The Microbial World Taxonomy of Chapter 5: The Microbial World Monera (Prokaryotes) Bacteria • Heterotrophic bacteria • Autotrophic bacteria • Cyanobacteria • Archaea Taxonomy of Chapter 5: The Microbial World Protista Unicellular Algae – Plant like protists • Diatoms • Dinoflagellates • Zooxanthellae • Pfiesteria • Other Unicellular Algae Taxonomy of Chapter 5: The Microbial World Protista Cont. Protozoans – Animal Like Protists • Foriminiferans • Radiolarians • Ciliates Fungi Microorganisms • Include the smallest and simplest organisms on earth • Represent all three biological domains • Are the most important primary producers in many marine environments • Directly or indirectly feed most marine animals Electron micrograph showing Cyclobacteriaum marinus, A ring forming marine bacterium. I. Prokaryotes • Simplest and smallest and oldest life forms • Carry out most all chemical processes of more complex organisms • Differ from eukaryotes in the circular DNA that encodes genetic information and size of ribosomes • All are enclosed by a cell wall in which lies a plasma or cell membrane • All lack membrane-bound organelles. Thiomargarita namibiensis, largest bacterium! Can be .03 inches wide. Round grains are sulfur granules. A. Bacteria • Structurally simple but have a great range of metabolic abilities and chemical features • Have many shapes: spheres, coils, rods, rings • Much smaller than single-celled eukaryotes • Have rigid, strong cell walls • Often covered by gelatinous material • Sometimes visible as pink or iridescent patches in stagnant pools i. Heterotrophic Bacteria • Most are decomposers (decay bacteria) and ensure the recycling of nutrients • Found throughout the water column • Feed many benthic animals • Some can degrade oil and toxic pollutants • Some spoil fish and shellfish catches ii. Autotrophic Bacteria • Are primary producers, only some are photosynthetic • Account for much of primary production in sea • Some bacteria produce sulfur instead of oxygen! • Chemosynthetic (chemoautotrophic) bacteria derive energy from H2, or H2S or NH3. iii. Cyanobacteria • “Blue-green” algae • Contain chlorophyll and phycocyanin and often phycoerythrin. • Photosynthesis occurs on folded membranes in the cell, not in chloroplasts. • Probably among the first photosynthetic organisms on earth. • Stromatolites may date back 109 years! • Many species of cyanobacteria can withstand wide ranges of salinity and temperature. Stromatolites, calcareous mounds deposited by cyanobacteria, are often found as fossils. Planktonic species may reproduce quickly and change the water color (red tide). Some cause rashes on swimmers. •Some endolithic cyanobacteria burrow into rocks and coral skeletons . Endophytes are cyanobacteria that live inside algae. Some cyanobacteria lose their ability to photosynthesize and are heterotrophs. Many carry out nitrogen fixation. Epiphytes are photosynthetic cyanobacteria that live on other plants Japanese Pufferfish store a deadly toxin, tetrodotoxin produced by a symbiotic bacteria. The fish is prepared by special chefs and many deaths occur each year in Japan (as well as suicides by disgraced chefs.) iv. Archaea • • • • Simplest, most primitive forms of life 3.8 x 109 years old!! Small, spherical, spiral or rod-shaped cells Used to be classified with bacteria, now thought to be more closely related to eukaryotes. • May be heterotrophs or autotrophs. Methanogens: methane makers, are Important decomposers. Some are N2 Fixers. Some break down material in Sewage plants. Archaea: Extremophiles • Some archaea have been found in sulfur springs, saline lakes and highly acid or alkaline environments. • Some are found in hydrothermal vents. • Some can exist at temperatures up to 235 degres Fahrenheit! • They do not depend upon extreme environments, contrary to popular opinion. II. Unicellular Algae Kingdom Protista • • • • Are mostly aquatic, mostly photosynthetic Are eukaryotic (cells contain organelles) Photosynthesis takes place in chloroplasts. Lack flowers, have simple reproductive structures. • Lack true leaves, stems and roots Some unicellular organisms that are claimed by both botanists and zoologists are classified as Protista. A. Diatoms • • • • Phylum Bacillariophyta Unicellular, may form chains or stars Enclosed by cell walls made of SiO2 (sillica) Frustule, glassy shell, is made of two halves with intricate perforations (holes) and ornaments. • Frustule allows passage of light for photosynthesis, as well as gases. • Diatoms’ color is due to carotenoid pigments and chlorophyll a and c. • Efficient photosynthetic factories • Account for major share of C and O produced on earth. • Half of all species are marine, most planktonic, but some attach. • Brown scum of mudflats or aquaria is made of diatoms. Diatom Cell • Reproduce asexually or sexually. • Fertilization results in auxospores • Blooms are periods of rapid reproduction - diatoms get smaller because they use up the silica in sea water Frustules of dead diatoms falls to the sea bed and forms siliceous material called diatomaceous ooze. - mined and used as filters in pools, for clarifying beer, as insulators and in toothpaste B. Dinoflagellates • • • • • • • Phylum Dinoflagellata Large group of planktonic, unicellular organisms Possess two flagella that direct movement Cell wall is armored with cellulose plates Most can photosynthesize Some have a light sensitive crude eye Most are marine Dinoflagellate showing the theca (cell wall) made of cellulose plates. The theca is marked by grooves for flagella. Dinoflagellate, Gonyaulax polyedra is bioluminescent and causes red tides! The Bay of Fire in Puerto Rico is filled with bioluminescence from Phrodinium bahamense, a photosynthetic dinoflagellate. They have a symbiotic relationship with mangrove trees that border the bay. i. Zooxanthellae • Golden brown photosynthetic cells that are dinoflagellates that live with an animal host. • Host may be a sponge, anemone or clam. • They fix CO2 and release organic matter used by coral to help build the coral skeleton. ii. Pfiesteria (phantom dinoflagellate) • Parasitic with life cycles that include freeswimming stages • Spends most of its life as a cyst in sediments • Blooms are triggered by coastal pollution • Pfiesteria releases powerful poisons that stun fish • Harmful to shellfish and humans – Memory loss and gastrointestinal side effects Other Unicellular Algae Dictyocha speculum, a silicoflagellate Other Unicellular Algae Umbilicosphaera sibogae, covered with calcium carbonate button called a coccolith (hence name Coccolithophorids) III. Protozoans Kingdom Protista and ?? • Structurally simple, diverse organisms that are animal like • Ingest food and are eukaryotic • Some contain chlorophyll • Most are single celled and microscopic • Placed in Protista with unicellular algae and seaweeds • Only common characteristic is their single cell! Protozoans • The single cell is considered a “super cell” which performs many of the functions carried out by cells in more complex organisms. • They live in fresh and marine environments and inside other organisms A. Foraminiferans • Marine protozoans with a shell of CaCO3. • Pseudopodia, extensions of cytoplasm, are used to trap diatoms and other food • Most live on the bottom • Shells contribute to calcareous material on coral reefs and beaches. • Shells of the few planktonic forams sink and form foraminiferan ooze (limestone and chalk beds – white cliffs of Dover) Foraminiferans with calcareous shells. Long strands are pseudopodia that capture food. On right, Homotrema Rubrum is responsible for Bermuda’s pink sand. Climate, Oil and Forams • Because the shells of warm water species are larger and more porous than cold water species, they are used to estimate ocean temperatures. • The distribution also helps determine the age of sediments and aids in finding oil. B. Radiolarians • Planktonic protozoans that secrete beautiful shells made of silica and other minerals. • Pseudopodia capture food as in forams. • Some form 3 meter long sausage shaped colonies! • Shell remains for radiolarian ooze on the sea bed. • Shells are more resistant to pressure and thus more common than forams. Radiolarian cell made of a dense central portion surrounded by a less dense zone that is involved in capturing food and buoyancy. C. Ciliates • Protozoans with hair like cilia used in locomotion and feeding. • Most common freshwater ciliate is the Paramecium. • Marine ciliates creep over seaweeds and bottom sediments. • Some live inside clams or other organisms. Tintinnids, (ciliates) form a lorica, a loosely fitting shell made of sand grains. Cilia are used in feeding. Fungi • • • • • • • • Eukaryotic , mostly multicellular Heterotrophs lacking chloroplasts 500 marine species, mostly microscopic Decomposers of dead organic matter Important in mangrove ecosystem Some are parasites that cause diseases Some live with algae to form lichens Marine lichens are seen as dark brown or black patches on rocky shores in the North Atlantic. Verruculina enalia, a marine Ascomycotina consists of black and carbonaceous fruiting bodies on branches and twigs at both low and high water marks. It is one of the most dominant marine fungi to colonise woody mangrove substrata. This is the black tar lichen. Tar lichens get their common name from the fact that they form great swathes of dark smudges on rocks, giving the rock an impression of being covered in crude oil from an oil spill.