Microorganisms arc important in the production of many food related products. Fi
ID: 87507 • Letter: M
Question
Microorganisms arc important in the production of many food related products. Fill in the table below with 4 examples of microorganisms important in foods that you enjoy. Mention the correct phenotypic characteristics of the following mold species. There is an outbreak of Staphylococcus aureus food poisoning in the Salem, OR area. A common factor in all the hospital cases is that people affected with symptoms said they had eaten at the Popeyes Louisiana kitchen and that all of them had ordered the coleslaw with their delicious chicken meals. What techniques and procedures learned in class could you use to determine if there is S. aureus contaminating the coleslaw? Three different workers were responsible for preparing the coleslaw during business hours. Jill prepared the coleslaw in the morning, Steve prepared the coleslaw in the afternoon and Jack made the coleslaw in the evening. Using the information below, A) Calculate the Staph CFU/gram of coleslaw for each sample, B) determine who might have contaminated the coleslaw. 1 gram of coleslaw was used from each sample. Origin of contamination: Bonus: A bioengineer is running fermentation experiments to produce a new biofuel. The biofuel is produced as a byproduct of normal metabolism of lactose by a newly identified fecal coliform bacterial species. Currently the yield of biofuel is half the expected amount. The engineer suspects that there may be another bacterial species contaminating the recent fermentation. Use the information below to answer the following: Design an experiment using only what we have learned in class to determine A) If there is another bacterial species contaminating the fermentation and B) how to determine if the contaminating bacterium is affecting the biofuel yield.Explanation / Answer
1.
2.
3.
Part 1
Techniques and procedures for Coleslaw contamination by Staphylococcus aureus are
a.) Direct plate count method - it is used when the suspected sample is expected to be highly contaminated with Staphylococcus aureus cells.
b.) Most probable number method - it is used when the suspected sample is expected to be less contaminated with Staphylococcus aureus cells.
c.) other techniques for specific identification are coagulase test and latex agglutination test.
Part 2
a.)
cfu/gram = (no. of colonies x dilution factor ) / amount of culture plate
b.)
the coleslaw that was prepared by steve in the afternoon was contaminated with the rate of 2.3x107 Staphylococcus aureus cells per gram of coleslaw.
origin of contamination : steve
Bonus:
a.)experiment to determine another bacterial species that contaminating the fermentation is Eosin Methylene Blue (EMB) plate analysis.
b.) we can determine if the contaminating bacterium is affecting the biofuel yield by observing the gas production during the lactose fermintation of bacterial metabolism.
Microorganism Type of Microorganism Food or Beverage Lactobacillus acidipiscis Bacteria yogurt Mucor racemosus Fungus Cheese Penicillium chrysogenum Fungus Cheese Streptococcus thermophilus Bacteria Cheese or yogurt