Environmental Microbiology of Aquatic and Waste Systems

78 4 Taxonomy, Physiology, and Ecology of Aquatic Microorganisms

of, and even preference for, extremes of acidity and
temperature. While many prefer neutral to slightly
acidic pH ranges, members of the Crenarchaeal order
Sulfolobales flourish at pH 1–2 and die above pH 7.
Optimum growth temperatures range from 75°C to
105°C and the maximum temperature of growth can be
as high as 113°C (Pyrobolus). Most species are unable
to grow below 70°C, although they can survive for long
periods at lower temperatures. Crenarchaeota contains
representations of organisms which live in a wide
variety of environments including terrestrial environ­
ments (hot springs, geothermal power plants) or in
marine (submarine hot vents, deep oil wells, marine
smokers up to 400°C). Some exist in environments of
over 100°C, while others live at ice cold conditions.
For substrates, they utilize a wide range of gases: CO 2 ,
CO, CH 4 , S 2 O 3 , N 2 , NH 4 (Fig. 4.1 9 ).
(a) Hyperthermophiles in underwater volcanic envi­
ronments
Temperatures as high as 100°C occur around ter­
restrial volcanoes and Sulfolobus and Thermoproteus,
both hyperthermophiles, have been isolated from
such environments.
(b) Hyperthermophiles in land volcanic environments
Archae with the highest optimum temperature of
growth known occur in underwater vents and
near underwater volcanoes. Pyrodictium sp. and
Pyrolobus sp. have optimum temperatures of
growth of 100°C and 106°C respectively and are

found in such environments. Desulforococcus

(90°C, optimum) and Staphylothermus (95°C,

optimum) are also found in that environment.

4.1.6 Microbial Taxonomic Groups Among Eucharia

The Domain Eukarya includes plants, animals, algae,

fungi, and protozoa. The last three are regarded as

microorganisms, although some of them are quite

large. In Fig. 4.2 0 , green algae, brown algae, red algae,

and diatoms are Algae. Diplomonads, Trichomonads,

Ciliates, Flagellates and Slime molds are Protozoa.

4.1.6.1 Protozoa

Protozoa are thought to be the evolutionary ancestors

of all multi­cellular organisms, including plants, fungi,

and animals. The basis for this assumption is that

Protozoa contain members which like plants are pho­

totrophic, as well as members which like animals and

fungi are heterotrophic. Furthermore Protozoa contain

species with intermediate (mixotrophic) trophic

capabilities, i.e., they have the capability for both auto­

and heterotrophic existence. Thus, many dinoflagel­

lates are auxotrophic because they take up vitamins

produced by other organisms; on the other hand, other

Protozoa such as some euglenoids alter from one form

of trophic existence system to another.

Methanobaterium

Haloarcuta

Haloferox

Halococcus Methano

coccus

Pyrodictium

Desulf urococus

Sufolobus

Thermofilum

Thermoproteus

Pyrobaculum

Archaeglobus

Thermococcus

Euarchaeota Crenarchaeota

Halobacteriales

Thermo

plasmales

Thermo

plasma

Pleurophilus

Ferroglobus

Methano

genales

Thermococcus Pyrococcus

Archaeoglobus

Thermoproteales

Ignaeococcales

Sulfolohales

Fig. 4.19 Phylogenetic tree of the Archae (Modified from
Ciccarelli et al. 2006 )
Note: The genera of Archeae are given above. They are
placed in the two phyla of Archeae which have been cultivated,
Euarchaeota and Crenarchaeota. A third phylum, the

Korarcheota are only known from their DNA sequences and

have not yet been cultivated. The notations in red are orders in

which the genera are grouped. Thus the halophilic archeae are

grouped among the Halobacteriales the methane producers are

in Methagenales