Questions

Q1) What are bacteria? List down some characteristics of bacteria.

Bacteria are the most abundant group of microorganisms in nature. It can be found anywhere on the planet, such as the ocean, desert and even inside our intestine!

Some characteristics of bacteria:

  • Bacteria are prokaryotic organisms (Kingdom: Monera), without cell defined organelles such as mitochondria
  • Bacteria are microscopic and unicellular
  • Bacteria posses a rigid cell wall. 
  • Bacteria also has an absence of a well defined nucleus
  • A common method of multiplication is binary fission.

Q2) How can bacteria be identified?

->Gram Staining

This technique is named after a pioneering Danish microbiologist. 
  1. The bacteria are stained with a purple dye (Crystal Violet). Most bacteria are then stained red.
  2. The bacteria are stained again with Potassium Iodide.
  3. The bacteria are then washed with alcohol. Those bacteria that retain the dye after washing are known as Gram Positive bacteria. Those that lose the dye are known as Gram Negative bacteria.
  4. The bacteria are further stained with a pink dye (Safranin). Gram Negative bacteria will go pink after this dyeing, whereas Gram Positive bacteria will remain purple, from the original purple dye.

->Ziehl-Neelsen Staining.

  1. The bacteria are stained with hot Carbol-Fuchsin, a red dye which contains detergents. All bacteria are then stained red.
  2. The bacteria are washed with acid alcohol. Those bacteria that retain the red dye are known as acid-fast bacteria.
  3. The bacteria are then stained with Methylene Blue, a blue dye. Those bacteria that retain the red dye from the original stain are known as acid-fast bacteria, all others go blue.

Q3) Name 3 common bacteria and places where they are commonly found.

Streptococcus Sanguinis (Cocci)
Commonly found in the mouth

Meningitis
Commonly found in the brain and the spinal cord (infection)

Bacillus
Commonly found in soil


Q4) Are all bacteria harmful? If not, name some bacteria useful to humans.

No.

Bacteria as decomposers
Soil fertility

  • Nitrifying bacteria –Nitrosomonas & Nitrobacter
  • Ammonifying bacteria
  • Nitrogen fixing type of bacteria-Rhizobium leguminosarum,Clostridium & Azotobacter
  • Soy sauce-Pediococcus species
  • Cheese-Lactobacillus
  • Vinegar-Acinetobacter species
  • Clostridium felsineum &Clostridium pectinovorum
  • Acetone & Isopropanol-Clostridium species
  • Acrylic acid & Proplene Glycol- Bacillus species
  • Lactic acid bacteria
  • Riboflavin (Vitamin B) - Clostridium butylicum
  • Cobalamine (Vitamin B12) -Pseudomonas denitrificans
  • Bacitracin- Bacillus subtilis
  • Aureomycin – Streptomyces species
  • Terramycin – Streptomyces rimosus
  • Streptomycin-Streptomyces griseus
  • Streptokinase-Streptococcus pyogenes
  • Proteokinase- Bacillus subtilis
  • Amylase-Bacillus species
  • Cornyebacterium & Streptomyces

Food that use bacteria in their production include
Bacteria in various industries
Fibre retting
Industrial production of organic compound
Bacteria in dairy products
Bacteria in the production of vitamins
Bacteria in the production of antibiotics
Bacteria in the production of enzymes
Bacteria in the production of Steroids

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