Microbiology
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Microbiology in Health and Disease
SAMPLE (2)
Fecal contamination in fresh products from supermarket in Brooklyn
The purpose of the Research in the Classroom (RIC) project was to apply set of skills and techniques received during Microbiology class. This project created to identify pathogenic bacteria that is responsible for foodborne illnesses. Food borne illnesses are caused by consuming food contaminated with prions, pathogenic, bacteria, toxin, viruses or parasites. Three major species of the Enterobacteriaceae family: Escherichia coli (E-Coli), Salmonella sp are associated with the periodic outbreak of food-related infection.
For the Research in the Classroom three food samples were purchased in Stop and Shop supermarket located in the 1710 Avenue Y, Brooklyn, NY 11235 on June 22, 2019. Sample # 1 was fresh fish. Sample # 2 was dill and sample # 3 was broccoli. All this sample were brought to microbiology class and placed to EE Broth, Mossel, selective enrichment media for Enterobacteriaceae species, incubated at 35-37º C at least for 18-24 hours. Typical EE Broth, Mossel, contains peptic digest of animal tissue (10g/L), dextrose (5g/L), disodium phosphate (6.45 g/L), monopotassium phosphate (2 g/L), Ox bile, purified (20g/L), Brilliant green (0.0135g/L), final pH: 7.2± 0.2 at 25ºC. In the following lab session samples were inoculated to Nutrient Agar (NA) plate, MacConkey Agar plate, and Xylose Lysine Tergitol-4 (XLT) Agar plates using streak (fishtail) method explained in the lab manual. NA media typically contains peptone (5g/L), sodium chloride (5g/L), HM peptone B (1.5g/L), yeast extract (1.5g/L), agar (15g/L), final pH: 7.4±0.2 at 25ºC. MacConkey Agar media typically contains peptone (17g/L), proteose peptone (3g/L), lactose monohydrate (10g/L), bile salts (1.5g/L), sodium chloride (5g/L), neutral red (0.03g/L), crystal violet (0.001g/L), agar (13.5g/L), final pH: 7.1±0.2 at 25ºC. XLT-4 agar media typically contains lactose (7.5g/L), sucrose (7.5g/L), sodium thiosulfate (6.8g/L), sodium chloride (5g/L), xylose (3.75g/L), yeast extract (3g/L), proteose peptone (1.6g/L), ferric ammonium citrate (0.8g/L), phenol red (80g/L), tergitol 4 (4.6g/L), agar (18g/L), final pH: 7.4±0.2 at 25ºC.
Results: The pictures of MacConkey, NA and XLT-4 Agar plates with bacterial species obtained from three mentioned samples are presented in the Figure #1 and #2. (PLEASE JUST SKIP IT)
Escherichia coli is a bacterium found in lower GI tract of many animals. It can be harmless or cause from mild to serious infection disease. It is probably the best known of all the bacterium. It not only helps us with digestion, but also a source of some vitamins K and B as a result of its metabolism. People who take a lot of antibiotics may cause to significantly reduce the Escherichia coli in our intestine that will cause a digestive upset. Whenever it is present in food supplement it indicates that food was contaminated. As long as the bacteria does not get to other parts of the organ system it will not do any harms.
(SAMPLE)References:
https://academic.oup.com/fqs/article/1/4/289/4735151
https://www.cnn.com/2013/06/28/health/e-coli-outbreaks-fast-facts/index.html