Question

1. what is the seven practices of biosafety?

2.how to aseptically inoculate a culture, and streak a plate for isolation.

3. Know the names of the following differential tests, the components of these tests (dyes, indicators, sugars, etc), what organisms they test for, what biochemical reactions they test for, and be able to interpret a result.

Phenol red broth (5-2)

Catalase test (5-5)

Nitrate reduction test (5-7)

Citrate test (5-8)

Decarboxylation test (5-10)

Urease test (5-14)

Sulfur, Indole, Motility (SIM) test (5-19)

Triple Sugar Agar (TSI) test (5-20)

Motility test (5-27)

4. Know how to do a gram stain

5. Know the names of the following agars, the components of these tests (dyes, indicators, sugars, etc), what organisms they test for, what biochemical reactions they test for, and be able to interpret a result.

Blood agar (5-25)

Bismuth sulfite agar (BSA)

Answer 1

1) seven practices of biosafety are-

minimum aerosol, hand sanitization and washing, no eatables allowed in working area, hand pipetting not mouth pipetting, sharp objects safety, wear personal protective suits, and decontamination of the working surface before and after work.

2) take a loopful of inoculum near the flame in laminar air flow hood. make five sectors on a petri plate. open the petri plate, containing suitable solid media for growth, in hood and streak first sector with the help of loop. now warm the loop in flame and cool it down then touch the loop to the first sector and streak the second sector. again warm it and repeat the process but make sure that tha first and last sector will not touch each other.

3) phenol red broth used for determination of fermentation studies of different microbes. phenol red turns yellow if microbe ferment sugar.

catalase test used to determine the presence of catalase enzyme in microbes.

nitrate reduction test used to detect presence of enzyme nitro reductase which reduces nitrate to nitrite. pink or red colour is positive.

in citrate utilization test citrate is used as a sole source of carbon for microbes. in positive test green colour turns into blue colour.

in decarboxylation test microbe decarboxylate the amino acid to form amine and CO2 gas been librated.

urease test is used to identify urease enzyme secreting microbes. urea will convert into ammonia and form pink colour with phenol red dye.

4) fix the bacteria on the slide, add crystal voilet solution, remove and wash the slide, add iodine solution, remove and wash slide, decolorize the stain and add counter stain safranin. look in microscope. gram positive look voilet while gram negative look pink.