EZ TEST. EZTests are self-contained BIs that contain bacterial spores on a stainless steel disc, packaged within a small, thermoplastic culture tube with a sealed-glass media ampoule, specially-formulated soybean casein digest culture medium containing a color indicator, which turns a dramatic yellow when spores grow. Visual results within 24 hours (H2O2). ATCC Number: 7953. Packaging 100/box. EZ Test. SCBI G. stearothermophilus. Population: 10 log 6.