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 H2S & CH4 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

Aerobic respiration Aerobic metabolism Oxygen Aerobic respiration Consumed by CONSUMERS Zooplankton Animals Carbon dioxide Wastes Die Anaerobic bacteria DECOMPOSERS Aerobic bacteria and fungi PRIMARY PRODUCERS Photo-synthesizers Cyanobacteria Phytoplankton Multicellular algae Plants Chemo-synthetic bacteria Consumed by Nutrients released Nitrogen Sulfur Phosphorus Aerobic metabolism Fermentation 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 O2) and anaerobic (without O2) environments reproduce asexually by binary fission many shapes and sizes bacillus—rod shape coccus—spherical shape Spirillum – cork screw shape

Bacteria Bacteria usually have one of three different cell shapes Coccus (Sphere-shaped) Ex: Streptococcus Bacilli (rod-shaped) Ex: Lactobacillus Spirillum (Spiral-shaped) 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 (NH4+) to nitrite (NO2-) and nitrate (NO3-) ions bacterial nitrification converts ammonium into a form of nitrogen usable by other primary producers (autotrophs) Nitrosomonas and Nitrobacter

Marine plants Phytoplankton Algae NITROGEN FIXATION NITRIFICATION Nitrogen-fixing bacteria, cyanobacteria 2 N +Hydrogen (H2) Ammonia (NH3) Dissolved nitrogen (N2) Animal wastes recycled by microorganisms Ammonium (NH4+) Bacteria +Oxygen (O2) Nitrite (NO2–) Nitrate (NO3–) Ammonia (NH3) +Hydrogen (H2) Marine plants Microorganisms Phytoplankton Algae 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

Archaea General characteristics small (0.1 to 15 micrometers) prokaryotic 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 100o C, such as near deep-sea vents Potential for biomedical and industrial application