Microorganisms

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Microorganisms

• Chapter 24
• Bacteria

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Microorganisms Defined

• Microorganisms can be defined as those
  unicellular and multi-cellular organisms too
  small to be seen with the naked eye.
• Microorganisms are thought to be the descendants
  of the first living organisms on earth.
• Microorganisms are thought to have started life
  as ocean dwellers that utilized organic nutrients
  gathered from the ocean for their existence.

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Microorganisms Defined

• Evidence suggests that these first organisms were
  small, uncomplicated, lacked membrane bound
  organelles and did not have a nucleus.

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Classification of Microorganisms

• In the 6 kingdom system the prokaryotes called
  bacteria are grouped in 2 kingdoms
• Eubacteria and Archaebacteria
• The kingdom Protista are composed of two major
  types of organisms
• Monerans and Algae
• The kingdom Fungi are made up of
• Molds, Yeasts and Lichens

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Science of Microbiology

• Dedicated to the study of the organisms, their
  relationship to other organisms and the
  environment and the impact microbes have on the
  health and well being of the human population.

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Microbiologists

• Scientists who study Microbes and enable us to
  develop an understanding of how microbes effect
  our world.
• Specialized by the type of microbe they study
• Bacteriologist-Bacteria
• Virologist-Viruses
• Mycologists-Fungi

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Tools of the Microbiologist

• The main tools of the microbiologist are
• The light microscope
• Electron microscope
• Instruments used to grow microorganisms for study
• Incubators
• Petri Dishes
• Nutrient Agar
• Stains to locate and identify microorganisms

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Kingdom Archaebacteria

• Make up group of bacteria called Extremeophiles.
  Archaebacteria lack peptidoglycan in their cell
  walls and posses unusual lipids in their cell
  walls.
• Methanogens-acquire energy from the conversion of
  H2 and CO2 into methane gas.
• Halophiles-salt loving bacteria, use salt to
  generate ATP.
• Thermoacidophiles-live in extreme acidic/hot
  environments. (temperatures up to 230 F)

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Kingdom Eubacteria

• 3 Basic Shapes
• Bacilli-bacteria that have rod shapes
• Cocci-Bacteria that are spherical in shape
• Spirilla-Bacteria that are spiral in shape
• Cocci that occur in chains are called
  Streptococci and those that occur in bunches are
  called Staphylococci

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Kingdom Eubacteria

• Divided into 2 groups based on their response to
  a technique called the Gram Stain.
• Bacteria that stain purple are called Gram
  Positive.
• Bacteria that do not take up the stain and appear
  pink are called Gram Negative.
• These bacteria can also be differentiated by how
  they respond to antibiotics.

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Bacteria Groups -4 Phylum

• Cyanobacteria-Cyanobacteria use photosynthesis to
  produce the energy that they need the by product
  is oxygen.
• Spirochetes-Spiral Shaped bacterium Treponema
  pallidum responsible for the sexually transmitted
  disease Syphilis
• Gram Positive Bacteria-Actinomycetes grow in soil
  and produce antibiotics that inhibit or kill
  other organisms
• Proteobacteria-Enteric (Escherichia coli)
• Chemoautotroph-extract energy from minerals and
  gases
• Example Rhizobium-Nitrogen fixing bacteria, get
  energy from nitrogen gas in the atmosphere.

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Bacterial Structure

• 1. Cell Wall-made up of peptidoglycan
• Cell Membrane and Cytoplasm
• Capsules and Pili
• Capsule- outer covering that protect it from
  drying and harsh chemicals
• Pili-hair like surface structure that help the
  bacterium adhere to the cells of the host. Also
  use to transfer genetic information from one
  bacterium to another.
• Endospore-thick outer covering that protects the
  bacteria when exposed to harsh environmental
  conditions.

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Movement

• Flagella are use to move bacteria.
• Bacteria may have 1 or a tuft of flagella
• Spiral shaped bacteria use corkscrew movements
• Some bacteria secrete a slime coat to glide
  through

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Nutrition and Growth

• Bacteria may be heterotrophic or autotrophic.
• Autotrophs-Photoautotrophs obtain energy from the
  sun.
• Chemoautotroph-obtain energy from minerals in the
  environment.
• Heterotrophs
• Saprophytes-obtain energy from dead and decaying
  material.

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Oxygen Requirements

• Obligate Anaerobes-cannot live in the presence of
  oxygen-Ex. Clostridium tetani
• Facultative anaerobes-can live with or without
  oxygen.
• Obligate Aerobes-cannot survive without oxygen.
  Ex. Mycobacterium tuberculosis

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Genetic Recombination

• A. Transformation-DNA taken in from the external
  environment.
• B. Conjugation-Pilus connects two bacterium
  forming Conjugation bridge for the exchange of
  genetic material.
• C. Transduction-Replication of DNA fragments
  within a virus inside a bacterium.

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Bacteria and Disease

• The study of diseases is called Pathology
• Bacteria cause disease by the release of poisons
  called Toxins.

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Bacterial Toxins-2 kinds

• Exotoxins-bacterial excretions into the
  surrounding environment-Tetanus
• Endotoxins-toxins released as result of the death
  and disintegration of bacteria. Cause of body
  ache, weakness and fever.

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Antibiotics

• Antibiotics are drugs that destroy bacteria by
  interfering with either the structure or
  function of the bacterium
• Two common antibiotics are
• Penicillin-bacterial cell wall synthesis
• Tetracycline-bacterial protein synthesis

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Useful Bacteria

• Bacteria are used beneficially in
• Sewage treatment
• The recycling of dead organisms
• Processing foods
• Yogurt, Cheeses, Sour Cream, Alcoholic Beverages
• Pesticides
• Clean up of environmental disasters

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