I learned in my food microbiology class that Streptococcus thermophilus and Lactobacillus bulgaricus precipitate the curd of swiss cheese. However, I was wondering what type of mechanisms do these bacteria use in order to accomplish this process.
lactic acid bacteria ferment the disaccharide lactose present in high amounts in milk to the three-carbon compound lactic acid, which acidifies the milk. this causes the proteins also present in milk to denaturate and coagulate, forming curdles. other causes/methods of curdling can be application of heat, salts or by adding the enzyme chymosin (rennin).