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
Oxygen
CONSUMERS
Zooplankton
Animals
Aerobic
respiration
Consumed by
Die
Cyanobacteria
Phytoplankton
Multicellular algae
Plants
Consumed by
DECOMPOSERS
PRIMARY PRODUCERS
Photosynthesizers
Wastes
Chemosynthetic
bacteria
Die
Aerobic bacteria
and fungi
Anaerobic
bacteria
Aerobic
metabolism Fermentation
Consumed by
Nutrients released
Nitrogen
Sulfur
Phosphorus
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 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
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 (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
NITRIFICATION
NITROGEN FIXATION
Dissolved
nitrogen (N2)
Animal wastes
recycled by
microorganisms
Nitrogen-fixing
bacteria,
cyanobacteria
Ammonia (NH3)
+Hydrogen (H2)
Ammonium (NH4+)
2N
Bacteria +Oxygen (O2)
+Hydrogen (H2)
Nitrite (NO2–)
Ammonia (NH3)
Bacteria +Oxygen (O2)
Nitrate (NO3–)
Microorganisms
Marine
plants
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
Hydrothermal vents
• lipids, which help stabilize them
• under extreme conditions
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