Carbon dioxide tends to penetrate bacterial cell membranes and influence bacterial cell growth by acidification of the interior of bacterial cells, displacement of oxygen and interference with cellular enzymes. The objective was to study the influence of carbonation on microbial and physicochemical characteristics of a fermented carbonated dairy beverage. Pasteurized milk was tempered to 32°C and inoculated with Lactococcus lactis. Inoculated milk was poured into bottles and incubated at 32°C until pH 4.6. Coagulum was broken by agitation. Coagulum was plain or flavored with blueberry puree. Carbon dioxide was incorporated at 0 (control) and 40 psi and products were stored at 4°C. Product was tested weekly over 3 wk for Lactococcus lactis, coliform and yeast and mold counts, pH, titratable acidity and carbon dioxide content. Entire experiment was replicated 3 times. On d 1 of manufacture, the Lactococcus lactis counts in all 4 products were steady at 6 logs. At 3 wk of storage, the Lactococcus lactis counts in the carbonated products were one log lower than their non-carbonated counterparts. Lactococcus lactis counts in the plain product with no carbonation was the highest while the counts in flavored product carbonated at 40 psi was the lowest at 3 wk. All products had no detectable coliform and yeast and mold counts over the 3 wk. Volume of dissolved carbon dioxide in the plain and flavored carbonated products held steady over the 3 wk of storage at 4.3 g/L. Combination of carbonation and flavoring lowered Lactococcus lactis counts at 3 wk in the carbonated drinkable cheese product.