Streak plate The streak plate was successful due to the growth of colonies in the media. The unknown microbe was separated in small individual colonies. The colonies are light yellow in color, irregular shape, and shiny in texture. The successful separation of individual colonies is the foundation for many tests that will be used for the identification of the unknown bacteria. Gram Stain Gram stain is a common technique used to distinguish between gram positive and gram negative. Gram positive bacteria will be carrying a purple color of the crystal violet stains; whereas, gram-negative bacteria carry a hot pink color of the counterstain safranin. According to the result, the unknown bacteria are bacilli in a single arrangement. Their sizes are estimated at 2 micrometers wide. The …show more content…
Since it was determined that the unknown bacteria is gram negative, it is the member of the Enterobacteriaceae. The test is successful because the media turned blue, which indicated that the bacteria is citrate positive because they're able to utilize citrate as their sole carbon source. They also able to convert the ammonium phosphate to ammonia and ammonium hydroxide, which then use to alkalinize the agar. At pH 7.5 or higher, the agar will turn blue. EMB coliform Eosin Methylene Blue Agar is a selective medium because it contains dyes eosin Y and methylene blue, which can inhibit the growth of Gram-positive organisms. Since the unknown bacteria is gram negative, the test is successful as the unknown bacteria grown colonies on the EMB Agar. EMB test is also a differential test because it contains lactose, which encourages the growth of vigorous lactose fermenters whose can produce green metallic sheen colonies. The result shown black color colonies on the EMB agar, which indicated that the unknown is not a vigorous lactose fermenters, therefore they are not coliform. PRB Fermentation