• Streptococcus lactis
• Streptococcus thermophilus
• Streptococcus faeca
• Lactobacillus bulgaricus
• Lactobacillus acidophilus
• Lactobacillus lactis
• Leuconostoc citrovorum
• Leuconostoc cremaris

One of the byproduct of sour milk is butter, by churning the sour milk or pasteurized milk; butter fat can be separated in to butter milk or skimmed milk respectively.

The flavor of cream or butter is also improved by inoculating cultures of Streptococcus lactis or Leuconostoc citrovorum.

Butter is detoriated or spoiled by some organisms including fungi like; Cladosporium and Penicillium