Can you help me to answer what is the organism is? and explain why. Thanks. The

Question

Can you help me to answer what is the organism is? and explain why. Thanks.

The Microbiology Lab performed the following biochemical tests on isolated colonies fro th plates. The results from the tests are listed below: 3. Nutrient broth grown at 35oC- turbid Nutrient broth grown at 4oC-not turbid Oxidase test-colony turns black Nitrate test-broth is turbid and turned red after addition of reagents to test for reduction of nitrate Phenol red Glucose fermentation broth-turbidity and yellow color, no bubble in durham tube Phenol red Lactose fermentation broth-turbidity and red color, no bubble in dirham tube Phenol red sucrose fermentation broth-turbidity and turned yellow, no gas in durham tube VP test-broth is turbid and has red color at the top after adding reagents 4, using the biochemical tests in #3, what organism (Genus and species) is causing the infection?

Explanation / Answer

As you see in the results in test #3 gives you an indicator of the characteristics of the organism. Let's understand them one by one

Nutrient broth grown at 35C was turbid but at 40C was not turbid. This means that your organism is a Psychrotroph that is, it likes to grow in temperature range of 20 - 35 C.

Oxidase colony test turns black- This means your organism is oxidase positive or your organism is either aerobic or facultative anaerobic

Nitrate broth is turbid and turned red after addition of reagents. This indicates that your organism has the ability to produce nitrate reductase enzyme, a characteristic of Enterobacteriacease family and is gram negative.

From phenol red tests, it can be concluded that your your organism is lactose fermenter, but does not utilize carbohydrates (as no gas is produced) but peptone in phenol red broth. So your organism should be one of the Escherichria or Enterobacter from Enterobacteriacease family

VP test broth is turbid and turns red on adding reagents. This confirms the presence of Enterobacter Cloacae.

So based on experimental results of #3 your organism is Enterobacter Cloacae.

Family - Enterobacteriacease, Species- Enterobacter Cloacae

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