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Marine Microbes

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Chapter 6 Marine Microbes – PowerPoint PPT presentation

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Title: Marine Microbes


1
Chapter 6 Marine Microbes
2
Key Concepts
  • Microbial life in the sea is extremely diverse,
    including members of all three domains of life as
    well as viruses.

3
Key Concepts
  • Photosynthetic and chemosynthetic bacteria are
    important primary producers in marine ecosystems.
  • Heterotrophic bacteria, and fungi play essential
    roles in recycling nutrients in the marine
    environment.

4
Key Concepts
  • Some Marine microbes contribute significantly to
    the accumulation of deep-sea sediments.
  • Populations of several kinds of photosynthetic
    marine microbes may form harmful blooms that
    affect other marine and maritime organisms
    directly and indirectly.

5
Marine Viruses
  • Virologythe study of viruses
  • Viruses are diverse and are more abundant than
    any other organism in the sea
  • Have significance for marine food webs,
    population biology and diseases of marine
    organisms

6
Ecology of Marine Viruses
  • Viruses kill host cells, and thus control
    populations of bacteria and other microbes in
    plankton communities
  • Viruses also responsible for chronic infection
    and mass mortality of populations of marine
    animals

7
Marine Bacteria
  • General characteristics
  • simple, prokaryotic organization no nuclei or
    membrane-bound organelles, few genes
  • reproduce asexually by binary fission
  • many shapes and sizes
  • bacillusrod shape
  • coccusspherical shape

8
Nutritional Types
  • Cyanobacteria (blue-green bacteria)
  • photosynthetic bacteria which are found in
    environments high in dissolved oxygen, and
    produce free oxygen
  • primary photosynthetic pigments are chlorophyll a
    and chlorophyll b

9
Nutritional Types
  • Chemosynthetic bacteria
  • use energy derived from chemical reactions that
    involve substances such as ammonium ion, sulfides
    and elemental sulfur, nitrites, hydrogen, and
    ferrous ion
  • chemosynthesis is less efficient than
    photosynthesis, so rates of cell growth and
    division are slower
  • found around hydrothermal vents and some
    shallower habitats where needed materials are
    available in abundance

10
Stepped Art
Magma (molten rock)
Fig. 6-10, p. 134
11
Nutritional Types
  • Heterotrophic bacteria
  • decomposers that obtain energy and materials from
    organic matter in their surroundings
  • return many chemicals to the marine environment
    through respiration and fermentation

12
Nutritional Types (Heterotrophic Bacteria)
  • Heterotrophic bacteria
  • marine snow large, cobweb-like drifting
    structures formed by mucus secreted by many kinds
    of plankton, where particles may accumulate

13
Symbiotic Bacteria
  • Many bacteria have evolved symbiotic
    relationships with a variety of marine organisms
  • Chemosynthetic bacteria live within tube worms
    and clams
  • Some deep-sea or nocturnal animals host helpful
    bioluminescent bacteria
  • photophores
  • embedded in the ink sacs of squid

14
Archaea
  • General characteristics
  • small (0.1 to 15 micrometers)
  • prokaryotic
  • adapted to extreme environmental conditions high
    and low temperatures, high salinities, low pH,
    and high pressure
  • differences from bacteria
  • cell walls lack special sugar-amino acid
    compounds in bacterial cell walls
  • cell membranes contain different lipids, which
    help stabilize them under extreme conditions

15
Archaea
  • Nutritional Types
  • photosynthesizers, chemosynthesizers and
    heterotrophs
  • most are methanogens anaerobic organisms that
    metabolize organic matter for energy, producing
    methane as a waste product
  • halobacteria thrive at high salinities

16
Archaea
  • Hyperthermophiles
  • organisms that can survive at temperatures
    exceeding 100o C, such as near deep-sea vents
  • Potential for biomedical and industrial
    application

17
Eukarya
  • Eukarya includes all organisms with eukaryotic
    cells
  • Examples
  • plants
  • animals
  • fungi
  • algae
  • single-celled animal-like protozoa

18
Fungi
  • important in marine ecosystems as decomposers,
    prey, pathogens and symbionts

19
Fungi
  • General features of fungi
  • heterotrohic decomposers that recycle organic
    material
  • can digest lignin (major component of wood)

20
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21
Fungi
  • Ecology and physiology of marine fungi
  • salinity is toxic to fungi, so they must devote
    energy to removing sodium
  • most marine fungi live on wood from land
  • some live on grass in salt marshes
  • others live on algae, mangroves or sand

22
Maritime Lichens
  • Lichens mutualistic associations between a
    fungus and an alga
  • algae are usually green or blue-green bacteria
  • The fungus provides attachment, general
    structure, minerals, moisture
  • The alga produces organic matter through
    photosynthesis

23
Diatoms
  • Diatom structure
  • 2 basic diatom shapes
  • radially symmetrical valves (generally
    planktonic)
  • bilaterally symmetrical valves (generally benthic)

24
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25
Diatoms
  • Diatomaceous sediments
  • frustules of dead diatoms sink and collect on the
    seafloor to form siliceous oozes
  • accumulations form sedimentary rock
  • these deposits, called diatomaceous earth, are
    mined for use as filtering material, a mild
    abrasive, and for soundproofing and insulation
    products
  • nutrient reserves, stored as lipids, accumulate
    in siliceous oozes accounting for most of the
    worlds petroleum reserves

26
Alveolates
  • Dinoflagellates
  • globular, unicellular (sometimes colonial) with 2
    flagella
  • Most are planktonic, some are benthic and others
    parasitic, also can be bioluminescent
    Bioluminescent Bay, Puerto Rico

27
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28
Alveolates (Dinoflagellates)
  • Dinoflagellate structure
  • simple flagellum encircles the cell in the
    horizontal groove and produces a spinning motion
  • longer flagellum with hair-like filaments trails
    down the longitudinal groove and imparts most of
    the forward motion to the cell
  • number, size and shapes of plates are used to
    identify different species

29
Alveolates (Dinoflagellates)
  • Ecological roles of dinoflagellates
  • major component of phytoplankton
  • some are parasites of copepods (crustaceans)
  • zooxanthellae species lacking flagella which are
    symbionts of jellyfish, corals and molluscs
  • photosynthetic zooxanthellae provide food for
    hosts
  • hosts provide carbon dioxide, other nutrients,
    and shelter

30
Alveolates (Dinoflagellates)
  • Harmful Algal Blooms (HABs)
  • occur when photosynthetic dinoflagellates undergo
    a population explosion
  • colors the water red, orange or brown
  • dinoflagellates that cause HABs produce toxins
  • paralytic shellfish poisoning (PSP) occurs in
    humans who consume shellfish contaminated with
    these toxins
  • toxins cannot be destroyed by cooking
  • oxygen content of the water may be reduced to
    deadly levels as bacteria decompose animals
    killed by dinoflagellate toxins
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