Based upon your results, is your bacteria sample a strict aerobe, strict anaerob
ID: 49899 • Letter: B
Question
Based upon your results, is your bacteria sample a strict aerobe, strict anaerobe, facultative anaerobe, or microaerophile? Why? – Look at your results from OF Glucose and OF Glucose with oil test.
How important is it to add the Kovac’s Reagent in the Indole Utilization test? What is responsible for the color change observed in a positive test? –You can read more about this test in the Test Media Reference in VUMIE2012. Click the M? button.
Kovac’s reagent consists of p-dimethylaminobenzaldehyde dissolved in HCl. The reagent is added to an overnight culture of the unknown in tryptone broth. Development of a red ring atop the broth is indicative of the production of indole, a breakdown product in the digestion of the amino acid tryptophan.
Did the bacteria grow in the tryptone or malonate media? Why or why not? – Remember, you can tell if they grew if culture was turbid (cloudy).
For the media used in this portion of the experiment, are the media complex or synthetic? Are the media selective, differential, both, or neither? Identify the carbon and nitrogen source for each medium. – Read more about what these terms mean starting on page 178 in your book right below Figure 6.11. Look up each media with the M? button. Remember, nutrient broth is a complex media, mineral salts is a defined media.
How many possible bacteria were remaining after conducting these biochemical tests?
Using the information in the Identification matrix, what additional tests might help you to identify the bacteria in your case study? –Look at the View Identification Matrix under the View menu. What tests would you perform? Look for ones that have a mix of + and – because they would help distinguish between organisms.
Explanation / Answer
1. Organisms that grow in the presence of oxygen are known as aerobic organisms and that can grow in the absence of oxygen are known as anaerobic organisms.
The term facultative aerobes is used to organisms that can produce energy by utilising oxygen if it is present, but can also shift the metabolic process to anaerobic mechanism in the absence of oxygen. In contrast, obligate aerobes need the strict presence of oxygen for survival. Obligate anaerobes (fermentative), can grow in the absence of oxygen, they cannot survive in the presence of oxygen and facultative anaerobes can grow both in the presence and absence of oxygen.
To test wheather an organism is aeobic or anaerobic (oxidative or fermentative), we perform O/F glucose test and O/F glucose with oil test (O/F = Obligate/Fermentative). In this 2 O/F glucose test tubes are taken one with oil layer (anaerobic) and the other without oil layer (aerobic).
If the organism is oxydative, it turns the test tube without oil into yellow colour and the other test tube remains same (no colour change). Most of the oxidative microbes are obligate aerobes.
If the organims is facultative aerobe or anaerobe, it turns both test tubes into yellow (it performs fermentation).