Microorganisms

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Microorganisms
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Microbes

• too small to be seen with the naked eye
• aggregations or colonies can be seen without the
  aid of a microscope

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Microbes

• are found almost anywhere
• are more abundant than any other life form
• they are forms on which all others depend.

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Recycle elements required for life

• N - Nitrogen
• O - Oxygen
• P - Phosphorus
• S - Sulfur
• C - Carbon

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Microbes produce

• food
• fuel
• air

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4 major categories

• bacteria
• fungi
• protists
• viruses

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Pathogens

• disease causing agents
• AIDS - Acquired Immune Deficiency Syndrome
• Botulism - food poisoning
• Tuberculosis
• Polio

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Pathogens

• Typhoid FeverSyphilis

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Disease

• Microbes cause disease by directly damaging
  tissues and weakening bodily functions or by
  producing toxins that do.

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Pathogenic microbes

• the proportion of pathogenic microbes on earth is
  very small

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Producers

• produce carbohydrates
• break down starch into sugar
• convert sugars into alcohol

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Water Dwelling microbes

• algae and bacteria
• largest producers of carbon containing compounds
  through photosynthesis

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Some microbes

• are unable to take in Carbon Dioxide from the
  air.
• They get Carbon from bicarbonate in the water

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Ion

• an atom that carries a positive () or a negative
  (-) charge
• carries the charge because it has gained or lost
  one or more electrons

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Microbes use CHOs (carbohydrates)

• synthesized during photosynthesis (Ps) to make
  cell structures and as an energy source
• Provide food for larger organisms
• Replenish Oxygen supply

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Single Celled Fungi

• Yeasts
• Producers in wine making, bread baking or beer
  brewing.
• Convert sugar to alcohol in fermentation process

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Cheese Making

• bacteria convert lactose (milk sugar) to lactic
  acid

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Contribute to production

• of food and other substances by their enzymes

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Enzymes

• organic molecules that speed up biochemical
  reactions without being used up or becoming part
  of the end product.
• A catalyst - causes a reaction to take place

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Examples

• foods
• medicines
• vitamins
• leather processing
• textile production

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Decomposers and Recyclers

• worlds greatest recyclers
• Keep elements like C and N cycling through the
  environment
• Used to treat sewage, clean up toxic wastes,
  processing materials

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Recyclers

• more than one type of bacterium is needed to
  convert atmospheric N into a form useable by
  plants.
• Requires three different chemical reactions.

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Production through decomposition

• Methane - decomposition of organic matter
• Methanogens - swampy areas, land fills, digestive
  tract of ruminants.

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Production through decomposition

• Linen fabric is made from flax stems
• Stems are immersed in water
• Bacterium digests pectin that makes the stalks
  stiff

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Linen Fabric Production

• remainder is washed dried and spun into thread
  and then woven into fabric

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Basic features of MOs (microorganisms)

• 4 major groups
• bacteria, fungi, protists, viruses
• Viruses are not made up of cells and are not
  considered organisms by many microbiologists.

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Bacteria, fungi and protists

• have a cellular structure, a membrane surrounding
  cytoplasm

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Protists

• have an inner compartment nucleus
• DNA in non circular chromosomes
• unicellular or multicellular
• protozoans, algae, others resemble fungi

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Fungi

• have cellular structure
• non circular chromosomes
• in fungi with many cells, walls between cells are
  sometimes not complete
• cytoplasm and nuclei can stream from one cell to
  another within slender filaments of cells called
  hyphae

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Fungi

• have cellular structure
• non circular chromosomes
• in fungi with many cells, walls between cells are
  sometimes not complete

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Fungi

• cytoplasm and nuclei can stream from one cell to
  another within slender filaments of cells called
  hyphae

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Yeasts

• unicellular

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Molds

• have many cells

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Fungi

• visible to the naked eye
• mushrooms
• bracts
• puffballs
• toadstools

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Viruses

• not cellular
• particles made up of nucleic acid and protein
• Include short length of DNA or RNA - never both!

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Viruses

• On their own they cannot reproduce at all
• Inject their nucleic acid into a host cell

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Viruses

• Injected DNA or RNA tricks host cell into using
  the viruses chemical instructions to make
  substances needed for the virus to reproduce

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Viruses

• Host cell is damaged when newly reproduced virus
  particles break out of cell (lyse)

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What does it take to keep a microbe alive?

• Lots of variation in environmental and
  nutritional condition requirements

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Nutritional needs

• energy sources
• basic elements to make and replace cell structures

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Heterotrophs

• organic compounds to meet energy needs
• Carbon source to make own organic molecules
• get energy from sugars, starches, fats and other
  organic compounds

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Saprobes

• live in soil, get nutrients from dead organic
  matter
• Clostridium botulinum - botulism, food poisoning

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Autotrophs

• build their own organic compounds if they have an
  available source of inorganic compounds

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Phototrophs

• generate their own food using sunlight and
  inorganics such as carbon dioxide

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Chemotrophs

• dont require sun
• get energy from carbon dioxide, salts, water and
  others

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Nitrosomonas bacteria

• live in soil
• use ammonia (NH4) as energy

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hetero, chemo and phototrophs

• use energy from the environment
• light and heat energy from the sun
• energy stored in chemical bonds or organic or
  inorganic compounds

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Six major elements in cells

• C - Carbon
• H - Hydrogen
• N - Nitrogen
• O - Oxygen
• P - Phosphorus
• S - Sulfur

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Also -

• K- potassium
• Ca - Calcium
• Fe - Iron
• Na - Sodium

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Trace elements

• Co - Cobalt
• Zn - Zinc
• Mo - Molybdenum
• Cu - Copper
• Mn - Manganese
• Si - Silicon

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hetero, chemo, and phototrophs

• some require organic compounds that they cannot
  make themselves
• must be added to culture in isolation - called
  growth factors
• Vitamins

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Microbial nutrition in the lab

• hardened gel - called agar
• nutrients are added to the agar
• called growth medium

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Pure Cultures

• Grow only one kind of microbe
• Must use aseptic technique to avoid contaminating
  the culture

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Mixed cultures

• may be grown on selective media
• nutritious to some and not to others
• allows researchers to isolate a certain species
  of microbe

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Environmental conditions for microbial growth

• Oxygen - require Oxygen - aerobic
• some microbes live in Oxygen poor environment -
  anaerobic

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Anaerobic processes

• fermentation
• O2 atoms in compounds are rearranged and made
  available to microbes

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Anaerobes

• made up of molecules containing O2 but dont
  produce free or gaseous O2

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Anaerobes

• free oxygen may be toxic

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pH

• favorable range - 6-8
• acidophillic - acid loving used in mining
  operations.
• Oxidize Cu, Fe and other metal sulfides in the
  process of pulling out the ore

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Temperature

• 37 degrees C (98 degrees F)
• some can survive a wide range of temps ranging
  from 32 degrees F to 212 degrees F

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Moisture

• dissolve minerals, ions, gases and organic
  compounds

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Moisture

• in extremely dry conditions microbes form spores
  that hold the genetic information and some
  cytoplasm.

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Spores

• when moisture is added the spore breaks down and
  bacteria resume their normal activity

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Salt concentrations

• most microbes cant survive in high salt or sugar
  concentrations

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Microbe sex

• or - how microbes reproduce
• process is known as binary fission

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Binary fission

• increase in size, extend cell wall material down
  center and divide in two.

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Speed of reproduction

• in 24 hours some species of bacteria can go from
  one cell to 16,777,216 cells

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Single celled protists

• have a more difficult reproductive process
• DNA in nucleus is fist replicated then divided
  into 2 identical sets (mitosis)

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continued

• cytoplasm of cell then divides to form 2
  identical daughter cells.

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Fungi

• reproduce by a number of methods
• yeasts - budding - cytoplasm pinches off on one
  side of cell to form a new cell
• or fuses with another cell

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Fungi

• after fusing with a cell, nuclei fuse and divide
  to form spores when released from the cell

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Yeast

• spores become cells on their own

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Many celled fungi

• hyphae or filaments fuse to form sporagia
• cases in which nuclei from 2 parent molds
  excahange pieces of chromosomes
• a type of sexual reproduction

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Microbial populations

• can and do change over time
• bacterial populations adapt to changes in the
  environment

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Mutations

• change in DNA
• alteration of base sequence
• occur spontaneously

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Genetic recombination

• exchanging or recombining genetic information
• two bacterial cells become connected by a thin
  strand of cell material called a pilus

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Genetic recombination

• DNA can travel from one microbe to another
• gene enters a microbe that did not initially have
  it