Lactobacillus wasatchensis WDC04 causes late gas formation in Cheddar cheese by releasing CO₂ from a 6-carbon sugar when its preferred carbohydrate source, ribose, has been depleted. Growth curves were generated for WDC04 at pH 6.5, 5.2, and pH 5.2 with 3% NaCl added, using MRS-carbohydrate restricted (MRS-CR) medium containing 1% ribose. Lowering the pH and adding salt to simulate cheese conditions decreased the growth rate of WDC04. The ratio of ribose to galactose (R:G) was then varied. Aliquots of WDC04 were inoculated (n = 3) into pH 6 MRS-CR media containing 1% carbohydrate with R:G of 10:90, 20:80, 30:70, 40:60, 50:50 and 100:0, so 3 tubes for each R:G ratio initially contained 10¹, 10³, 10⁵ or 10⁷cfu/mL. Each tube contained a Durham tube for gas detection and the tubes were incubated at 30°C for 7 d. Gas was observed after 2 d in tubes with 30:70 R:G or higher, with as little as a 10³ cfu/mL inoculum. No gas was detected in 10:90 or 100:0 R:G tubes. As the ribose concentration was increased, gas appeared sooner for each inoculum level. Gas production appears dependent on (1) having ribose available to allow growth of WDC04 to high numbers followed by (2) having residual galactose that when used by WDC04 for energy production generates sufficient CO₂ to saturate the medium with excess gas being captured in the Durham tube. When grown at pH 5.2 with 3% NaCl, the growth rate of WDC04 was so reduced that no gas formation was observed even after 28 d. Interestingly, under these cheese-like conditions, when the control 100:0 R:G tubes reached a maximum growth to ~10⁹ cfu/mL, with further incubation there was a 2 log decrease in cell concentration (as shown by a drop in optical density). It then appeared that WDC04 was utilizing ribose released from dead lysed cells to go through a second growth phase. Risk factors for late gassing in cheese still appear dependent on the number of gas-forming lactobacilli present in the cheese, their ability to grow to high numbers using ribose from lysed starter culture cells, and being able to scavenge 6-carbon sugars present in the cheese after growth based on ribose has occurred.