Microbiology

The World Of Microbiology

This is one subject which I require to study in my course, Biotechnology. It is fascinating to learn that there are all kinds of bacteria. Once in Introductory Microbiology, we had to take some sample, be it from the left over food, soil, water or body. I took my sample from some part of my body, my...NOSE! I always have sinus and running nose, out of curiosity, I took my m*cus.

This is gonna be a learning page. Nah! It’s not going to be some lecture, just some short notes and facts.

What is Microbiology?

What are Microorganisms?

Types of Microbes

Cell Size and Shape

Prokaryote vs. Eukaryotic Cells

Classification andDefination

Cell Structure

Classification of Microbes

Effect & Types of Environment Factors

Temperature & Growth

pH & Growth

Principles of Aseptic Technique

Simple Staining with Basic Dyes

What are microorganisms?
It is the study of microorganisms.

What are Microorganisms?
They are very small living things which cannot be seen with the naked eye. They are cells which requires the light microscope in order to be seen. Microorganisms, also known as microbes exist as single or clusters of cells which can grow or reproduce.

Types of microbes
Bacteria, Fungi, Algae, Protozoa, Slime Moulds, Viruses, Viroids and Prions. Do not think it is that little, because under each category as listed above has many , many more organisms listed under them. For example under Bacteria, they are all kinds of bacteria, I don’t mean just hundred but many even may add up to over a thousand kinds. For Bacteria, you can find all kinds of microbes in the Bergey’s Manual , where all microbes are well divided into various categories.

Cell Size and Shape
Size of microbes are measured in micrometer. Bacteria size usually ranges from 1um to 2 um wide, 1um to 5 um long. Bacteria comes in various shapes as well. There is Cocci (spherical), Bacilli(long rods), CoccoBacilli (very short rods), curved, spiral, swollen and appendaged.

Prokaryotic Vs. Eukaryotic cells.
Eukaryotic cells are usually much bigger than the prokaryotic cells. They varies from 2 um to about 200 um. They are usually larger as Eukaryotes have more than one chromosomes whereas the Prokaryotes have 1 chromosome. In comparison, Eukaryotes have more DNA and contains Organelles. Prokaryotes on the other hand, has got no nuclear membrane and cellular functioning occurs in the cytoplasm and the cell membrane.

Classification and Definition.
Classification
  1. Autotroph (microbes which do not require external organic compounds)
    • Photoautotroph (microbes which requires light as energy.)
    • Chemoautotroph (microbes which requires Inorganic compounds)
  2. Heterotroph (microbe which requires Organic compounds or light)
    • Photoheterotroph (microbes which requires light and uses organic cpds instead of CO2 )
    • Chemoheterotraph (microbes which requires Organic compounds)


Definitions

  1. Strict/Obligate - Unable to switch between different metabolic patterns.
  2. Facultative - Able to switch between metabolic patterns.

For an example, Strict Aerobes means that Microbes are able to grow ONLY in the presence of O2 , Strict Anaerobe means microbes are able to grow only in the absence of O2. Facultative aerobe would mean that the microbe is able to grow in the presence or absence of O2.

Cell Structure
Prokaryotic Cell has:
  1. Cell membrane 7. Fimbriae
  2. Cell wall 8. Sheaths
  3. Ribosomes 9. Nuclear region ( but has no nuclear membrane)
  4. Gas vacuoles 10. Spores & endospores
  5. Inclusion bodies 11. Pili
  6. Flagella 12. Capsules

Eukaryotic Cell - has the following organelles

  1. Nucleus ( with nuclear membrane) 5. Mitochondria
  2. Endoplasmic reticulum 6. Golgi body
  3. Lysosome 7. Chloroplast ( in plant cells)
  4. Storage bodies

Classification of Microbes
1.1 Cellular ( Bacteria, Fungi, Algae, Protozoa, Slime Moulds)
Acellular ( Viruses, Viroids, Prions)

1.2 Prokaryote - does not have a nucleus membrane
Eukaryote - has a nucleus membrane

1.3 Archaebacteria - has a different cell chemistry from normal microbes. It is primitive in extreme environments.
Eubacteria - it is numerous, ubiquitous, diverse anaerobic, aerobic, alkalinophilic, acidophilic, thermophilic, psychrophilic, autotrophic, lithotrophic, heterotrophic, photosynthetic, saprophytic, parasitic

Effect of Types of Environmental Factors
Microbial composition of an environment
Rate of Growth or Product Formation
Enrichment of Isolation Techniques
Evolution of microbes
Methods of preventing or enhancing microbial growth
Susceptibility of a media tocontamination

Temperature and Growth
  1. No microbial growth at & below minimum temperatures
  2. No Microbial growth at & above maximum temperature
  3. Rapid Microbial growth at Optimum temperature ( which is always closer to the maximum temperature)

    pH & Growth
    Most Microbes have pH optima of 6-8 e.g. E.Coli , Strep. Lactis , Rhizobium spp.

    Acid tolerant microbes grow at pH 3-4 e.g. Acetobacter spp, Lactobacillus spp

    1. Acidophiles are able to grow below pH2 (Some are Obligate acidophile - they require very low pH)
    2. Alkaliphile are able to grow at an optimum pH of 10-11



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    Want to have a look at some pictures on bacteria? Click here
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