The organisms were studied in batch cultures and the maximum specific growth rate (~a~) was determined in air, 5% CO2 + nitrogen and 100% CO2; from which the relative inhibitory effect of COs was estimated for each organism. Using 100% CO2 reduced the growth rate for all test organisms. Compared to growth in air, the relative inhibitory effect of 100% CO2 was highest for Bac. cereus, Br. thermosphacta and A. hydrophila (> 75%), and lowest for E. coli, Str. faecalis and the Lactobacillus spp. (53%-29%). Compared to anaerobic growth, the relative inhibitory effect of 100% CO2 was generally somewhat lower and the succession of COs-resistance was slightly altered for some organisms but drastically increased for Br. thermosphacta. The relative inhibitory effect was highest on Bac. cereus, A. hydrophila and Y. frederiksenii (67%-52%) and lowest on Y. enterocolitica, Br. thermosphacta and the Lactobacillus spp. (26%-8%). The anaerobic growth in nitrogen was generally slower than the aerobic growth. The exceptions were Streptococcus faecalis (only 2% reduction) and Clostridium sporogenes (no aerobic growth). In 100% COs Str. faecalis, Citrobacter freundii and Escherichia coli had highest /Ama x and Brochothrix therrnosphacta, Bacillius cereus and Staphylococcus aureus the lowest.