G. stearothermophilus exponential phase vegetative cells were
grown in TSB at 45 C for 48 h before they were used for inoculation of food and drink samples. In order to obtain endospore
preparations, G. stearothermophilus cultures were grown in TSA
for approximately 10–15 days at 45 C. The level of sporulation
was monitored by staining the spores with a solution of 5%
malachite green and then with 0.5% safranin followed by