The Microbial World
Prokaryotes Vs. Eukaryotes
Mircrobes of the Ocean
Primary Producers Are the organisms that produce bio-mass from inorganic compounds (autotrophs). -Photosynthetic autotrophs Phytoplankton Cyanobacteria Algae Diatoms Dinoflagellates Plants -Chemosynthetic autotrophs release energy from chemical compounds such as H 2 S & CH 4 Archaea (Hydrothermal vents) Bacteria nitrosomonas and nitrobacter -Heterotrophs energy from organic matter by respiration Decomposers Bacteria Fungi
Phytoplankton photosynthesizing microscopic organisms (autotrophs) that inhabit the upper sunlit layer of almost all oceans and bodies of fresh water They form the base of the ocean food chain. phytoplankton are a diverse group, incorporating protists eukaryotes and both bacterial and archaebacteria prokaryotes
Oxygen Aerobic respiration CONSUMERS Zooplankton Animals Aerobic respiration Consumed by Die Wastes Consumed by PRIMARY PRODUCERS DECOMPOSERS Cyanobacteria Phytoplankton Multicellular algae Plants Photosynthesizers Chemosynthetic bacteria Die Aerobic bacteria and fungi Anaerobic bacteria Consumed by Nutrients released Nitrogen Sulfur Phosphorus Aerobic metabolism Fermentation Carbon dioxide Stepped Art Fig. 6-6, p. 131
Bacteria General characteristics simple, prokaryotic organization: no nucleus or membrane-bound organelles, few genes, cell wall Can live in both aerobic (with O 2 ) and anaerobic (without O 2 ) environments reproduce asexually by binary fission many shapes and sizes bacillus rod shape coccus spherical shape Spirillum cork screw shape
Bacteria Ex: Streptococcus Ex: Lactobacillus Ex: Spirillium
Cyanobacteria (blue-green bacteria) Photosynthetic bacteria which are found in environments high in dissolved oxygen, and produce free oxygen Usually found in low depths of ocean Contain chlorophyll a and b First photosynthetic organisms on earth
Cyanobacteria Form associates called stromatolites a coral-like mound of microbes that trap sediment and precipitate minerals in shallow tropical seas 3.2 billion years old
Algal Blooms algal bloom (large concentrations of aquatic microorganisms usually phytoplankton) Caused by cyanobacteria or dinoflagellates that are often green, but they can also be other colors such as yellow-brown or red high concentrations Can produce some of the most powerful toxins known harmful algal blooms (HABs), which are red tides caused by the Protist Dinoflagellates or Diatoms» Mass killings the production of neurotoxins which cause mass mortalities in fish, seabirds, sea turtles, and marine mammals» human illness or death via consumption of seafood contaminated by toxic algae
Algal Blooms algal bloom (large concentrations of aquatic microorganisms usually phytoplankton) Caused by cyanobacteria or dinoflagellates that are often green, but they can also be other colors such as yellow-brown or red high concentrations Can produce some of the most powerful toxins known harmful algal blooms (HABs), which are red tides caused by the Protist Dinoflagellates or Diatoms» Mass killings the production of neurotoxins which cause mass mortalities in fish, seabirds, sea turtles, and marine mammals» human illness or death via consumption of seafood contaminated by toxic algae
Red Tides
Nitrogen Fixation Nitrogen fixation: process that converts molecular nitrogen dissolved in seawater to ammonium ion major process that adds new usable nitrogen to the sea only some cyanobacteria and a few archaeons with nitrogenase (enzyme) are capable of fixing nitrogen
Nitrification Nitrification: process of bacterial conversion of ammonium (NH 4+ ) to nitrite (NO 2- ) and nitrate (NO 3- ) ions bacterial nitrification converts ammonium into a form of nitrogen usable by other primary producers (autotrophs) Nitrosomonas and Nitrobacter
NITROGEN FIXATION NITRIFICATION Dissolved nitrogen (N 2 ) Animal wastes recycled by microorganisms Nitrogen-fixing bacteria, cyanobacteria Ammonia (NH 3 ) +Hydrogen (H 2 ) 2 N +Hydrogen (H 2 ) Ammonia (NH 3 ) Ammonium (NH 4+ ) Bacteria +Oxygen (O 2 ) Nitrite (NO 2 ) Bacteria +Oxygen (O 2 ) Marine plants Microorganisms Phytoplankton Algae Nitrate (NO 3 ) Stepped Art Fig. 6-11, p. 135
Other photosynthetic bacteria anaerobic green and purple sulfur and non-sulfur bacteria do not produce oxygen the primary photosynthetic pigments are bacteriochlorophylls sulfur bacteria are obligate anaerobes (tolerating no oxygen) non-sulfur bacteria are facultative anaerobes (respiring when in low oxygen or in the dark and photosynthesizing anaerobically when in the presence of light)
Heterotrophic bacteria decomposers that obtain energy and materials from organic matter in their surroundings return many chemicals to the marine environment through respiration and fermentation Aerobic Respiration Organic matter + O2 ---> CO2 + H2O + chemical energy Anaerobic Respiration Organic matter + H+ ---> CH4 + chemical energy
Symbiotic Bacteria Many bacteria have evolved symbiotic relationships with a variety of marine organisms Endosymbiotic theory Mitochondria and chloroplasts evolved as symbionts within other cells Chemosynthetic bacteria live within tube worms and clams Some deep-sea or nocturnal animals host helpful bioluminescent bacteria photophores embedded in the ink sacs of squid
Symbiotic Bacteria Anglerfish have light emitting symbiotic bacteria in dorsal appendage
General characteristics small (0.1 to 15 micrometers) prokaryotic Archaea adapted to extreme environmental conditions: high and low temperatures, high salinities, low ph, and high pressure formerly considered bacteria differences from bacteria cell walls lack special sugar-amino acid compounds in bacterial cell walls cell membranes contain different lipids, which help stabilize them under extreme conditions Hydrothermal vents
Archaea Nutritional Types archaea includes photosynthesizers, chemosynthesizers and heterotrophs most are methanogens: anaerobic organisms that metabolize organic matter for energy, producing methane as a waste product halobacteria (photosynthetic), thrive at high salinities Hyperthermophiles organisms that can survive at temperatures exceeding 100 o C, such as near deep-sea vents Potential for biomedical and industrial application