Microbiology Notes

Microorganisms

  • Definition: Any creature smaller than a tenth of a millimeter. Millimeters are the smallest marks on a metric ruler.
  • Must be viewed with a microscope.
  • Most of the class focuses on pathogenic (disease-causing) microorganisms.

Bacteria

  • Always microscopic.
  • Length: 1-10 microns (a micron is a millionth of a meter).
  • Must magnify image by at least hundreds of times to see them with a microscope.
  • Always single-celled.
  • Prokaryotic: Simple, no nucleus, and generally no organelles.
  • Second-fastest reproducing microorganism; viruses reproduce faster.
  • Reproduce asexually (binary fission): Copy chromosome and divide.
  • Can reproduce when four hours old if conditions are good.
  • Fastest reproducing bacteria can reproduce in about 20 minutes.
  • Ubiquitous: Found everywhere (surfaces, soil, bodies of water, on/in plants and animals, in the air).
  • Classified as one of the top infectious agents (top predators).
  • 99% are harmless and improve the Earth; we require them to live here.
  • About 1% are pathogenic.
  • Pathogenic bacteria:
    • Infect: grow inside us and cause damage.
    • Intoxicate: poison us.
    • Often do both.
  • Discovered in the late 1600s by Antoni van Leeuwenhoek.
  • Proven to cause sickness and death in the late 1800s by Dr. Koch.

Viruses

  • Also considered a top predator and infectious agent.
  • All viruses are infectious and are parasites.
  • Not all viruses prefer humans.
  • Microscopic.
  • Size: 20-1000 nanometers (a nanometer is a billionth of a meter).
  • Must magnify the image by tens of thousands of times.
  • Requires a special microscope called an electron microscope to view them.
  • Proven to exist in the late 1930s with the invention of the electron microscope.
  • Not cellular and considered non-living pathogens (except when actively infecting).
  • Do not have cells or organelles.
    • Have genetic material (DNA or RNA).
    • Have a protein capsid on the outside.
      • Non-enveloped viruses: Have only genetic material and a protein capsid.
      • Enveloped viruses: Have genetic material, a protein capsid, and a fatty envelope on the outside.
  • Fastest reproducing microorganism; can reproduce almost immediately after creation.
  • Reproduce asexually by "rape" of their victim cell. Acquire everything they need from their host.
  • Considered obligate intracellular parasites (always terrorists).
  • Ubiquitous: Found everywhere (surfaces, soil, bodies of water, on/in plants and animals, in the air).
  • Attack by infection, not intoxication (do not poison).
  • Proven in the 1970s to cause cancer.
  • 15% of cancers are caused by viruses, and cancer can be spread/caught.
  • Number one cancer-causing family: Herpes family (thousands of species).

Protozoa

  • Third most common infectious agent in humans.
  • Always microscopic.
  • Length: 10-100 microns (larger than bacteria).
  • Need to magnify the image by hundreds of times to see them well.
  • Always single-celled creatures.
  • Eukaryotic: complex, have a nucleus and organelles.
  • Most reproduce asexually (don't need a mate, sperm, or eggs).
  • Some species can reproduce sexually (rare), requiring the same species to fuse their cells and nuclei.
  • More picky about where they live; require more moisture and water than bacteria.
  • 99% are harmless.
  • 1% are pathogenic, and can infect and/or poison.

Fungi

  • Fourth most common infector in the United States.
  • 99% are safe and pose no threat; the Earth depends on them.
  • 1% or less are pathogenic.
  • Three major classes of fungi:
    • Yeasts: Single-celled and microscopic.
    • Molds: Multicellular and microscopic.
    • Mushrooms: Multicellular and macroscopic (big).
  • More pathogens from the yeast category, but infectious molds exist.
  • No mushrooms are infectious.
  • All three categories can have poisonous species.
  • Any fungus that grows in/on our body will always grow in yeast form.
  • Cell size: 10-100 microns (like protozoa).
  • Eukaryotes (have a nucleus and organelles).
  • Yeasts reproduce asexually, while molds and mushrooms can reproduce sexually and asexually.
  • Molds and mushrooms use spores for reproduction.
  • When molds do sex or mushrooms do sex it has to be of the same species and they must fuse their nucleus together.
  • Terrestrial land dwellers.
  • If there is a fungal/yeast infection, they are usually infecting and poisoning at the same time.

Worms (Helminths)

  • Big as adults, but microscopic as larvae (babies).
  • Cell size: 10-100 microns.
  • Multicellular animals.
  • Eukaryotic (have a nucleus and organelles).
  • Sexual reproduction (sperm and eggs needed, same species).
  • Some worms are hermaphrodites (both male and female parts that both work), but most are not.
  • Live in soil, among vegetation, in waters, and in/on animals.
  • 99% are harmless.
  • 1% or less that have been discovered are actually dangerous or pathogenic to us

Algae

  • Microscopic algae and large algae like seaweeds.
  • Single-celled and multicellular algae exist.
  • Most common algae are single-celled and microscopic.
  • Aquatic (water dwellers).
  • Never infect, but there are poisonous algae (intoxicating).
  • Eukaryotes (have a nucleus and organelles).
  • Cell size: 10-100 microns.
  • Most algae are asexual.
  • 1% or less are dangerous to us.
  • Poisoning examples: Contaminated drinking water, eating food from poisoned water, bathing/swimming in poisoned waters, vapors.

Arthropods

  • Insects or arachnids (ticks, flies, fleas, mites, mosquitoes, lice).
  • Common vector (spreader) of infection.
  • Macroscopic (big).
  • Multicellular animals.
  • Eukaryotes (have a nucleus and organelles).
  • Cell size: 10-100 microns.
  • Always sexual (sperm and eggs, same species).
  • Found among the soil, waters, and some can fly.

Microorganisms in Extreme Environments

  • Found in extremely hot, cold, salty, pressurized, and pH environments.
  • Recently, a mysterious germ was found on a spacecraft in space.
  • Species of bacteria, fungi, and algae can tolerate these environments.
  • Usually, these microorganisms don't infect humans because we don't live in these environments.
  • Earth is dominated by bacteria in terms of number and diversity; the Earth belongs to them.
  • We can live here because of our immune system and medications.

Types of Microscopes in Microbiology

  • Bright Field Microscope
    • Uses a light bulb and glass lenses.
    • Magnifies up to 1000x.
    • Allows you to see bacteria and bigger.
    • Cheap and easy to learn.
    • Supposedly invented in the late 1500s.
    • Requires killing and staining the specimen to see them, which is a disadvantage.
  • More Expensive types (darkfield and phase contrast):
    • More expensive and require more training.
    • Better light and contrast control.
    • Have special condensers and lenses.
    • Can look at living microorganisms.
    • Don't necessarily have to stain the microorganism to see it.
    • Darkfield: Background is black, microorganism is illuminated.
    • Phase contrast: Extreme contrast control of the picture.
    • Both allow you to see bacteria and bicker
  • Fluorescence Microscope
    • Uses ultraviolet (UV) light (not a regular light bulb).
    • UV light penetrates the specimen better, providing better detail and clarity.
    • Requires special eyepieces to protect eyes from UV light.
    • Usually wired to computers to view the image.
    • Allows you to see bacteria and bigger.
    • More expensive and require more training.
    • Can be used with living or killed microorganisms, sometimes stained, sometimes not.
  • Confocal Microscope
    • Uses laser light (infrared light), which is a great penetrator.
    • Provides much better images than previous microscopes.
    • Requires special eyepieces.
    • Usually wired to a computer.
    • Allows you to see bacteria and larger.
    • Can be used with living or killed microorganisms, sometimes stained, sometimes not.
    • Expensive and requires more training.
  • Acoustic Microscope
    • Uses ultrasound technology and computers to produce an image.
    • Outrageously expensive and difficult to use, requires special training.
  • Electron Microscope
    • The strongest and best microscope for microbiology.
    • Invented in the late 1930s.
    • Uses electron beams (not a bulb) and electron lenses (not glass lenses).
    • Very expensive (cost as much as a nice car) and requires special training.

Different Fields of Microbiology

  • Taxonomy: Naming, grouping, and classifying microorganisms.
    • Important because it gives an idea of how life on earth works, how human cells and tissues function, and knowledge of your enemies/predators.
  • Phycology: Study of algae.
  • Mycology: Study of fungi.
  • Protozoology: Study of protozoa.
  • Parasitology: Study of only parasites (larger than bacteria).
  • Virology: Study of viruses.
  • Metabolism: Study of chemical reactions inside microorganisms.
    • Important because it helps understand how life on Earth works, how chemical reactions were discovered in us, and how to develop drugs to fight them.
  • Epidemiology: Study of what diseases are out there, where they are found, why they are there, numbers, causes, prevention/slowing, and when cases spike.
    • Relies heavily on statistics and calculus.
  • Etiology: What causes the infection.
  • Infection Control: Any and all methods to slow or stop that infection.
  • Chemotherapy: Using medicine to treat a disease (in this class, infection or poisoning).
  • Food and Beverage Technology
    • Many favorite foods and beverages are produced by microorganisms.
    • Keeping our foods and beverages safe from pathogens (recalls).
  • Environmental Microbe
    • Life on Earth would not be possible without microorganisms; they are the base of the food chain on land and in water.
    • Without microorganisms, there would be no plants, animals, or life on Earth.
  • Biogeochemical Recycling
    • Microorganisms help to return essential elements (carbon, nitrogen, oxygen, sulfur, and phosphorus) back to the Earth (soil, water, and air).
    • Microorganisms are decomposers; they break down dead stuff and toxic stuff.
  • Industrial Microbe: Using microorganisms to produce industrial products for businesses, factories, and products (chemicals, cleaners, fuels).
  • Pharmaceutical Microbiology
    • Most of our medications come from plants, bacteria, algae, or fungi, either directly or indirectly.

Bragging on Microorganisms (99%)

  • Form the base of the food chain on land and in waters; without them, there would be no life on Earth.
  • Ruminant animals can only digest fiber because of microorganisms in their gut.
  • Decomposers: Break down waste, toxins, and dead stuff (bacteria, protozoa, fungi, algae, worms).
  • Biogeochemical recycling: Constantly return carbon, nitrogen, oxygen, sulfur, and phosphorus back to the soil, waters, and air. They recycle elements back to the earth.