# 2. You inoculate strain SOS into a Fluid Thioglycollate Media tube and a semis
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# 2. You inoculate strain SOS into a Fluid Thioglycollate Media tube and a semisolid agar tube. After doing some research on the strain, you discover that SOS in an obligate anaerobe that is non-motile. Draw the expected growth of strain SOS in the two media types: FTM & Semisolid
(8 pts) You are working in a microbial genetics laboratory studying lactose transport proteins. The bacterial strain you are working with, Escherichia coli strain SOS, has a mutated lactose transporter that does not transport lactose into the cell. You streak the bacterium onto an EMB plate and incubate at 37C for 48 hours. Describe what would be seen on the plate, and interpret these results. (2 pts) 1.) 2.) You inoculate strain SOS into a Fluid Thioglycollate Media tube and a semisolid agar tube. Afte doing some research on the strain, you discover that SOS is an obligate anaerobe that is non- motile. In the space below, draw the expected growth of strain SOS in these two media types. (1 pt) [staple this sheet to the front of your typed post lab] FTM Semisolid: 3.) You are working in a microbiology laboratory that is developing a media type to isolate certain types of bacteria. The types of bacteria you are trying to isolate are Gram-positive, motile, halophilic, mannitol fermenters that grow in the presence and absence of oxygen. What form of media would you use (tube or plate)? What components would you include in the media that would favor the growth of these types of organisms? List all components below and what purpose each component serves (selective, differential, indicator, etc.): (3 pts) 4.) You streak an unknown bacterium on an EMB agar and incubate at room temperature. After 48 hours of incubation, you observe NO growth on the plate. Is this unknown bacterium a lactose fermenter? Explain your answer. (2 pts)Explanation / Answer
1). MacConkey’s (MAC) medium selectively allows the growth of gram-negative bacteria. It is used to differentiate the enterobacteria by their lactose fermentation ability. Gram-positive bacteria cannot grow in MacConkey’s medium due to the presence of bile salts and crystal violet. E.coli is an enterobacter species and can ferment lactose. So, it produces pink colonies on MacConkey’s medium. While the Salmonella typhimurium does not ferment lactose, so they produce yellow to light pink color colonies.
In the given case, the E.coli has mutated lactose transporter, so does not ferment lactose. This results in the formation of colorless colonies.
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