The milk fermented with Lactobacillus acidophilus bacteria is not a kefir. Kefir is produced also by fermentation but using the different species of bacteria.
Lactobacillus acidophilus is a popular specie of probiotic bacteria used in almost every bacterial probiotics you can buy in a health food store.
Moreover it is used to produce many different fermented foods including the plain yogurt and fermented milk which are very popular foods in many countries in the world.
The two Petri dishes were filled with 4 ml of Lactobacillus acidophilus fermented cow’s milk (bought in a grocery store) and covered with the lid immediately.
The only difference in second Petri dish is that