Transcript Document

Opener
The
Microbial
World
Radiolarian shells
1
Microorganisms
The most abundant forms of marine life.
 Represented in all three biological
domains.


Bacteria, Archaea, Eukarya
Smallest and structurally simplest
 Primary producers


Organisms that manufacture organic matter
from CO2, usually by photosynthesis.
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Fig. 5.1
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Viruses
Not made up of a cell
 Short chain of genetic
material (nucleic acid)
 Relatively few genes
 Protected by capsid, outer protein
coat
 Parasites
 20 to 200 nm in size

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Retroviruses
Genetic information stored as RNA
 Responsible for human diseases

HIV/AIDS
 leukemia

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Lytic and Lysogenic viruses
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Lysogenic viruses


Reproduce by inducing their nucleic acid
to become part of the genome of the host
cell.
Genome then directs the production of
new viruses.
LYTIC VIRUSES infects cells,causing them
to burst
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Bacteriophages
Viruses that specifically target and
destroy bacteria.
 Common in marine environments

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Viruses and algae
Viruses infect phytoplankton
 Bursting releases DOM (dissolved
organic matter)

DOM not used by most organisms
 DOM is taken up by bacteria and
microbes

• in turn, they’re eaten by zooplankton
• in turn, they’re eaten by larger zooplankton

Bursting releases essential nutrients
• used by primary producers
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Viral diseases
Shellfish
 Fishes
 Sea turtles
 Marine mammals
 Humans


oysters and mussels filter sewagecontaminated water.
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Prokaryotes
Smallest, structurally simplest living
organisms
 oldest forms of life on earth
 most chemical processes evolved
first in prokaryotes

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Prokaryotic cells
protective cell wall
 plasma membrane immediately
inside cell wall
 lack a nucleus
 lack most membrane-bound
organelles
 circular DNA

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Fig. 5.2
Cyclobacterium marinarus, a ringforming marine bacterium
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Fig. 5.3
The largest known
bacterium,
Thiomargarita
namibiensis, 0.75mm
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2 prokaryotic domains
 Bacteria

and Archaea
Differences in:
• chemistry of cell walls
• cell membranes
• cellular machinery that makes proteins
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Bacteria
Many shapes: spheres, rods, spirals,
rings
Rigid and strong cell walls
Stiff or slimy covering




protection or attachment
Very small



from about 0.1 to about 600 µm
from just bigger than a virus, to nearly
visible
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Ubiquitous bacteria

Bacteria are ubiquitous, that is, they
occur EVERYWHERE in the ocean.
all surfaces
 water column
 most abundant life form in the open
ocean
 300 m deep in buried sediment

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Bacteria as Decomposers
Grow in detritus (dead organic
matter)
 break down waste products
 release nutrients back into the
environment
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Cyanobacteria
formerly called blue-green algae
 photosynthetic
 pigments

chlorophyll a (like eukaryotes)
 phycocyanin (blue)
 phycoerythrin (red)

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cyanobacteria, continued


role in accumulating O2 in the early
atmosphere
fossil stromatolites




calcareous mounds (made of CaCO3)
oldest are 3 billion years old
still being formed
Prochlorococcus – most abundant
photosynthetic organism in the ocean
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Fig. 5.4
stromatolites in the
Bahamas
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Types of cyanobacteria
endolithic – burrow into calcareous
rocks and coral skeletons
 Planktonic species rapidly multiply


some “red tides”
epiphytes live on algae
 endophytes live in algae

lifeinfreshwaterorg.uk
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Archaea, page 1
 among
simplest, most primitive
 Oldest fossils: 3.8 billions years
old
 common in water column and
sediments
 Important role in early evolution
 Spherical, spiral, rod shaped
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Fig. 5.5
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Archaea, page 2

some are “extremophiles”
Deep water: high pressure (300-800
atm)
 hypersalinity
 high temperatures (70-80oC)

• some up to 121oC


extreme pH (acid and alkaline)
some live symbiotically in sponges,
seacucumbers, and fishes
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Page 92
Depth distribution of
bacteria and archaea in
the subtropical North
Pacific
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Prokaryote metabolism



metabolism –all the chemical reactions that
take place in an organism
autotrophs – organisms that can use energy
to make their own organic compounds
(primary producers)
photoautotrophs – photosynthetic, contain
chlorophyll and photosynthetic pigments to
trap light energy



Use CO2 to make organic compounds
release O2
not the same process as in plants
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Light energy without
photosynthesis

Light-mediated ATP synthesis
energy from sunlight trapped in ATP
 proteorhodopsin, bacteriorhodopsin

• pigment converts light energy to ATP
• doesn’t use cholorphyll
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Chemosynthesis

Deriving energy from chemical
compounds
hydrogen sulfide (H2S)
 oxidation reactions

• substrates: ammonium, nitrite, iron
• oxidation reactions add oxygen or remove
hydrogen forming higher energy bonds
• chemical energy is stored in chemical
bonds
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Tab. 5.1
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Heterotrophs

obtain energy from organic matter by
respiration
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
in marine bacteria and archaea: mostly
decomposers
respiration in aerobic bacteria uses oxygen
respiration in anaerobic bacteria does not use
oxygen
• anaerobic bacteria won’t grow in the presence of
oxygen
• anoxic (devoid of oxygen ) sediment is site of H2S
producing bacteria
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Nitrogen fixation
conversion of gaseous nitrogen (N2)
into ammonium(NH4+1)
 ammonium can be used as a
nitrogen source for primary
producers
 carried out by planktonic
cyanobacteria
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Protista
simple eukaryotes
 unicellular or multicellular without
specialized tissues
 formerly a kingdom


relatively simple organization
• distinguishes the protists from other
eukaryotes, such as fungi, animals and
plants.
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Unicellular algae

photosynthesis takes
place in chloroplasts
green, red, brown organelles
 layers of internal membranes with
pigments
 “plants”
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• no flowers, leaves, stems, or roots
• some swim with flagella
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Diatoms

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Phylum Bacillariophyta
unicellular (may aggregate into chains or
stars)
open water primary producers
cell walls made of silica (SiO2)
glassy shell called frustule

golden brown chloroplasts
• chlorophyll a and c, carotenoid pigments

minute perforations
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Domoic acid

Some diatoms produce domoic acid
neurotoxin
 contaminates fish or shellfish
 fatal to marine mammals and humans
that eat contaminated organisms

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Fig. 5.6
Diatom cell
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Fig. 5.7
Diatom reproduction
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Dead diatoms

settle to the ocean floor
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form biogenous sediments
• siliceous ooze
• diatomaceous ooze
• fossil deposits found inland make
diatomaceous earth
• used in pool filters
• insulators
• mild abrasives
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Blooms
Rapid reproduction
 Triggered by favorable
environmental conditions
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
nutrients and light
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Fig. 5.8
DINOFLAGELLATES
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Dinoflagellates
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Unicellular
Planktonic
Cell wall made of cellulose
Most photosynthesize
Some ingest food particles
Crude eye (light sensitive pigment spot)
One of the major causes of “red tide”
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Zooxanthellae
round, golden-brown dinoflagellates
 live in association with animals

sponges
 giant clams
 sea anemones


Help provide organic matter to coral
for reef building
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Fig. 5.9
Silicoflagellate
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Fig. 5.10
Coccolithophorids,
Umbilicosphaera sibogae
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Protozoans
animal-like eukaryotes
 unicellular
 heterotrophic (ingest food)
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Foraminiferans
Phylum Granuloreticulosa
 Marine protozoans
 shell, or test, made of calcium
carbonate (CaCO3)
 retractable pseudopodia
 live on sea bottom, form
foraminiferous ooze
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Fig. 5.11
foraminiferans
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Fig. 5.12
radiolarians –
shells made of
glass
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Ciliates

Protozoans with hairlike cilia
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Fig. 5.13
Tintinnopsis
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Fungi
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Eukaryotic
molds and yeasts
multicellular
live symbiotically with algae to form
lichen
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

fungi support
algae or cyanobacteria provide food from
photosynthesis
1500 known marine species
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Fig. 5.14
Encrusting lichens form
a dark band.
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Page 90
Japanese pufferfish, fugu
Do symbiotic bacteria produce tetrodotoxin?
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Page 96
Bioluminscent dinoflagellates
Phosphorescent bay, Puerto Rico
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Tab. 5.2
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