BIO 475 Lecture 19: Coral Microbiology & Disease
● Microbes, especially the picoplankton, microbial plankton with sizes ranging from 0.2 to
2.0 microns, are as important as the traditional marine food web.
● Bacteria
○ No membrane enclosed organelles or nuclei
○ No cytoskeleton
○ Some use chlorophyll-based photosynthesis
○ Extremely diverse (1-3 million estimated species)
○ Estimated to originate 2 million years before giving rise to eukaryotes
● Eukarya (Protista)
○ Membrane enclosed organelles
○ Membrane enclosed nuclei
○ Contain a cytoskeleton (network of fibrous proteins)
○ Ex. Dinoflagellates, ciliates, coccolithorphora,etc
■ Dinoflagellates
● Two, hair-like flagella used to swim through the water
● ~½ are photosynthetic
● Dominate regions of low turbulence and nutrients
● Range from 30 microns - 2mm
● Ex. Zooxanthellae
■ Ciliates
● Filter feeders
● Have hundreds of cilia around the central opening
○ Locomotion and feeding
● Ex. Paramecium
■ Coccolithophora
● Small organisms with two smooth flagella
● Covered by calcareous plates called coccoliths
● Dominate in regions of moderate turbulence and nutrients
● Size is 5-10mm in diameter
● 15% of oceanic phytoplankton biomass; important on global scale
● Archaea
○ A.K.A extremophiles
○ Aerobic and Anaerobic
○ Largely methane producing
○ No membrane enclosed organelles or nuclei
○ No cytoskeleton
○ NONE use chlorophyll based photosynthesis
○ Can live at extreme depth, in extreme temperatures, salinities, acidity etc
■ Extremophiles
● Viruses
○ Oceans contain ~ 4x1030 viruses
○ Attack and kill archaea bacteria and other microorganisms
○ Can manipulate the evolution of other microbial life
■ Transfer genetic material back and forth
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● Kill cell, or transfer genetic material to that cell from previous host
( horizontal gene transfer) or can transfer own genome (
accessory gene transfer)
● Can allow cell to expand and exploit a new niche
○ Initiate activation of photosynthetic gene allowing
organisms so be able to photosynthesize
● Can pocket genetic information from host and keep them in GTA’s
○ Can use GTA to do horizontal gene transfer
○ Marine viruses and viral-like entities, including eukaryotic viruses, phage and
generalized transfer agents (GTAs), can have various effects on host cells
○ Chesire cat hypothesis
■ Any host; the phage tries to infect cell and it will actually transition from
being non-model and diploid to haploid and model ( revert to haploid and
swim away to avoid infection)
■ Alternative affect; the host and the virus can undergo evolutionary arms
race, both trying to mount resistance against one another
● Generally virus will win because it can evolve more rapidly
● Color Holobiont
○ The host organism and ALL of its associated symbiotic microorganisms
■ Protist
■ Zooxanthellae
■ Viruses, Bacteria, & Archaea
■ Endolithic algae
● Holobiont
○ Three habitats for bacteria
■ Surface mucus layer
■ Coral Tissues
■ Skeleton
○ Micro-niches within each habitat
○ Species composition changes among habitats and micro-niches
● Coral-associated Microbial Diversity
○ Bacterial abundance in coral mucus is 100-1000 times higher than that observed
in seawater (106 per ml in coral vs. 103 per ml in sw)
○ Level of control of which bacteria are residing in coral host and where
● How do corals acquire bacteria?
○ From the environment
○ Passive transport
■ Across cell membranes
○ Active transport
■ Consumption
○ Post-metamorphosis
■ (Sharp et al. 2010)
■ Done on broadcasting corals 1st, then porites astreoides(brooding) 2nd
● Brooding transferred bacteria right to polyps
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Microbes, especially the picoplankton, microbial plankton with sizes ranging from 0. 2 to. 2. 0 microns, are as important as the traditional marine food web. Estimated to originate 2 million years before giving rise to eukaryotes. Contain a cytoskeleton (network of fibrous proteins) Two, hair-like flagella used to swim through the water. Dominate regions of low turbulence and nutrients. Have hundreds of cilia around the central opening. Dominate in regions of moderate turbulence and nutrients. 15% of oceanic phytoplankton biomass; important on global scale. Can live at extreme depth, in extreme temperatures, salinities, acidity etc. Attack and kill archaea bacteria and other microorganisms. Can manipulate the evolution of other microbial life. Kill cell, or transfer genetic material to that cell from previous host ( horizontal gene transfer) or can transfer own genome ( accessory gene transfer) Can allow cell to expand and exploit a new niche. Initiate activation of photosynthetic gene allowing organisms so be able to photosynthesize.
