Chapter 17 Microbial Ecology 2
? Methane and methanogenesis
? Rumen microbial ecology
? Biogeochemical cycles,nitrogen
? Biogeochemical cycles,sulfur
? Biogeochemical cycles,iron
? Microbial leaching
? Biogeochemical cycles,trace metals and mercury
? Petroleum and natural gas (methane) biodegradation
? Biodegradation of xenobiotics
? Sewage and wastewater microbiology
? Plant-microorganism interactions,Crown and gall and hairy
root
? Root nodule bacteria and symbiosis with legumes
? Methanogenesis and Syntrophy
? Methane production is carried out by a group
of Archaea,the methanogens,which are
obligate anaerobes:
4 H2 + CO2 CH4 + 2H2O
DGo’= -130 kJ/reaction
? Substrates microbially converted to methane:
methanol,formate,methylcaptan (CH3SH),acetate
and methylamines
Anoxic
Decomposition
? Various groups of
fermentative
anaerobes act
together in the
conversion of
complex organic
materials ultimately
to methane and CO2
Primary fermenters and
Secondary fermenters
? Primary fermenters,consume glucose to a
variety of fermentation products (acetate,
propionate,butyrate,succinate,alcohols,
hydrogen and CO2.
? Secondary fermenters,key organisms in the
conversion of complex organic materials to
methane (espacially the H2-producing fatty acid-
oxidizing bacteria).
Syntrophy
? Syntrophy,eating together.
? Syntrophomonas and Syntrophobacter,
H2 producers,collectively referred to
as syntrophs,dependent on syntrophic
relationships with other bacteria (in
this case,H2-consuming bacteria)
Microorganisms from the
hindgut of the termite
Zootermopsis angusticolis
? Sources of atmospheric
methane (biogenic):
? Ruminants
? Paddy fields
? Swamps
? Termites
? Ocean/Lakes
? Others
? Abiogenic
Rumen Microbial Ecosystem
? Herbivorous mammals that possess a special organ,the rumen are
called ruminants,Within rumen,digestion of cellulose and other
plant polysaccharides occurs through activities of microorganisms
食道
蜂巢胃
重瓣胃 皱胃
Biochemical reactions
in the rumen
Biogeochemical Cycles:
Nitrogen
The Global Nitrogen Cycles
Redox cycle
for Sulfur
The global sulfur cycle
Biogeochemical cycles,iron
? Bacterial iron reduction and oxidation
Fe2+ + 1/4O2 + 2OH-1 + 1/2H2O Fe(OH)3
Ferrous iron oxidation at acid pH:
Thiobacillus ferrooxidans,
an iron-oxidizing bacterium,
is strict acidophile,a small
number of cells can be
responsible for precipitating
a large amount of iron.
Pyrite oxidation
? One of the most common forms of iron and
sulfur in nature is pyrite (FeS2),in mining
operation,a slow chemical reaction occurs:
FeS2 + 31/2O2 + H2O Fe2+ + 2SO42- + 2H+
Fe2+ Thiobacillus ferrooxidans Fe3+
FeS2 + 14Fe3+ + 8H2O 15Fe2+ + 2SO42- + 16H+
Spontaneous
Role of iron-oxidizing bacteria in the oxidation of the mineral pyrite
? Methane and methanogenesis
? Rumen microbial ecology
? Biogeochemical cycles,nitrogen
? Biogeochemical cycles,sulfur
? Biogeochemical cycles,iron
? Microbial leaching
? Biogeochemical cycles,trace metals and mercury
? Petroleum and natural gas (methane) biodegradation
? Biodegradation of xenobiotics
? Sewage and wastewater microbiology
? Plant-microorganism interactions,Crown and gall and hairy
root
? Root nodule bacteria and symbiosis with legumes
? Methanogenesis and Syntrophy
? Methane production is carried out by a group
of Archaea,the methanogens,which are
obligate anaerobes:
4 H2 + CO2 CH4 + 2H2O
DGo’= -130 kJ/reaction
? Substrates microbially converted to methane:
methanol,formate,methylcaptan (CH3SH),acetate
and methylamines
Anoxic
Decomposition
? Various groups of
fermentative
anaerobes act
together in the
conversion of
complex organic
materials ultimately
to methane and CO2
Primary fermenters and
Secondary fermenters
? Primary fermenters,consume glucose to a
variety of fermentation products (acetate,
propionate,butyrate,succinate,alcohols,
hydrogen and CO2.
? Secondary fermenters,key organisms in the
conversion of complex organic materials to
methane (espacially the H2-producing fatty acid-
oxidizing bacteria).
Syntrophy
? Syntrophy,eating together.
? Syntrophomonas and Syntrophobacter,
H2 producers,collectively referred to
as syntrophs,dependent on syntrophic
relationships with other bacteria (in
this case,H2-consuming bacteria)
Microorganisms from the
hindgut of the termite
Zootermopsis angusticolis
? Sources of atmospheric
methane (biogenic):
? Ruminants
? Paddy fields
? Swamps
? Termites
? Ocean/Lakes
? Others
? Abiogenic
Rumen Microbial Ecosystem
? Herbivorous mammals that possess a special organ,the rumen are
called ruminants,Within rumen,digestion of cellulose and other
plant polysaccharides occurs through activities of microorganisms
食道
蜂巢胃
重瓣胃 皱胃
Biochemical reactions
in the rumen
Biogeochemical Cycles:
Nitrogen
The Global Nitrogen Cycles
Redox cycle
for Sulfur
The global sulfur cycle
Biogeochemical cycles,iron
? Bacterial iron reduction and oxidation
Fe2+ + 1/4O2 + 2OH-1 + 1/2H2O Fe(OH)3
Ferrous iron oxidation at acid pH:
Thiobacillus ferrooxidans,
an iron-oxidizing bacterium,
is strict acidophile,a small
number of cells can be
responsible for precipitating
a large amount of iron.
Pyrite oxidation
? One of the most common forms of iron and
sulfur in nature is pyrite (FeS2),in mining
operation,a slow chemical reaction occurs:
FeS2 + 31/2O2 + H2O Fe2+ + 2SO42- + 2H+
Fe2+ Thiobacillus ferrooxidans Fe3+
FeS2 + 14Fe3+ + 8H2O 15Fe2+ + 2SO42- + 16H+
Spontaneous
Role of iron-oxidizing bacteria in the oxidation of the mineral pyrite
