Micro Lab Test 3

An obligate aerobe is an organism that requires oxygen for aerobic respiration. Facultative anaerobes can switch between aerobic and anaerobic respiration, aerotolerant organisms can survive in the presence of oxygen but do not use it for respiration, and obligate anaerobes cannot survive in the presence of oxygen.

The correct answers provide the accurate method, purpose, media, reagents used, and interpretation of results for the Carbohydrate Fermentation & Gas Production Test, while the incorrect answers deviate from the correct procedure, purpose, and components required for the test.

Carbohydrate Fermentation & Gas Production Test can have different results based on the acid and gas production. It is important to interpret the results accurately to determine the metabolic activity of the organism being tested.

The correct way to perform the Mixed Acid Fermentation Test is by inoculating the broth with a loop and adding a methyl red indicator to indicate the acid end products.

In a Mixed Acid Fermentation (MR) Test, the correct result sequence is control, negative, positive. This order is crucial in determining the presence of certain fermentation pathways in bacteria.

The correct method involves inoculating the slant with a needle and stabbing it to introduce the bacteria. The expected result for positive (+) is a blue color, indicating the metabolism of citrate. A negative result (-) is indicated by no color change, remaining green.

In the Citrate Test, a positive result is indicated by a blue color, while a negative result is indicated by a green color. This color change helps in determining the utilization of citrate by the microorganism being tested.

The correct answer involves inoculating urea broth with a loop for the test.

In urea hydrolysis test, the activity of the enzyme urease is being tested. If urease is present, it will break down urea into ammonia and carbon dioxide. The positive result is indicated by a change in pH due to the presence of ammonia, turning the indicator pink in the 1st tube. The 2nd tube remains yellow as it is negative.

The correct answer explains the step-by-step process of the Tryptophan Degradation Test and how to interpret the results, while the incorrect answers describe unrelated tests with different procedures and outcomes.

The Tryptophan Degradation Test results in a positive color change when Tryptophan is degraded, indicating the presence of the enzyme Tryptophanase.

The Catalase Test involves streak plating colonies, adding H2O2, observing for bubbling to test for the bacteria's catalase production. The incorrect answers provided deviate from the correct test procedure and purpose of the Catalase Test.

The correct way to perform the Starch Hydrolysis Test is to divide the starch plate in 2 parts, streak control on one side and bacteria specimen on the other.

In a Starch Hydrolysis test, the left side will show a negative result (-) indicating the absence of starch hydrolysis, while the right side will show a positive result (+) indicating the presence of starch hydrolysis.

Peritrichous flagella are flagella that are distributed over the entire surface of a cell. They allow the cell to move in a variety of directions in response to stimuli.

After finding a gram + Rod, the next steps would typically involve confirming the bacteria identification through additional staining techniques such as spore stain (if + you are done) or Acid Fast stain, rather than using Gram stain, Ziehl-Neelsen stain, or Dark-field microscopy.

After finding out you have a gram + cocci, the correct steps involve performing a spore stain test (if +, no further testing is needed; if -, proceed to a catalase test). Conducting a gram - stain, skipping further testing, or performing a blood culture test are not the appropriate steps in this scenario.

The citrate test is commonly performed after a motility test and can help in differentiating bacteria based on their ability to utilize a citrate source. Oxidase, urease, and coagulase tests are not typically performed immediately after a motility test.

The correct answer involves a specific sequence of tests based on the results of the motility test, which is essential for identifying the characteristics of the gram - rod. The incorrect answers are not relevant to the testing process described in the question.

Gram-positive bacteria are typically characterized by their lack of motility, meaning they do not possess flagella or other means of movement. However, they can vary in terms of other characteristics such as being anaerobic, rod-shaped, or spore-forming.

Serratia marcescens is a Gram-negative bacterium known for its red pigment prodigosin. It is a facultative anaerobe and is commonly associated with hospital-acquired infections, particularly UTIs, catheters, and wounds. Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii are also common pathogens but do not exhibit all the characteristics mentioned in the question.

Micrococcus luteus fits the description provided as a gram-positive obligate aerobe. Staphylococcus aureus is also gram-positive but not an obligate aerobe. Escherichia coli is gram-negative and Pseudomonas aeruginosa is a gram-negative opportunistic pathogen, not an obligate aerobe.

Streaking cultures for isolated colonies is a common method used in microbiology to obtain pure cultures of bacteria for further analysis. By streaking a sample onto a solid growth medium, individual colonies are allowed to grow separately, helping to separate mixed cultures, purify a single type of bacterium, propagate a clonal population, and aid in the identification of the bacterium.

The major organelles of motility usually refer to flagella, which are responsible for movement in many microorganisms. The flagellatube on the left would show positive motility because flagella are expected to be present and functional in that sample.

The correct term for the result of obtaining a single cell is a pure colony, as the objective is to isolate a population of identical cells for further study or analysis.

Fermentation is the correct answer as it refers to the metabolic process that produces chemical changes in organic substrates through the action of enzymes. Oxidation, combustion, and photosynthesis are incorrect as they involve different processes than the partial breakdown described in the question.

The catalase test is used to differentiate bacteria based on their ability to produce the enzyme catalase. In this case, a positive catalase test would indicate the presence of a Gram + cocci that does not form spores.

Gram-positive cocci would suggest Staphylococcus or Streptococcus species, but further information is needed before taking any specific action.

Gram positive rods that form spores do not have a specific 'next step' in terms of a biological process.

Gram + rods that do not form spores and are acid fast are typically known for their characteristic acid-fast staining due to the high mycolic acid content in their cell walls.