1. Which of the following antibiotics is produced by bacteria in the genus Strep

Question

1. Which of the following antibiotics is produced by bacteria in the genus Strephtomycetes?

A. Vancomycin

B. Tetracycline

C. Chloramphenicol

D. All

2. Which is not involved in nitrogen fixation?

A. Rhodosprillum

B. Frankia

C. Rhizobium

D. All fix nitrogen

3. What type of pattern of hemolysis when grown on blood agar does S. epidermidis exhibit?

A. alpha hemolysis

B. beta hemolysis

C. gamma hemolysis

D. delta hemolysis

4. Members of this genus can exist not only as pairs, but as tetrads, or irregular clusters?

A. Bacillus

B. Micrococcus

C. Rickettsia

D. None

5. Species of the genus Hyphomicrobium:

A. Are found in marine and freshwater environments

B. Aerobic chemoheterotrophs

C. Able to reproduce by budding

D. All

Explanation / Answer

1. D. All

Vancomycin: It is a glycopeptide antibiotic obtained from Streptomyces orientales.

Tetracycline: Obtained from Streptomyces aureofaciens and other streptomyces species.

Chloramphenicol: Obtained from Streptomyces venezulae.

As all the given antibiotics are obtained from Streptomycetes, the answer is D. All

2. D. All fix nitrogen

Nitrogen fixation is a process where gaseous form of Nitrogen is converted into combined forms like ammonia or organic nitrogen by some bacteria and cyanobacteria collectively called as Diazotrophs. This phenomenon is termed as Diazotrophy

Rhodosprillum: Rhodospirillum rubrum is a gram negative proteobacterium which is a nitrogen fixing bacteria which can express and regulate nitrogenase

Frankia: Different species of Frankia like F. alni, F asymbiotica, F, californiensis, F. casuarinae, F. coriariae, F. discariae etc are specific to certain dicotyledonous species and are also nitrogen fixing bacteria

Rhizobium: It is found in the root nodules of legumes of fabaceae family and are also capable of nitrogen fixation

Hence, the answer is D. All fix nitrogen

3. C. Gamma hemolysis

Gamma hemolysis is the one where there is no hemolysis and blood agar remains unchange around the colony. Staphylococcus. epidermidis, S. saprophyticus, Enterococcus faecalis exhibit gamma hemolysis

Alpha hemolysis is exhibited by Streptococcus pneumoniae, Streptococcus viridans and colony appears dark and green in color due to incomplete hemolysis

Beta hemolysis is shown by Streprococcus dysgalactiae, S. pyogenes, where there is complete hemolysis

Delta hemolysis called as Double zone hemolysis is exhibited by Staphylococcus aureus

4. B. Micrococcus

Micrococcus are gram positive, obligate aerobe found in soil, dust, water, air and normal flora of mammals. They occur as pairs, tetrads or irregular clusters

Bacillus occur as single chains (B. subtilis) or curved or spiral (Ex Treponema palladium)

Rickettsia are rod shaped or spherical.

Hence the answer is Micrococcus

5. D. All

Hyphomicrobia are aerobic bacteria and exhibit similar morphology to Rhodomicrobium. These are prosthecate budding bacteria and found in soil and aquatic environments (found in marine and freshwater environments). They are initially coccoid, flagellated and mature into oval or bean shaped cells and are chemorganotrophic

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