Beggiatoa Fig. 6.14a, Thiospira) grouped in the family
Thiotricaceae; two other families (Piscirickettsiaceae and
Francisellaceae) are also part of this order.
The methylotrophic bacteria order (Methylococcales) is
represented by family Methylococcaceae (Methylococcus,
Methylobacter), and the Cardiobacteriales order with family
Cardiobacteriaceae (Cardiobacterium) are also present in
this Gammaproteobacteria class.
The Class Deltaproteobacteria
With seven orders, it includes among others the majority of
sulfate-reducing bacteria which are chemoorganotrophic
anaerobic bacteria for most, some may be chemolithotrophic, using sulfate as electron acceptor
(Desulfovibrio, Fig. 6.14h, m, o; Desulfobacter, Fig. 6.14r;
Desulfobulbus, Fig. 6.14l; Desulfobacterium, Fig. 6.14i, p)
and anaerobic bacteria using ferric iron as electron acceptor
(Geobacter, Pelobacter). These bacteria are grouped into
four orders of this class.
The order Desulfurellales with family Desulfurellaceae
contains the genus Desulfurella.
The order Desulfovibrionales includes three families,
Desulfovibrionaceae (Desulfovibrio), especially encountered in coastal environments and capable of degrading
partially simple organic compounds, Desulfomicrobiaceae
(Desulfomicrobium), and Desulfohalobiaceae (Desulfohalobium, Desulfonatronovibrio, etc.), these latter including
the halophilic sulfate-reducing bacteria isolated from hypersaline environments.
The Desulfobacterales with families Desulfobacteraceae
(Desulfobacter, Fig. 6.14r; Desulfobacterium, Fig. 6.14i, p),
Desulfobulbaceae (Desulfobulbus, Fig. 6.14l), and
Desulfoarculaceae (Desulfoarculus, Desulfomonile) correspond to sulfate-reducing bacteria isolated from diverse
environments, such as oceans, soils, deep earth, oil deposits,
etc. They are able to degrade some complex organic
compounds and of biotransformation of metals.
The order Desulfomonadales contains sulfate-reducing
bacteria in the family Desulfomonadaceae (Desulfomonas)
and anaerobic chemoorganotrophic iron-reducing bacteria in
families Geobacteraceae (Geobacter) and Pelobacteraceae
(Pelobacter).
In this class, there is also the order Syntrophobacterales with
two families, Syntrophobacteraceae (Syntrophobacter) and
Syntrophaceae (Syntrophus), which includes anaerobic bacteria
living in syntrophy requiring interspecies hydrogen transfer but
also some sulfate-reducing bacteria (Desulfacinum).
The order Bdellovibrionales (Bdellovibrionaceae)
contains bacteriological predatory bacteria (Bdellovibrio or
Vampirovibrio).
Finally, the order Myxococcales with the two families
Myxococcaceae (Myxococcus, etc.) and Polyangiaceae
(Polyangium, Chondromyces, etc.) is composed of bacteria
with fruiting structures (myxobacteria).
The Class Epsilonproteobacteria
The fifth class of this great phylum contains some specific
bacteria such as Campylobacter, sulfur-oxidizing bacteria
(Thiovulum) grouped in the family Campylobacteraceae,
and the pyloric gastric pathogen (Helicobacter pylori) in
the family Helicobacteraceae.
The Class Zetaproteobacteria
This sixth and last class of Proteobacteria includes an order,
the Mariprofundales, containing a single family, the
Mariprofundaceae with a single genus Mariprofundus
corresponding to microaerophilic chemolithotrophic curved
rods, using iron as electron donor, with filamentous
structures containing iron oxyhydroxide. One species
Mariprofundus ferrooxydans was isolated from iron-rich
microbial mats near deep hydrothermal vents of the Pacific
Ocean.
The Phylum Bacteroidetes
It is also an important phylum of Gram-negative bacteria
that includes aerobic and anaerobic heterotrophic bacteria
living in soil or in water bodies and aquatic sediments. It is
often called CFB group (Cytophaga-FlavobacteriumBacteroides). It is divided into three classes.
Bacteroidia class with order Bacteroidales which
contains four families corresponding to anaerobic bacteria
encountered in environments rich in organic matter often
from urban waste or fermenting materials, feces, or
composted material. Families Bacteroidaceae (Bacteroides,
etc.), Rickenellaceae (Rickenella, etc.), Porphyromonadaceae
(Porphyromonas), and Prevotellaceae (Prevotella) constitute
this order.
Flavobacteria class with Flavobacteriales order includes
the families of Flavobacteriaceae (Flavobacterium,
Cellulophaga, Polaribacter) of Myroidaceae (Myroides)
and Blattabacteriaceae (Blattabacterium) including
chemoorganotrophic aerobic or denitrifying bacteria which
play an important role in the degradation of organic matter in
soils and biodegradation of xenobiotics.
Sphingobacteria class in which the order Sphingobacteriales includes five families of chemoorganotrophic aerobic or denitrifying flexuous filamentous moving or
gliding bacteria involved in the degradation of organic
pollutants and xenobiotics: the Sphingobacteriaceae
(Sphingobacterium), the Saprospiraceae (Saprospira),
the Flexibacteaceae (Flexibacter, Cytophaga), the
Flammeovirgaceae (Flammeovirga, Flexithrix, etc.), and
Crenotrichaceae (Crenothrix, Toxothrix). From an
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183
Thiotricaceae; two other families (Piscirickettsiaceae and
Francisellaceae) are also part of this order.
The methylotrophic bacteria order (Methylococcales) is
represented by family Methylococcaceae (Methylococcus,
Methylobacter), and the Cardiobacteriales order with family
Cardiobacteriaceae (Cardiobacterium) are also present in
this Gammaproteobacteria class.
The Class Deltaproteobacteria
With seven orders, it includes among others the majority of
sulfate-reducing bacteria which are chemoorganotrophic
anaerobic bacteria for most, some may be chemolithotrophic, using sulfate as electron acceptor
(Desulfovibrio, Fig. 6.14h, m, o; Desulfobacter, Fig. 6.14r;
Desulfobulbus, Fig. 6.14l; Desulfobacterium, Fig. 6.14i, p)
and anaerobic bacteria using ferric iron as electron acceptor
(Geobacter, Pelobacter). These bacteria are grouped into
four orders of this class.
The order Desulfurellales with family Desulfurellaceae
contains the genus Desulfurella.
The order Desulfovibrionales includes three families,
Desulfovibrionaceae (Desulfovibrio), especially encountered in coastal environments and capable of degrading
partially simple organic compounds, Desulfomicrobiaceae
(Desulfomicrobium), and Desulfohalobiaceae (Desulfohalobium, Desulfonatronovibrio, etc.), these latter including
the halophilic sulfate-reducing bacteria isolated from hypersaline environments.
The Desulfobacterales with families Desulfobacteraceae
(Desulfobacter, Fig. 6.14r; Desulfobacterium, Fig. 6.14i, p),
Desulfobulbaceae (Desulfobulbus, Fig. 6.14l), and
Desulfoarculaceae (Desulfoarculus, Desulfomonile) correspond to sulfate-reducing bacteria isolated from diverse
environments, such as oceans, soils, deep earth, oil deposits,
etc. They are able to degrade some complex organic
compounds and of biotransformation of metals.
The order Desulfomonadales contains sulfate-reducing
bacteria in the family Desulfomonadaceae (Desulfomonas)
and anaerobic chemoorganotrophic iron-reducing bacteria in
families Geobacteraceae (Geobacter) and Pelobacteraceae
(Pelobacter).
In this class, there is also the order Syntrophobacterales with
two families, Syntrophobacteraceae (Syntrophobacter) and
Syntrophaceae (Syntrophus), which includes anaerobic bacteria
living in syntrophy requiring interspecies hydrogen transfer but
also some sulfate-reducing bacteria (Desulfacinum).
The order Bdellovibrionales (Bdellovibrionaceae)
contains bacteriological predatory bacteria (Bdellovibrio or
Vampirovibrio).
Finally, the order Myxococcales with the two families
Myxococcaceae (Myxococcus, etc.) and Polyangiaceae
(Polyangium, Chondromyces, etc.) is composed of bacteria
with fruiting structures (myxobacteria).
The Class Epsilonproteobacteria
The fifth class of this great phylum contains some specific
bacteria such as Campylobacter, sulfur-oxidizing bacteria
(Thiovulum) grouped in the family Campylobacteraceae,
and the pyloric gastric pathogen (Helicobacter pylori) in
the family Helicobacteraceae.
The Class Zetaproteobacteria
This sixth and last class of Proteobacteria includes an order,
the Mariprofundales, containing a single family, the
Mariprofundaceae with a single genus Mariprofundus
corresponding to microaerophilic chemolithotrophic curved
rods, using iron as electron donor, with filamentous
structures containing iron oxyhydroxide. One species
Mariprofundus ferrooxydans was isolated from iron-rich
microbial mats near deep hydrothermal vents of the Pacific
Ocean.
The Phylum Bacteroidetes
It is also an important phylum of Gram-negative bacteria
that includes aerobic and anaerobic heterotrophic bacteria
living in soil or in water bodies and aquatic sediments. It is
often called CFB group (Cytophaga-FlavobacteriumBacteroides). It is divided into three classes.
Bacteroidia class with order Bacteroidales which
contains four families corresponding to anaerobic bacteria
encountered in environments rich in organic matter often
from urban waste or fermenting materials, feces, or
composted material. Families Bacteroidaceae (Bacteroides,
etc.), Rickenellaceae (Rickenella, etc.), Porphyromonadaceae
(Porphyromonas), and Prevotellaceae (Prevotella) constitute
this order.
Flavobacteria class with Flavobacteriales order includes
the families of Flavobacteriaceae (Flavobacterium,
Cellulophaga, Polaribacter) of Myroidaceae (Myroides)
and Blattabacteriaceae (Blattabacterium) including
chemoorganotrophic aerobic or denitrifying bacteria which
play an important role in the degradation of organic matter in
soils and biodegradation of xenobiotics.
Sphingobacteria class in which the order Sphingobacteriales includes five families of chemoorganotrophic aerobic or denitrifying flexuous filamentous moving or
gliding bacteria involved in the degradation of organic
pollutants and xenobiotics: the Sphingobacteriaceae
(Sphingobacterium), the Saprospiraceae (Saprospira),
the Flexibacteaceae (Flexibacter, Cytophaga), the
Flammeovirgaceae (Flammeovirga, Flexithrix, etc.), and
Crenotrichaceae (Crenothrix, Toxothrix). From an
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183