surface soil, sediment, or decaying leaves in the litter of
forests. The suborder Micrococcinae includes several
families with a Gram-positive cocci or irregularly shaped
cells or sticks depending on the age of the culture: the family
Micrococcaceae (Micrococcus, Leucobacter, Arthrobacter,
etc.) consists of aerobic bacteria isolated from soil and
freshwater or coastal or in the oral cavity (Stomatococcus),
the Brevibacteriaceae (Brevibacterium) involve irregularly
shaped bacteria, isolated from soils rich in organic matter,
and the Cellulomonadaceae (Cellulomonas) include aerobic
and fermentative bacteria capable of degrading cellulose in
soils;
families
Dermabacteraceae
(Dermabacter),
Dermatophilaceae (Dermatophilus), Intrasporangiaceae
(Intrasporangium), Jonesiaceae (Jonesia), Microbacteriaceae
(Microbacterium,
Agromyces,
etc.),
Beutenbergiaceae (Beutenbergia), and Promicromonosporaceae (Promicromonospora) correspond to different
soil isolated bacteria, irregularly shaped or filamentous,
important in the degradation of organic matter including
macromolecules and polymers. The suborder Corynebacterineae includes several soil bacteria, many of which are
pathogens: Corynebacteriaceae family (Corynebacterium)
with Corynebacterium diphtheriae (diphtheria agent) and
Corynebacterium glutamicum, a microorganism used in biotechnology for the synthesis of many molecules; it also
contains other corynebacteria, organisms commonly found
in soil and water, capable of degrading macromolecules of
some xenobiotics; the family Mycobacteriaceae with the
genus Mycobacterium consists of microorganisms of soil
and water, some of which are pathogens such as Mycobacterium tuberculosis, the agent of tuberculosis, the bacterial
disease that causes the greatest number of deaths worldwide,
and Mycobacterium leprae, the agent of leprosy; these bacteria are characterized by their resistance to environmental
factors that gives them their envelopes made of waxy
mycolic acids. Family Nocardiaceae with Nocardia and
Rhodococcus consists of chemoorganotrophic bacteria of
soil and aquatic sediments, active in the biodegradation of
organic pollutants in soils. Some Nocardia (N. asteroides, N.
cyriacigeorgica) are pathogens of animals, and finally,
families Dietziaceae, Gordoniaceae, Tsukamurellaceae,
and Williamsiaceae contain heterotrophic and saprophytic
irregularly shaped soil bacteria forming branches and buds.
The suborder Micromonosporineae with a single family
(Micromonosporaceae) includes nine types of bacteria in
soil and aquatic environments, chemoorganotrophic, some
of
which
are
capable
of
producing
spores
(Micromonospora). They are irregularly shaped bacteria
with buds that develop into filamentous mycelium
(Actinoplanes) and produce spores inside a sporangium
(Dactylosporangium). The suborder Propionibacterineae
includes two families: Propionibacteriaceae (Propionibacterium,
Luteococcus,
Propioniferax)
gathering
aerotolerant or anaerobic bacteria, producing lactic acid
fermentation, producing propionic acid (flavor of some
cheeses), used in the dairy industry. Some species may be
pathogenic, while others are inhabitants of the digestive tract
and contribute to the intestinal flora. Nocardioidaceae
(Nocardioides) bacteria are chemoorganotrophic, filamentous soil saprophytes, and some are able to degrade
hydrocarbons. The suborder Pseudonocardineae with
two families Pseudonocardiaceae (Pseudonocardia) and
Actinosynnemataceae (Actinosynnema) group heterotrophic
saprophytic filamentous soil bacteria. The suborder
Streptomycineae with the family Streptomycetaceae including the genus Streptomyces contains chemoorganotrophic
filamentous soil saprophytic bacteria. These bacteria form
branched filaments, producing hyphae, and develop aerial
mycelia with sporophores (bodies containing spores that are
later released), which led to a confusion with the microscopic Fungi for a long time. These bacteria produce
antibiotics and are the source of the majority of known
antibiotics. There are also pathogenic species of plants,
especially potato (S. scabies). The suborder Streptosporangineae with three families (Streptosporangiaceae,
Nocardiopsaceae, Thermomonosporaceae) groups filamentous bacteria producing sporangia and containing spores
which are close to the Streptomycetaceae. The suborder
Frankineae is divided into six families. The family
Frankiaceae with the genus Frankia (Fig. 6.15d, e) is a filamentous bacteria of the soil, often in symbiotic association
with plants such as Frankia alni (symbiont of alder roots;
Normand and Lalonde 1982). Families Acidothermaceae,
Cryptosporangiaceae, Geodermatophilaceae, Nakamurellaceae, and Sporichaetaceae also contain heterotrophic
saprophytic soil bacteria, forming mycelia. Some of these
bacteria have special habitats such as Acidothermus found in
hot springs in Yellowstone (the USA) or Geodermatophilus
and Modestobacter found in irradiated soils. The suborder
Glycomycineae with the genus Glycomyces also corresponds
to mycelial saprophytic soil bacteria.
The order Bifidobacteriales with a family (Bifidobacteriaceae) includes Bifidobacterium bifidus, a bacterium of
the digestive tract used as an additive in some yogurts.
6.7
Conclusion
Microorganisms have been on earth for billions of years (cf.
Chap. 4) and have colonized almost all ecological niches,
even those created by humans in recent decades. They have a
very important adaptive potential. If a science fiction apocalyptic scenario such as that initiated by a meteorite impact or
a massive volcanic episode of the kind that produced the
Deccan Traps were to occur and eliminate a large proportion
of taxa living on earth today, it is likely that life would not
188
P. Caumette et al.
forests. The suborder Micrococcinae includes several
families with a Gram-positive cocci or irregularly shaped
cells or sticks depending on the age of the culture: the family
Micrococcaceae (Micrococcus, Leucobacter, Arthrobacter,
etc.) consists of aerobic bacteria isolated from soil and
freshwater or coastal or in the oral cavity (Stomatococcus),
the Brevibacteriaceae (Brevibacterium) involve irregularly
shaped bacteria, isolated from soils rich in organic matter,
and the Cellulomonadaceae (Cellulomonas) include aerobic
and fermentative bacteria capable of degrading cellulose in
soils;
families
Dermabacteraceae
(Dermabacter),
Dermatophilaceae (Dermatophilus), Intrasporangiaceae
(Intrasporangium), Jonesiaceae (Jonesia), Microbacteriaceae
(Microbacterium,
Agromyces,
etc.),
Beutenbergiaceae (Beutenbergia), and Promicromonosporaceae (Promicromonospora) correspond to different
soil isolated bacteria, irregularly shaped or filamentous,
important in the degradation of organic matter including
macromolecules and polymers. The suborder Corynebacterineae includes several soil bacteria, many of which are
pathogens: Corynebacteriaceae family (Corynebacterium)
with Corynebacterium diphtheriae (diphtheria agent) and
Corynebacterium glutamicum, a microorganism used in biotechnology for the synthesis of many molecules; it also
contains other corynebacteria, organisms commonly found
in soil and water, capable of degrading macromolecules of
some xenobiotics; the family Mycobacteriaceae with the
genus Mycobacterium consists of microorganisms of soil
and water, some of which are pathogens such as Mycobacterium tuberculosis, the agent of tuberculosis, the bacterial
disease that causes the greatest number of deaths worldwide,
and Mycobacterium leprae, the agent of leprosy; these bacteria are characterized by their resistance to environmental
factors that gives them their envelopes made of waxy
mycolic acids. Family Nocardiaceae with Nocardia and
Rhodococcus consists of chemoorganotrophic bacteria of
soil and aquatic sediments, active in the biodegradation of
organic pollutants in soils. Some Nocardia (N. asteroides, N.
cyriacigeorgica) are pathogens of animals, and finally,
families Dietziaceae, Gordoniaceae, Tsukamurellaceae,
and Williamsiaceae contain heterotrophic and saprophytic
irregularly shaped soil bacteria forming branches and buds.
The suborder Micromonosporineae with a single family
(Micromonosporaceae) includes nine types of bacteria in
soil and aquatic environments, chemoorganotrophic, some
of
which
are
capable
of
producing
spores
(Micromonospora). They are irregularly shaped bacteria
with buds that develop into filamentous mycelium
(Actinoplanes) and produce spores inside a sporangium
(Dactylosporangium). The suborder Propionibacterineae
includes two families: Propionibacteriaceae (Propionibacterium,
Luteococcus,
Propioniferax)
gathering
aerotolerant or anaerobic bacteria, producing lactic acid
fermentation, producing propionic acid (flavor of some
cheeses), used in the dairy industry. Some species may be
pathogenic, while others are inhabitants of the digestive tract
and contribute to the intestinal flora. Nocardioidaceae
(Nocardioides) bacteria are chemoorganotrophic, filamentous soil saprophytes, and some are able to degrade
hydrocarbons. The suborder Pseudonocardineae with
two families Pseudonocardiaceae (Pseudonocardia) and
Actinosynnemataceae (Actinosynnema) group heterotrophic
saprophytic filamentous soil bacteria. The suborder
Streptomycineae with the family Streptomycetaceae including the genus Streptomyces contains chemoorganotrophic
filamentous soil saprophytic bacteria. These bacteria form
branched filaments, producing hyphae, and develop aerial
mycelia with sporophores (bodies containing spores that are
later released), which led to a confusion with the microscopic Fungi for a long time. These bacteria produce
antibiotics and are the source of the majority of known
antibiotics. There are also pathogenic species of plants,
especially potato (S. scabies). The suborder Streptosporangineae with three families (Streptosporangiaceae,
Nocardiopsaceae, Thermomonosporaceae) groups filamentous bacteria producing sporangia and containing spores
which are close to the Streptomycetaceae. The suborder
Frankineae is divided into six families. The family
Frankiaceae with the genus Frankia (Fig. 6.15d, e) is a filamentous bacteria of the soil, often in symbiotic association
with plants such as Frankia alni (symbiont of alder roots;
Normand and Lalonde 1982). Families Acidothermaceae,
Cryptosporangiaceae, Geodermatophilaceae, Nakamurellaceae, and Sporichaetaceae also contain heterotrophic
saprophytic soil bacteria, forming mycelia. Some of these
bacteria have special habitats such as Acidothermus found in
hot springs in Yellowstone (the USA) or Geodermatophilus
and Modestobacter found in irradiated soils. The suborder
Glycomycineae with the genus Glycomyces also corresponds
to mycelial saprophytic soil bacteria.
The order Bifidobacteriales with a family (Bifidobacteriaceae) includes Bifidobacterium bifidus, a bacterium of
the digestive tract used as an additive in some yogurts.
6.7
Conclusion
Microorganisms have been on earth for billions of years (cf.
Chap. 4) and have colonized almost all ecological niches,
even those created by humans in recent decades. They have a
very important adaptive potential. If a science fiction apocalyptic scenario such as that initiated by a meteorite impact or
a massive volcanic episode of the kind that produced the
Deccan Traps were to occur and eliminate a large proportion
of taxa living on earth today, it is likely that life would not
188
P. Caumette et al.