you could describe the metabolic process of the bacteria that is used during cheese making, indicating the type of respiration that is happening during the process and the chemical reactions necessary for the formation of lactic acid.
Lactic acid is inoculated artificially by selected bacteria named as starters. Lactic acid formation is necessary in all kinds of cheese. For cheese prepared at temperature less than 40°C strains of Lactococcus lactis are used. For those prepared at higher temperatures the more thermophilic Streptococcus thermophilus, Lactobacillus bulgaricus, and Lact. helveticus are used.
C12H22O11 (lactose) + H2O (water) → 4 CH3CHOHCOOH (lactic acid)