Junior biologists may not realize how much we benefit from bacteria. Here is a reading passage that tells of how Lactobacilli are of use to humans. Readers find that a byproduct of Lactobacillii respiration is lactic acid, a compound that amazingly inhibits the growth of other bacteria that spoil food. These microorganisms are used to produce the sour taste in buttermilk, sour cream, and other food products. Two critical-thinking questions follow the reading passage. Use this assignment as an enrichment to your lessons on bacteria.