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1. MacConkey\'s media is a selctivave and differential medium has three broad ou

ID: 200829 • Letter: 1

Question

1. MacConkey's media is a selctivave and differential medium has three broad outcomes: pink colonies, colonies that aren't pink, and no growth. (2 points) a. What are the pink colonies using for carbon and energy on MacConkey's Agar? b. What are the white colonies using for carbon and energy on MacConkey's Agar? c. If an organim doesn't grow orn MaConkey's agar, but s grow on lactose minimal media, what is your prediction for a lactose fermentation tube? doe If an organism grows pink on Mac not on glucose minimal media what is your prediction for growth on a lactose minimal media? d. Conkey's agar, but 2. L. ipsum can grow anaerobic jars. What is your prediction for a L. ipsum catalase result? What is your prediction for a L. ipsum oxidase result? (1 point) a. Catalase on TSA in the open air, and in b. Oxidase

Explanation / Answer

3. Answer : Agar consists of a mixture of two polysaccharides: Agarose and Agaropectin, with agarose making up about 70% of the mixture. Agarose is a linear polymer, made up of repeating units of agarobiose, a disaccharide made up of D-galactose and 3,6-anhydro-L-galactopyranose. Agaropectin is made up of alternating units of D-galactose and L-galactose heavily modified with acidic side-groups, such as sulfate and pyruvate.

Agar exhibits hysteresis, melting at 85 °C (185 °F) and solidifying from 32–40 °C (90–104 °F).This property lends a suitable balance between easy melting and good gel stability at relatively high temperatures.Agar is more appropriate than other solidifying agents that melt at this temperature.