E Coli Identification

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E. coli Identification in Ground Beef
Food microbial identification is a common study that involves isolating bacteria strain and determining its specific species. By doing so, researchers are able to conduct particular analysis on a single strain which pose negative effects towards human health, hence explore the solution to eliminate its contamination in food products. Generating from animal feces, E. coli is the most general bacteria that exists in various types of meats and their byproducts. Because the grinding process of ground beef will mince meat from different parts of cattle, ground beef possesses a fairly high possibility to be contaminated by E. coli. Some particular E. coli species in ground beef can cause lethal effects on the human body, therefore isolating and analyzing these species is crucial. To identify the E. coli species, ground beef samples will be prepared for experimentation through first culturing in general nutrient medium to render mass bacterial growth, then relocating the sample to selective medium to isolate E. coli. Lastly, the final bacterial strain can be determined by genetic sequence analysis via professional laboratory equipment. General culturing, as the first step of the procedure, will provide abundant nutrients for more than 90% of all microorganisms. The nutrients includes protein, carbohydrate and fat, thus the beef extracted peptone broth is chosen to be the ideal growth medium. When performing a microbial culture, it is important to carefully conduct sterilization beforehand or any potential microorganism from the environment is likely to contaminate the sample and affect the accuracy of experiment. The product of the first step will be then transferred to a selective medium called the Maconkey Plate, which would help particularly characterize E. coli strain. As illustrated in the Figure 1, the light pink dots typically represent the isolated E. coli colony according to the physical selectivity of the plate....
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