Diversity of Prokaryotic Organisms
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Transcript Diversity of Prokaryotic Organisms
The Diversity of
Prokaryotic Organisms
Chapter 11
Anaerobic Chemotrophs
Found in soil, aquatic environments and the
human body
Organisms in this classification
Anaerobic chemolithotrophs
Anaerobic chemoorganotrophs
Anaerobic Chemotrophs
Chemolithotrophs oxidize reduced inorganic
chemicals to produce energy
Use alternate terminal electron acceptor other
that oxygen
Usually carbon dioxide or sulfur
Usually members of the domain Archaea
Anaerobic Chemotrophs
Methanogens
Members of Domain Archaea
Produce energy by reducing
hydrogen and using carbon
dioxide as terminal electron
acceptor(4H2 + CO2 CH4 + 2H2O)
This process creates
methane and water
Commonly found in sewage,
swamps marine sediments and
digestive tract of mammals
Highly sensitive to oxygen
Anaerobic chambers used for
cultivation
Anaerobic Chemotrophs
Some anaerobic chemoorganotrophs produce
ATP via anaerobic respiration through the
oxidation of organic molecules
Also use terminal electron acceptor other than
oxygen
Sulfur and sulfate are common
Other anaerobic chemoorganotrophs produce
energy through fermentation
Produce energy through substrate
phosphorylation only
Anaerobic Chemotrophs
Sulfur and sulfate-reducing bacteria use
sulfur as terminal electron acceptors and
oxidize organic material
Reducing it to hydrogen sulfide
Responsible for rotten egg smell
These organisms essential for sulfur cycle in
ecosystem
Generally found in mud rich in organic matter
and sulfur
Yellowstone Mud Geyser
Yellowstone Park Mud Pot
Yellowstone Morning Glory Pool
Anaerobic Chemotrophs
Members of genus Clostridium are Gram-
positive rods
Produce endospores
Common inhabitant of soil
Organisms in this genus ferment wide variety
of compounds to produce energy
Some organisms ferment amino acids in
process of putrefaction
the anaerobic decomposition of organic matter by
bacteria and fungi that results in obnoxiously
odorous products; rotting.
Anaerobic Chemotrophs
Lactic acid bacteria are
Gram-positive organisms
that produce lactic acid as an
end product of fermentation
Includes Streptococcus,
Enterococcus,
Lactococcus,
Lactobacillus,
Leuconostoc
Most organisms of this group
can grow in aerobic
environments but are
obligate fermenters
Anaerobic Chemotrophs
Propionibacterium species are Gram-positive
rods
Organisms produce propionic acid as end
product of fermentation
Essential in the production of Swiss cheese
These organisms can also ferment lactic acid
Principle bacteria of acne and foot odor
Can extract residual energy from waste product
of other organisms
Anoxygenic Phototrophs
Anoxygenic phototrophs oxidize hydrogen
sulfide (H2S) or organic molecules when
making NADPH
Many organisms inhabit restricted ecological
niches
Aquatic habitats such as bogs, lakes and
upper layers of mud
Includes purple bacteria and green bacteria
Anoxygenic Phototrophs
Purple bacteria
Gram-negative organisms
Appear red, orange or purple due
to pigments used in
photosynthesis
Purple sulfur bacteria found
in habitats such as sulfur
springs
Prefer hydrogen sulfide to
generate reducing power
Most organisms strict
anaerobes and
phototrophs
Some can grow aerobically
and in absence of light
Anoxygenic Phototrophs
Purple non-sulfur bacteria
Found in variety of aquatic habitats
Prefer to use organic source of electrons in
production of reducing power
Moist soil, bogs and paddy fields
Distinguishes them from purple sulfur bacteria
Remarkably diverse metabolism
Most can grow aerobically and in absence of light
The Great Salt Lake,
Utah
Anaerobic purple sulfur
bacteria found at the
interface of the very salty
(25%) deeper water with
the less salty (5-12 %)
surface water. (Produce H2S)
Shown against the green
phytoplankton of the
surface water. (Use H2S as an
electron source for energy production)
Anoxygenic Phototrophs
Green bacteria
Gram-negative organisms
Typically green or brown
Green sulfur bacteria
Found in habitats similar
to purple sulfur bacteria
Use hydrogen sulfide as
source of electrons
Many lack flagella but
have gas vesicles
All are strict anaerobes
Anoxygenic Phototrophs
Green non-sulfur bacteria
Characterized by filamentous growth
Metabolically resemble purple non-sulfur
bacteria
Use organic molecules to generate reducing
power
Can grow aerobically and in absence of light
Oxygenic Phototrophs
Photosynthetic bacteria that use water as
source of electrons
Oxidation of water liberates oxygen
Cyanobacteria thought to be earliest organism
of group
Cyanobacteria act as primary producers
Harvest sunlight to produce organic compounds
through conversion of carbon dioxide
Oxygenic Phototrophs
The cyanobacteria
Includes more than 60 genera
Inhabit wide range of
environments
Aquatic to terrestrial
Able to convert nitrogen gas to
ammonia (NH3)
Nitrogen fixation
Some organisms single celled
Form multicellular
associations called trichome
Hair like structures
Oxygenic Phototrophs
Nitrogen-fixing
cyanobacteria
Important ecologically
Can incorporate both
nitrogen gas and
carbon dioxide into
organic material
Supports growth of
other organisms
Helps control
atmospheric carbon
dioxide
heterocyst
Fixation occurs in thick-
walled heterocyst
Protects the break
down of nitrogenase
from oxygen
N2 + 8H+ + 8e− + 16 ATP → 2NH3 + H2 + 16ADP + 16 Pi
Aerobic Chemolithotrophs
Obtain energy oxidizing reduced inorganic
chemicals
Uses oxygen as terminal electron acceptor
Includes sulfur-oxidizing bacteria, nitrifiers and
hydrogen-oxidizing bacteria
Aerobic Chemolithotrophs
Sulfur-oxidizing bacteria are Gram-negative rods or
spirals
Grow in filaments
Obtain energy through oxidation of reduced sulfur
Including hydrogen sulfide, elemental sulfur and
thiosulfate
Molecular oxygen serves as terminal electron acceptor
This produces sulfuric acid
Aerobic Chemolithotrophs
Filamentous sulfur oxidizers
live in sulfur springs, sewage
polluted waters and on
surface of aquatic sediments
Causes bulking in sewage
treatment facilities
Interferes with the separation
of solid sludge and liquid
effluent
Bulking helps water
treatment but harms sewage
disposal
Aerobic Chemolithotrophs
Unicellular sulfur oxidizers found in both
terrestrial and aquatic environments
Responsible for bioleaching through oxidation
of metal sulfides producing sulfuric acid (H2SO4)
and liquid metal
Some species produce enough acid to lower
pH to 1.0
Aerobic Chemolithotrophs
Nitrifiers
Diverse group of Gram-negative bacteria
Oxidize inorganic nitrogen to obtain energy
Nitrogen such as ammonia and nitrite
Important in the breakdown of ammonia containing waste
Nitrogen polluted waters become hypoxic
As nitrogen is oxidized oxygen is consumed
Nitrifiers encompass two metabolically distinctive groups
Ammonia oxidizers
Nitrite oxidizers
Aerobic Chemolithotrophs
Hydrogen-oxidizing bacteria are Gram-
negative bacteria
Obligate chemolithotrophs
Tend to thermophilic
Found primarily in hot springs
Some members thrive at 95°C
Aerobic Chemoorganotrophs
Oxidized organic compounds to obtain
energy
Use oxygen as terminal electron acceptor
Include tremendous variety of organisms
Chemoorganotrophs can be classified as
Obligate aerobes
Facultative anaerobes
Aerobic Chemoorganotrophs
Obligate aerobes obtain energy Mycobacterium
using aerobic respiration
Gram-positive bacterium
exclusively
Live on dead and decaying
matter
None use fermentation
Characteristic genera include
Pseudomonas
Gram-negative rods
Motile and often pigmented
Gram-positive cocci found
Common opportunistic
in soil and dust
pathogen
Produce yellow pigmented Thermus and Deinococcus
colonies
Both have scientific and
commercial uses
Micrococcus
Thermus produces Taq
polymerase
Dinococcus used to clean
up radioactive
contamination
Aerobic Chemoorganotrophs
Facultative anaerobes preferentially use aerobic
respiration
Can use fermentation as alternative in absence of
oxygen
Characteristic genera include
Corynebacterium
Gram-positive pleomorphic rods
Inhabit soil, water and surface of
plants
Enterobacteriaceae
Gram-negative rods
Commonly referred to as enterics
Reside in intestinal tract
Thriving in
Terrestrial Environments
Numerous genera that inhabit soil can
form resting stages that enable survival in
dry periods
Endospores, cysts, fruiting bodies, and
mycelium are examples of resting stage
structures
Bacillus and Clostridium species
produce endospores
Azobactor species produce cysts
Myxobacteria species form fruiting
bodies; social aggregations
Streptomyces species form mycelium
Endospores tend to be more resistant to
environmental insult than cysts or fruiting
bodies
Thriving in
Terrestrial Environments
Bacteria associated with plants
use different means to obtain
nutrients
Agrobacterium produce plant
tumors to gain nutrient
These tumors are often fatal to
plant
Rhizobium have a mutually
beneficial relationship with plants
Organisms fix nitrogen that is
used for a nutrient source for the
plant
Thriving in Aquatic Environments
Organisms produced numerous
mechanisms for nutrient
acquisition and retention
Clustering within a sheath
Bacteria form chains
encased in tube which
enables them to find
favorable habitat
Includes genera Sphaerotilus
and Leptothrix
Derive nutrient from other
organisms
Bdellovibrio prey on other
organisms Form plaques on
lawns of other bacteria
Bioluminescent bacteria
establish relationships with
other animals for food and
protection; Quorum sensing
Legionella live inside
protected confines of
protozoa
Thriving in
Aquatic Environments
Organisms produced numerous
mechanisms for nutrient
acquisition and retention
Move by unusual means
Spirochetes move via axial
filaments in corkscrew
motion
Magnetotactic bacteria
move by means of magnetic
crystals aligning them with
earth’s magnetism
Formation of storage
Spirillum species form
volutin granules to store
phosphate
Certain marine bacteria
store sulfur and nitrate for
oxidation and reduction
Gives advantage to bacteria
in certain environments
Animals as Habitats
Bodies of animals provide wide variety of
ecological habitats for bacteria
Skin inhabited by Staphylococcal species
Mucous membranes is inhabited by
numerous genera including Bacteriods,
Bifidobacterium, Campylobacter and
Helicobacter, Neisseria and Treponema
Bacteria that are obligate intracellular
parasites including Rickettsia, Orientia and
Ehrlicia reside in blood sucking arthropods
Significant component of skin flora
Mainly ticks or lice
Coxiella transmitted person to person
without arthropod vector
Archaea that Thrive in
Extreme Conditions
Extreme halophiles are Extreme thermophiles are
found in high salt
environments
Salt lakes, soda lakes
and brines
Most require 9% salt
concentration
Includes genera
Halobacterium,
Halorubrum,
Natronobacterium and
Natronococcus
found in regions of volcanic
and thermal vents as well as
sulfurous fissures and hot
springs
Methanothermus grows at
temperatures as high as 97°C
Pyrolobus fumarii grows
between 90°C and 113°C
Sulfolobus species grow only
above 50°C
Also require pH between 1
and 6
Archaea that Thrive in
Extreme Conditions
Thermophilic extreme
acidophiles grow at
extremely high temperature
and low pH
Two significant genera
Thermoplasma
Grow optimally at pH
of 2
Some species lyse at
neutral pH
Picrophilus
Optimal growth below
pH 1