Environmental Engineering Reference
In-Depth Information
Ta b l e 1
(continued)
Environmental
Parameters
Types
Definition
Examples
References
Mesophilic-
peizophiles
15 MPa
Desulfovibrio profundus
[4]
60 MPa
Pseudomonas sp. Ms300
[51]
Desiccation
Xerophiles
Anhydrobiotic
Artemia salina ;
Nematodes
Microbes, Fungi, Lichens
[84]
[79]
Salinity
Halophiles
Salt loving
(2-5 M Nacl)
Haloarcula,
Halobacterium,
Haloferax,
Halorubrum,
Dunaliella salina
[61]
pH
Alkaliphiles
pH>9
Natronobacterium,
Natronococcus,
Bacillus firmus OF4,
Spirulina sp. (all pH 10.5)
[61]
Acidophiles
pH<4
Ascidianus, Desulfurolobus,
Sulfolobus, Thiobacillus,
Cyanidium caldarium,
Ferroplasma sp.
[61]
O 2 Tensions
Anaerobes
Micro-aerophiles
Aerobe
Cannot tolerates O 2
Tolerates some O 2
Require O 2
Methanococcus jannaschii
Clostridium
H. sapiens
[41]
[67]
[61]
Chemical
extremes
Heavy metals and
gases
Can tolerate high
concentation of
metals and gases
Cyanidium caldrium
(pure CO 2 ), Feroplasma,
Acidarmus (Cu,As,Cd and
Zn), Ralstinia sp.
CH34(Zn,Co,Cd,Hg,Pb)
[61]
2.1 Factors Influencing Extremophilism
2.1.1 Temperature
Temperature creates a series of challenges to the living forms, from the structural
destruction by formation of ice crystals at the freezing point to the denaturation of
biomolecules at the higher temperature. The solubility of different gases in water
is largely depending on the temperature, creating problems at high temperature for
aquatic organisms requiring oxygen or carbon-dioxide for their metabolic processes.
Increases in temperature up to 100 C, denatures bio-molecules including functional
and structural proteins and nucleic acids. Natural thermal tolerance ranges (Fig. 1)
from hyper-thermophilic (maximum growth >80 C) to psychrophilic (maximum
growth <15 C) has been reported [61].
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