Download Chapter 5 Viruses Viruses Prokaryotes Prokaryotes Prokaryotes

Viruses
• NonNon-cellular infectious agents that have
two basic characteristics:
Chapter 5
The Microbial World
Viruses
• Viruses in the Marine Community:
– They are common in marine waters
– They can infect bacteria, plankton, fish, sea
turtles and marine mammals
– Lysis (bursting) of viral infected cells spills
contents and releases large amounts of
organic matter that can be utilized by other
organisms (dissolved organic matter or DOM)
– Not capable of reproduction without a host
cell
– Structure:
• Nucleic acid corecore- can be DNA or RNA
• Capsid (Protein coat)coat)- consists of numerous protein subunits
organized into rodrod-like or many sided shape. Protein coat
also contains specific proteins that bind with receptors on
host cells (great at mimicry!!) Many glycoprotein spikes
extend from coatcoat-these spikes mutate so frequently that our
immune system cannot keep up.
Prokaryotes
• Archea and Bacteria
• Characteristics of Archean and Bacterial Cells:
– ProkaryoticProkaryotic- no nucleus
– Single chromosome (normally circular)circular)- some also
with plasmids
– Most with cell wall
– Great metabolic diversity
Prokaryotes
Prokaryotes
• Archea –
– Ancient organisms – fossils found that date
back 3.8 billion years
– Some live in very extreme environments
– Variety of metabolic types
– Widely distributed in the marine community
– They can tolerate wide ranges in temperature,
salinity and even desiccation (drying out)
– Can be found in many areas including near
hydrothermal vents and salt flats (two very
extreme environments)
• Special Features of Bacteria:
• A variety of shapes including spirals,
spheres, rods and rings
• Cell wall structure is semisemi-rigid, but
permeable; most with cell wall
• Size is normally microscopic, but a few are
large
• Wide variety of metabolic types
• Very abundant worldwide
Aerobic respiration
Prokaryotes
• Metabolic diversity:
• Photosynthesis – derive energy from light
• Chemosynthetic – derive energy from
chemical compounds
• Heterotrophs – derive energy from organic
matter by respiration
Prokaryote metabolic diversity
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•
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Dissolved organic carbon in the
ocean
• Forms polymers and particles (snow) that
are the habitat for many prokaryotes in the
water column
Heterotrophic microbial metabolism
Fermentation
Special metabolic properties
– Methylotrophy
– Syntrophy
Anaerobic respiration
– Denitrification - nitrate as electron acceptor
– Sulfate reduction - sulfate as electron acceptor
• Electron donors
• Energy for reduction
– Acetogenesis - carbon dioxide as electron acceptor
– Other inorganic electron acceptors
– Organic terminal electron acceptors
Chemolithotrophy
– Hydrogen oxidation
– Sulfur oxidation
– Ferrous iron (Fe2+) oxidation
– Nitrification
– Anammox
Phototrophy
Carbon in the ocean (gigatons)
organisms
dissolved organic
surface ocean
deep ocean
sediment
3
700
1020
38100
150
39973
Transparent exopolymers
Transparent
exopolysaccharides(TEP)
• Recall that there are 700 gigatons of
dissolved organic compounds in the ocean
Marine snow
Phytoplankton
• Unicellular algae and cyanobacterial
component of the plankton
• 50% of global photosynthesis
• Some major algal groups
– Diatoms
– Dinoflagellates
– coccolithophores
Global primary production
Diatoms
• Diatoms:
– Photosynthetic
– YellowYellow-brown color in life is a result of
photosynthetic pigments, chlorophyll A and C
and carotenoids
– Shell of silica called a frustule
– Most important primary producer on Earth
– Mostly solitary and unicellular
– Some can form colonies
Diatoms
• Diatoms
– Around half of the 12, 000 known species are marine
– Most are planktonic
– Store excess energy as an oil which also aids in
buoyancy
– Tiny pores in shell used for gas/nutrient exchange
Dinoflagellates
• Dinoflagellates
–
–
–
Most species live in marine environment
Mostly photosynthetic, some can ingest particles
Each species has unique shape reinforced by plates
of polysaccharide (like cellulose)
– Two flagella in grooves on body that produce motion
– Some are bioluminescent (read “Bay of Fire”
Fire” on pg.
96)
•
Ceratium-dinoflagellates
Dinoflagellates occur in enormous numbers in the ocean, particularly in tropical
waters and display a huge diversity of form. The large protrusions seen on this
Ceratium-dinoflagellate are used for protection against predators.
Dinoflagellates
• Dinoflagellates
– Zooxanthellae are important dinoflagellates
that live in a symbiotic relationship with corals,
sea anemones and other organisms (many of
these host organisms have little or no growth
without their symbiotic partner)
Algal bloom southern England
Red tides - dinoflagellates
Algal Blooms
• Diatoms and dinoflagellates can go
through periods of rapid growth known as
“blooms”
blooms”
• This is a result of high levels of nutrients in
the water
• These blooms can be harmful to marine
organisms and even people at times
Coccolithophore bloom Bering Sea
Dinoflagellates
– A few species lack chloroplasts and live as parasites
in marine organisms
– Some species can reproduce in larger numbers and
produce “Red Tide”
Tide” (read “Red Tides and Harmful
Algal Blooms, pg. 338)
– Pfiesteria is a dinoflagellate that produces very
serious toxins that can cause massive fish kills, harm
shellfish and impair the nervous system in humans.
– Pfiesteria was discovered near the Outer Banks in
North Carolina
– Coccolithophores
• Ornate shells of calcium carbonate
Protozoa
• Foraminiferans (forams)
– Exclusively found in marine community
– Found on sandy or rocky bottoms
– Shells of calcium carbonate
– Can be important contributors of calcareous
material on coral reefs or sandy beaches
– Pseudopods (false feet) extend through pores
in the shell where they are used to capture
minute food particles such as phytoplankton
Protozoa
• Radiolarians
– Planktonic, mostly microscopic, although a
few can reach large sizes
– Shell of silica
– Like forams, they use pseudopods that extend
through pores in the shell where they are
used to capture minute food particles such as
phytoplankton
Protozoa
• Ciliates
– Cilia present for locomotion
– Most live as solitary cells
– Some build shells made of organic
debris
– May live on hard substrate
– Some are planktonic
Fungi
• Eukaryotic and mostly multicellular
• Heterotrophic
• Most of the 1500 species of marine fungi
are microscopic
Fungi
• Like bacteria, many fungus break down
dead organic matter into detritus
• Some fungus live in symbiosis with
cyanobacteria, these are known as lichens
• Marine lichens often live in wavewave-splashed
areas of rocky shorelines and other hard
substrate