The Microbial World

Chapter 5

Prokaryotic Metabolism

• Autotrophs• Heterotrophs

Autotrophs

• Some bacteria and archaea make their own organic compounds – Primary producers – If they do photosynthesis it takes place in on folded

membranes in the bacteria cell• Photosynthetic bacteria account for much of

the primary production of open ocean• Other bacterial autotrophs- chemosynthetic

bacteria

Heterotrophs

• Most marine bacteria are heterotrophs• Heterotrophs obtain energy from organic

matter by respiration• Respiration in aerobic bacteria and archaea

use oxygen• In Anoxic sediments bacteria use anaerobic

respiration

Nitrogen Fixation

• Bottom dwelling and planktonic cyanobacteria carry out nitrogen fixation

• Nitrogen fixation N2 NH4 (covert nitrogen to ammonium)

• Ammonium is then transferred into NO3- (nitrate) and other N compounds– These N sources can be used by primary producers

Unicellular Algae

• Algae – very diverse group (mostly aquatic, mostly photosynthetic)

• Eukaryotic- cells have a nucleus, organelles• Photosynthesis- Chloroplast• Lack true leaves, stems, roots

• Have plant and animal characteristics- Protista

Diatoms

• Unicellular but they can be colonial or form groups or chains

• In a shell made of silica frustule (2 halves) • The perforations allow dissolved gases and

nutrients to enter and exit• Coloration- carotenoid pigments (few are

colorless) • Photosynthetic factories• Some are toxic

Diatom Reproduction

• Asexual reproduction• Auxospores- resistant stages that eventually

give rise to larger cells that display the frustule characteristic of the species **get smaller each division**

• Favorable conditions- bloom• Diatomaceous ooze- dead diatoms sink and

form thick deposits of siliceous material

Dinoflagellates

• Large group of planktonic unicellular organisms

• 2 flagella, cell wall, plates• Photosynthesize and ingest • Reproduction is almost exclusively by cell

division• Bioluminescence • Toxic

Protozoans (animal like protists)

• Eukaryotic • Structure is simple• Animal like• Protozoans comprise several groups of

unrelated origins• Heterotrophs and some photosynthesize

Foraminiferans

• Type of marine protozoan• Have a shell (test) made of CaCO3• Pseudopodia- extensions of the cytoplasm• Live on the bottom either free or attached– Shells of bottom forams are important

contributors to calcarious material• White cliffs of Dover

Radiolarians

• Planktonic marine protozoans• Secrete shells of glass and other materials • Typical shells are spherical with radiating

spines • Sausage shaped colonies• When they die and sink to the bottom they

become silicious ooze – Resistant to dissolving under pressure

Ciliates

• Protozoans • Lots of hair like extentions– Locomotion and feeding

• Found all over seaweeds and in bottom sediments

• Live in gills of clams, urchin intestines,skin of fish

Fungi

• Eukaryotic and mostly multicellular– Molds, yeasts are unicellular

• They are heterotrophs that lack chloroplasts• 500 species of marine fungi (most are microscopic)• Decompose detritus• Some are parasites• Some form symbiotic relationships with algae – lichens

Microbial world

Prokaryotes• Bacteria

– Cyanobacteria (stromatolites)• Archaea

– Extremophiles

Eukaryotes• Diatoms• Dinoflagellates• Protozoans (animal like)

– Foraminierans– Radiolarians

• Fungi

Presentation

• Table 1 –Diatoms• Table 2- Dinoflagellates• Table 3- Foraminiferans• Table 4- Radiolarians• Table 5- Ciliates• Table 6- Fungi

Poster Rubric• Image• Definition• At least 5 facts • Importance to marine environment/role in marine

environment

• ** this will be a graded assignment**

• If you finish early complete your sponge reading and question sheet until we start presenting