The Microbial World

Prokaryotes Vs. Eukaryotes

Mircrobes of the Ocean

Primary ProducersAre the organisms that produce bio-mass from inorganic compounds (autotrophs). -Photosynthetic autotrophs

Phytoplankton – CyanobacteriaAlgaeDiatoms 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

Carbon dioxide

Oxygen

Aerobicrespiration

Aerobicrespiration

PRIMARY PRODUCERS

Photo-synthesizers

CyanobacteriaPhytoplanktonMulticellular algaePlants

Chemo-syntheticbacteria

Consumed byConsumed by

CONSUMERSZooplanktonAnimals

Consumed by

Nutrients released

NitrogenSulfurPhosphorus

Aerobicmetabolism Fermentation

WastesDie

Die

Anaerobicbacteria

DECOMPOSERS

Aerobic bacteriaand fungi

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

Nitrogen-fixingbacteria,cyanobacteria

2 N

+Hydrogen (H2)

Ammonia (NH3)

Dissolvednitrogen (N2)

NITROGEN FIXATION

Marineplants

Microorganisms

PhytoplanktonAlgae

NITRIFICATION

Animal wastesrecycled bymicroorganisms

Ammonium (NH4+)

Bacteria +Oxygen (O2)

Nitrite (NO2–)

Nitrate (NO3–)

Ammonia (NH3)

+Hydrogen (H2)

Bacteria +Oxygen (O2)

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

• 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

Archaea