Question

30. The most effective means of sterilization is _________________________.

31. Are commercially canned foods sterile?

32. What is the most important organism to eliminate from canned foods?

33. What kind of organism stains with the Ziehl-Neelsen method?

34. What is the primary dye in the stain mentioned in the prior question?

35. What is the color of an organism that retains the primary dye?

36. Name a species that will stain with the primary dye in this stain?

37. What is the decolorizing agent in this stain?

38. What is the counterstain in this stain?

39. Name 3 uses for solid media.

Answer 1

Sterilization : It is a method of removal of microorganisms from the target (food, equipment, process, etc.).

30.The most effective means of sterilization is Moist heat sterilization.

31. Canning is a process where the desired food is heated and sealed in vaccum. Heating is to kill all aerobic and anaerobic microorganisms and vaccum will removes air. Presence of air in the can helps the microorganism to multiple. So, we can say commercial canned foods are Sterile. But we must ensure that the canning process was done properly.

32. Clostridium botulinum is the microorganism to be eliminated from the canned foods.

Ziehl-Neelsen Method:

This is used to differentiate bacteria like Mycobacteria species. The cell wall of this bacteria are having thick mycolic acid which acts as a barrier and won't allow primary stain to wash out while treated with acid alcohol. In this Carbol fuchsin is the primary stain and Methylene Blue is the secondary stain.

33. ACID FAST BACTERIA (Mycobacterium Species) are stained with this method.

34. Primary dye is Carbol fuchsin.

35. Color of the organism which retains primary stain is RED.

36. Mycobacterium tuberculosis and Mycobacterium lepra.

37. Decolorizing agent is Acid Alcohol.

38. The counter stain is Methylene blu.

Solid Media: The base where one can grow microorganisms and isolate easily is called as solid media. Agar is used as a solidifying agent.

39. Three uses of solid media - 1. Microbial colonies can be identified and easily counted.

2. Isolation of pure single colonies can done from a mixed microorganisms.

3. We can prepare agar plates and agar slants with solid media.

4. Different cultural characters of the microorganism can be seen.

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