Transcript Logistics - Phoenix College

Prokaryotes
Bacteria and Archaea
Chapter 27
Small Size
Two Domains
Proteobacteria
Universal ancestor
Domain
Archaea
Eukaryotes
Nanoarchaeotes
Crenarcaeotes
Domain Bacteria
Euryarchaeotes
Korarchaeotes
Gram-positive
bacteria
Cyanobacteria
Spirochetes
Chlamydias
Epsilon
Delta
Gamma
Beta
Alpha
Phylogeny of Domains
Domain
Eukarya
Bacteria include every mode of
nutrition and metabolism
Archaea
• Single celled
microorganisms
• Reproduce asexually
• Identified as separate
Domain in 1977
• First archaea were
discovered in extreme
conditions. Called
extremophiles
6
Halophiles: salt lovers
Thermophiles
Live at very high
temperatures
Methanogens
• Use CO2 to Oxidize
H2 release CH4
• Release methane
• O2 is toxic to them
• Found in anoxic
conditions such as
swamps, deep caves,
and intestines of
animals
Bacteria
1 µm
Spherical
(cocci)
2 µm
Rod-shaped
(bacilli)
5 µm
Spiral
Peptidoglycan Cell Walls
Lipopolysaccharide
Outer
membrane
Cell
wall
Pepridoglycan
layer
Cell
wall
Pepridoglycan
layer
Plasma membrane
Plasma membrane
Protein
Protein
Grampositive
bacteria
Gramnegative
bacteria
20 µm
Gram-positive
Gram-negative
Movement
Internal Membranes
Endospores
• Dormant tough but not
reproductive structures
• Ensures survival of
bacterium. Resistant to
ultraviolet, gamma
radiation, temperature
fluctuation, household
disinfectants...
• found in soil, and water
Bacterial DNA
Bacteria have circular DNA
Bacteria Plasmids
• Extra-chromosome DNA
that is separate from the
bacterial chromosomal
DNA
• Separate self replication
• can be transfered to
other bacteria and other
bacteria species
16
Symbiotic relationships
Bioluminescent bacteria
18
Human symbiotic relationships
Termites have
specialized bacteria
that helps them digest
cellulose
Termites comprise
~50% of the animal
biomass in Africa
Humans have a long history of
using prokaryotes
Commercial use of prokaryotes
Wastewater Treatment
Commercial use of prokaryotes
Bioremediation
Ecosystem Services
Protists
Chapter 28
25
Aquatic Producers are often
Protists
Green Algae
Diatoms
Diatoms
26
What are ‘Protists’
• They are not plants,
animals or fungi
• Diverse assortment
of eukaryotes
• Most are unicellular
with complex cells
• Found in damp soil,
oceans and even
human bodies
27
Nutritional Diversity
The freshwater ciliate Stentor,
a unicellular protozoan (LM)
• Autotrophs
• Heterotrophs
• Mixitrophs
100 µm
100 µm
4 cm
Ceratium tripos, a unicellular marine
dinoflagellate (LM)
Delesseria Sanguinea, a multicellular marine red alga
500 µm
Spirogyra, a filamentous freshwater green alga (insert LM)
28
Asexual Reproduction
29
Sexual Reproduction
30
Ciliates
Cillated Pellicle
31
Paramecium
32
Diatoms
10,000 species
Photosynthetic with golden accessory pigments
33
Diatom
Silica in Cell Wall
34
Psuedopod-equipped Protists
• Heterotrophic
• Psuedopods or
axopods
• With or without
cell walls
• Ameoba is a well
known psuedopod
35
Slime Molds
• Mycetozoans were
thought to be fungi
• Now understood to
be case of
evolutionary
convergence
• Two main branches
– Plasmodial slime
molds
– Cellular slime molds
36
Plasmodial slime mold
one super cell
37
Multicellular Brown Algae:
Phaeophyta
• May grow up to 60 meters
• Provide 3 demensional
habitats for marine
species
• Plant like structures,
holdfast, stipe, and blades
• Pneumatocysts are gasfilled bladders, located at
the base of blades
provides Boyance
38
Laminaria at low tide
39
Kelp Forest
40
Chlorophyta
• Green algae
• Autotrophic
• Plant-like
chloroplasts and
pigments
• Cellulose cell walls
• Red and Green
algae are the closest
relatives to plants
41
Cladophora form large filamentous
mats
42
http://www.youtube.com/watch?v=PoiAKcIls6s&feature=related
43
Fungi and nutrient cycling
Chapters 31 and 54
44
Fungi
Heterotrophic Decomposers or
Symbionts
Fungal Characteristics
• Heterotrophic
– Decomposers
Nematod
e
Hypha
e
25
µm
– Opportunistic parasites
– Many produce
mycotoxins as metabolic
by-products
• Aerobic or facultative
anaerobes
• Cell wall composed of chitin
– more closely related to
animals than plants
• Grow best in warm, moist
environments
Hyphae adapted for trapping and killing
prey
Plant
cell
wall
Fungal
hypha
Haustori
Haustoriu
m
Plant cell
plasma
membran
e
Plant
cell
46
Dimorphic
• Found in two
physical forms:
– Unicellular Yeasts
– Multicellular Molds
and Mushrooms
• Hyphae
• Mycelium =
hyphal mass
Reproduction by Spore Formation
• Asexual
– Haploid spores
formed on hyphae
– Fragmentation
• Broken fragments of
hyphae
• Sexual
– Two mating hyphae
types fuse and produce
spores
Key
Heterokaryotic
stage
Haploid (n)
Heterokaryotic
(unfused nuclei from
different parents)
PLASMOGAMY
(fusion of cytoplasm)
Diploid (2n)
KARYOGAMY
(fusion of nuclei)
Spore-producing
structures
Zygote
Spores
ASEXUAL
REPRODUCTION
Mycelium
SEXUAL
REPRODUCTION
MEIOSIS
GERMINATION
GERMINATION
Spore-producing
structures
Spores
49
Penicillium (Blue-green Mold)
Basidiocarps
Fig. 31-20
52
http://www.youtube.com/watch?v=JeF952Xfz4&feature=relmfu
53
Lichens
(Fungal-Algal Symbiosis)
Lichen Structure
Mycorrhizae
• Plant roots and
symbiotic fungi
• Increased nutrient (P)
absorption
–
–
–
–
Greater surface area
Enzyme excretions
Increased plant bimass
may have originally
started as parasitism
– Most plants have
Mycorrhizae infections
Mycorrhizae
“The Nation that Destroys Its Soil
Destroys Itself” – F.D.R.
Farmland productivity often suffers from
chemical contamination, mineral
deficiencies, acidity, salinity, and poor
drainage
Healthy soils improve plant growth by
enhancing plant nutrition
58
Soil is a living, finite resource
• Plants obtain most of their water
and minerals from the upper
layers of soil
• Living organisms play an
important role in these soil layers
• This complex soil ecosystem is
fragile
• Topsoil contains bacteria, fungi,
algae, other protists, insects,
earthworms, nematodes, and
plant roots
• These organisms help to
decompose organic material and
mix the soil
59
Rocks Contribute Minerals
•
•
•
•
Weathering
Erosion
Transportation
Sedimentation
Grain Size
• Sand
– 2.1 mm to .05 mm
• Silt
– Less than .05 mm but
greater than .002 mm
• Clay
– Less than .002 mm
Soil Texture
• Soil particles are classified
by size; from largest to
smallest they are called
sand, silt, and clay
• Soil is stratified into layers
called soil horizons
• Topsoil consists of mineral
particles, living organisms,
and humus, the decaying
organic material
62
Soil
•
•
•
•
Minerals
Water
Air
Dead Organic
material
• Organisms
Water and soil interact
• Soil particle size
influences:
– water transport
nutrients
– soil moisture
• Water flows through and
evaporates quickly from
sandy soils
• Clay soils bind water
which prevent plants
from absorbing
Litter and Topsoil
• Most plant root
biomass
• Most nutrient
turnover
• Most decomposer
biomass
• Most microbial
activity
Litter Decomposers
2. Global C sources and sinks (CO2)
Net deforestation = 0.9
Atmosphere = 750
+3.2/yr
Combustion = 6
GPP = 120
Plant R = 45
Soil R = 75
560
Rivers = .8
92
90
Soils = 1500
Values are 1015 g C, fluxes are annual
Schlesinger 1997
Oceans = 38000
3. Nutrient cycling
Photosynthetic machinery
is nutrient rich (N, P, Ca, etc.)
Litterfall
Nutrients are lost with
leaf senescence
Decomposition
Nutrient uptake
Decomposition processes
often mediate nutrient
availability for plants
Decomposition over Time
Litter and Topsoil Organisms
Size of Soil Microorganisms
Soil Protozoa
• Decomposers
• Consumers
Producers
Soil Fungi
• Decomposers
• Symbionts
Soil Actinomycetes
• Fungus-like
bacteria
• Some are
symbiotic
with plants
• Some
produce
antibiotics
Soil Bacteria
• Producers
• Decomposers
• Mineralizers
Soil Bacteria and Plant
Nutrition
• The layer of soil bound to the plant’s
roots is the rhizosphere
• The rhizosphere has high microbial
activity because of sugars, amino acids,
and organic acids secreted by roots
78
Rhizobacteria
• Free-living rhizobacteria thrive in the
rhizosphere, and some can enter roots
• Rhizobacteria can play several roles
– Produce hormones that stimulate plant
growth
– Produce antibiotics that protect roots from
disease
– Absorb toxic metals or make nutrients more
available to roots
79
Bacteria in the Nitrogen
Cycle
• Nitrogen is often an important limiting
nutrient for plant growth
• The nitrogen cycle transforms nitrogen
and nitrogen-containing compounds
• Most soil nitrogen comes from actions of
soil bacteria
80
Nitrogen-Fixing Bacteria: A Closer
Look
• N2 is abundant in the atmosphere, but
unavailable to plants
• Nitrogen fixation is the conversion of
nitrogen from N2 to NH3
• Symbiotic relationships with nitrogenfixing bacteria provide some plant
species with a built-in source of available
N
• Most commonly legumes: beans, peas…
81
N2
Atmosphere
N2
Atmosphere
Soil
N2
Nitrogen-fixing bacteria
Denitrifying
bacteria
H+
Nitrate and
nitrogenous
organic
compounds
exported in
xylem to
shoot system
(from soil)
NH4+
Soil
NH3
Ammonifying (ammonia)
bacteria
NH4+
(ammonium)
Nitrifying
bacteria
NO3–
(nitrate)
Organic material (humus)
Root
82
Nitrogen Cycle
Nitrogen Fixation
• N2
NH4+
• Nitrogen gas is
fixed as
ammonium ion.
•Photosynthetic
•Nitrogen Fixing
−Nostoc and Anabaena
•Specialized cells:
heterocysts
Cyanobacteria heterocysts
Non-Photosynthetic Nitrogen
Fixers
• Free-living heterotrophic
bacteria
– Azotobacter
– Azomonas
• Symbiotic heterotrophic
bacteria
– Rhizobium
– Mesquite Trees are
Facultative N-Fixers
Ammonification
C2H2O2 + NH4+
Amino acid
•Carried out by many heterotrophic microbes.
Nitrification
• NH4+ -> NO2- -> NO3-2
• Oxidation carried out by aerobic,
chemoautotrophic (mineralizing) bacteria
Denitrification
• NO3-2
NO2N2
• Pseudomonas and
Paracoccus
• Carried out by
anaerobic, heterotrophic
microbes
• How can we measure
denitrification?
Nitrogen cycle summary
• Nitrogen fixation:
• (Gas) N2  NH4
• Ammonification:
• (organism) Amino Acid  NH4
• Nitrification:
• NH4  NO2  NO3 (Mineral)
• Denitrification:
• (Mineral) NO3  NO2  N2 (Gas)
• Carried out by cyanobacteria, Rhizobium,
89
heterotrophs, bacteria, fungi…