INDIRECT CONDUCTANCE FOR MEASUREMENTS OF CARBON-DIOXIDE PRODUCED BY STREPTOCOCCUS-SALIVARIUS SSP THERMOPHILUS TJ-160 IN PURE AND MIXED CULTURES

The CO2 produced by Streptococcus salivarius ssp. thermophilus TJ 160 during urea hydrolysis was estimated using indirect conductance measur ements in pure culture and in mixed cultures with Lactobacillus. To qu antify the concentration and rate of CO2 production, conductance measu rements were converted to CO2 values; -240 muS corresponded to 1 mumol of CO2 at 37-degrees-C. The estimation of CO2 produced by S. salivari us ssp. thermophilus in reconstituted skim milk was related to the amo unts of urea degraded in pure and mixed cultures. Lactobacillus delbru eckii ssp. bulgaricus and Lactobacillus acidophilus did not consume ur ea or produce CO2. Part of the CO2 produced by S. salivarius ssp. ther mophilus disappeared during growth in mixed cultures with Lactobacillu s.