial Cells

Abstract

This protocol describes the use of the 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) salt to evaluate the cell redox potential of rhizobia cells. The production of brightly colored and insoluble 1,3,5-Triphenyltetrazolium formazan arising from TTC reduction is irreversible and can be easily quantified using a spectrophotometer. This protocol allows the production of reproducible results in a relatively short time for <i>Sinorhizobium meliloti</i> 1021 cells grown both in exponential and stationary phases. The results here presented show that the <i>S. meliloti</i> cells deriving from exponential-phase cultures had increased cell redox potential as compared to the ones deriving from stationary-phase cultures. This means that under exponential growth conditions the <i>S. meliloti</i> cells generate higher amount of reducing equivalents needed for TTC reduction.