Microbial Growth of Bacteria

IN THIS EXPERIMENT YOU WILL…

Grow, isolation and identification fast growing bacteria known as ABC cultures found in yogurt. These bacteria species are responsible for the clotting and thickening of milk in yogurt.

This group of bacteria can grow in aerobic conditions (oxygen present) and rely on lactose to grow. Students will use 2 set of growth media (1 normal and 1 selective) so that they can determine which microorganism is the lactobacilli organism originating from the yogurt sample.

When classifying bacteria, microbiologists look at 3 properties:

• Peptidoglycan layer in surface membrane ( AKA gram negative or positive) and other structure characteristics
• Aerobic or anaerobic bacteria
• Sugars used as an energy source

The bacteria that will be grown are lactobacillus (lactose digesting bacteria that are rod shaped and can survive in aerobic conditions).