What is microbiology?  A branch of science that studies a diverse group of small life forms encompassing bacteria, fungi, algae, and protozoa. Viruses are also studied but they are not alive.  The above small live forms are known as microorganisms.  They inhabit almost every known environment on earth!  The survive in thermal vents, on top of the tallest mountain in Antarctica, in the deepest oceans, and in the darkest caves. They even live within you and I.

Why are microorganisms important?  They are essential in the recycling of nutrients that form the bodies of all life forms.  They help control our climate by taking CO2 out of the atmosphere during photosynthesis.  They produce 50% of the oxygen we breath.  They grow on almost every part of our body (bacteria) and most of the time they help us by out competing harmful bacteria.  Many are pathogens which cause diseases.

Pathogens  Microbes cause:  Malaria, Avian Influenza, H1N1, Cholera, Smallpox, the bubonic plague, Ebola, staph infections, seasonal allergies, food poisoning, sinus infections, HIV, herpes, SARS, Anthrax, Tuberculosis, Polio, Measles  Millions of people die from many of these diseases each year  Many of these diseases are curable with antibiotics or preventable with vaccines.  Further understanding of microbes is sought in immunology or the study of the bodily defenses against pathogens.

Spread of the Bubonic Plague

Prevalence of HIV

Malaria

Bacteria  Bacteria are unicellular prokaryotic organisms.  Today there are more than 10 million bacteria species.  Bacteria may be spherical, rod shaped, or spiral shaped.  Most bacteria are heterotrophic, but some perform photosynthesis.

Viruses  Viruses are a strand of DNA or RNA that are surrounded by a protein coat.  There are over 3600 known viruses.  Viruses are NOT made of cells and they cannot replicate on their own. Therefore, they are not alive.  The only reason viruses infect organisms is to reproduce.  Viruses will be discussed in more detail later in the semester.

Influenza

Fungi  Fungi are unicellular yeasts and multicellular mushrooms and molds. They are eukaryotic and have a cell wall made of chitin.  There has been 70,000 species of fungi identified. However, scientists believe there may be as many as 1.5 million species in nature.  Most fungi grow in warm, moist places and secrete digestive enzymes that break down nutrients into smaller bits that can be easily absorbed.

Examples of Fungi MushroomMold

Fungi uses  Fungi can be useful. Fungi are used to make antibiotics which kill bacteria.  Other fungi are used to make flavors of food, specifically different cheeses.

Protista  Protista consist of single celled protozoa and algae.  Protista may be heterotrophic, phototrophic, or both.  Some cause diseases such as malaria, sleeping sickness, and many types of diarrhea.  For a more thorough discussion of protista refer to your previous notes.

Bacteria and Fungi in Microbiology  Nutrient Agar is used to culture bacteria and fungi.  There are many types of Agar each rich in nutrients.  Bacteria or Fungi can come into contact with agar in two ways:  Airborne – simply exposing agar to the air will allow bacteria and fungi in the air to contact the agar.  Swabbing – a swab or cutip comes into contact with an area of interest and then is rubbed on the agar.

Examples of Agar Plates Cladosporium (mold) – non toxicAspergillus niger (mold) - toxic

Examples of Agar plates Bacteria

Telling the difference between bacteria and Fungi  If its fuzzy then it is probably mold.  If it is colored with a white ring around it, then there’s a good chance it is mold.  Everything else is probably bacteria.

Describing cultural characteristics of Agar plates  1. Size: Pinpoint, small, moderate, or large.  2. Pigmentation: Color of colony.  3. Form: The shape of the colony is described as follows:  Circular or round: Unbroken, peripheral edge  Irregular: Indented, peripheral edge  Rhizoid: Rootlike, spreading growth

Cultural characteristics of agar plates  4. Margin: The appearance of the outer edge of the colony is described as follows:  Entire: Sharply defined, even.  Lobate: Marked indentations.  Undulate: Wavy indentations.  Serrate: Toothlike appearance.  Filamentous: Threadlike, spreading edge.

Cultural characteristics of agar plates  5. Elevation: The degree to which colony growth is raised on the agar surface is described as follows:  Flat: elevation not discernable  Raised: slightly elevated.  Convex: Dome-shaped elevation.  Umbonate: Raised, with elevated convex central region.

Cultural Characteristics Agar Plates