please read the Benson\'s Microbiological Applications laboratory Manual 14th ed

Question

please read the Benson's Microbiological Applications laboratory Manual 14th edition

Prelab #8 Exercise 57 - Bacterial Counts on food (10pts) Read pages 381-385 of your lab manual and answer the following questions 1. What are three examples of foods that h 1.5pts) ve 2. What are two post-production treatments that reduce the number of microorganisms present in thes foods? (1pt) 3. The chalky appearance of grapes is due to the presence of..(1pt) 4. What are two microbes that are introduced into milk during milking and processing? (1pt) 5. Why can milk become sour due to bacteria even though it has been pasteurized? (1pt) 6. What method is used to ascertain if food is contaminated with fecal bacteria? (1pt) 7. In a standard plate count, how do you calculate the number of organisms per ml (1pt) 8. Where could the following bacteria be found - match using A, B, C, D, or E (2.5pts) e Clostridium botulinum o Staphylococcus aureus o Salmonella o Campylobacter o E.coli A. Home-canned foods B. Poultry and esgs C. Cattle meat D. Human hands E Animal intestines

Explanation / Answer

What are the three examples of foods that have high counts of microorganisms?

Ans 1) – The three most commonly found microbes in food are Pseudomonas, Moraxella and Bacillus species. Due to its growth favoring it is mostly involved in development of food spoilage.

Ans 2) The two post production treatment which helps in reducing number of food spoilage are use of food preservatives and irradiation. This helps in increasing the shelf life of the food by inactivating the microbial growth.

Ans 3) It is due to presence of large amount of anthocyanine pigments along with large amount of water content.

Ans 4) The most common microorganism species inserted during milking is Pseudomonas species and during processing Bacillus

Ans 5) The milk can become sour due to bacteria even after being pasteurized due to formation of lactic acid. The bacteria Lactobacillus grows and it leads to conversion of the lactose in milk to lactic acid.

Ans 6) The presence of fecal bacteria can be tested with the beta-glucuronidase assay. It is assayed by hydrolysis of enzyme and it leads to change in color.

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