I've Got Enough Milk! Leave Me Alone!

Overview

Objectives/Goals My project was to determine if pasteurized supermarket milk is free of any bacterial contamination and also whether milk that cames from cows treated woth rBST or milk free of rBST will increase bacterial growth. Methods/Materials 6 different brands of commercially available supermarket milk was tested for any bacterial contamination. Milk samples were incubated in nutrient broth and subcultures in nutrient agar plates capale of growing Gram positive and Gram negative bacteria. E. Coli and Strep. Viridans were grown in milk and bacterial colony count was done using a nephelometer. Results Ross and Valutime milk with rBST had the highest amount of bacterial growth, 5188.89 colony count/mL and 5000.00 colony count/mL respectively. Knudsen and and Stater Bros had 2222.22 colony count/mL and 4444.44 colony count/ml respectively. Full Circle had 555.56 colony count/mL and Horizon had no growth. Bacterial growth was less in organic milk. E. Coli and Strep. Viridans were grown in four brands of milk. Valutime and Ross had the highest amountof growth, and they both had 3333.33 colony count/mL. The brands Full Circle and Horizon did not have rBST and both had 1477.77 colony count/ mL Conclusions/Discussion My conclusion is that organic milk that is not from cows treated with rBST is relatively safe to drink for all age groups..

Competition history

• CSEF 2009 Microbiology · Entry J1728

Resources

• CSEF project summary ↗

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