in salt lakes and in salted fish and turn lakes and fish red when there is
an abundance of Extreme halophiles.- Halobacterium salinarium. Halobacterium salinarium is an archaea that
acquires energy through photosynthesis. However, it is able to do so with-
out the need of chlorophyll or bacteriochlorophyll. Halobacterium sali-
narium synthesizes the bacteriorhodopsinprotein,which shows as a deep
purple color under high-intensity lighting in a low-oxygen environment. - Thermophilic archaeon. Thermophilic archaeons are known as thermo-
plasma and grow in hot (55 to 59 degrees Celsius), acidic (pH of
1 to 2) refuse piles of coalmines that contain iron pyrite. These refuse
piles become hot and acidic as chemolithotropic bacteria oxidize iron
pyrite into sulfuric acid. Thermophilic archaeons lack a cell wall. - Sulfate-reducing archaea. Sulfate-reducing archaea are known as
archaeoglobiand extract electrons from various donors to reduce sulfur
to sulfide in an environment that is approximately 83 degrees Celsius
such as near marine hydrothermal vents (underwater hot springs).
Sulfate-reducing archaea are gram-negative and are shaped as irregular
spheres (coccoid cells).
Aerobic/Microaerophilic, Motile, Helical/Vibroid,
Gram-Negative Bacter ia
Another kind of prokaryote is the aerobic/microaerophilic, motile, helical/vibroid,
gram-negative bacterium. This is a mouthful to say, but the name describes char-
acteristics of this group of prokaryote bacteria.
Aerobic/microaerophilicmeans bacteria within this group require small amounts
of oxygen to grow. Motileimplies that the bacterium is self-propelled, using fla-
gella at one or both poles to move in a corkscrew motion. Helical/vibroidindicates
that the bacterium takes the shape of a spiral (helical) or as a curved rod (vibroid).
Gram-negative means that when the bacterium is identified using the Gram stain,
the bacterium loses the violet stain when rinsed and appears red or pink.
Aerobic/microaerophilic, motile, helical/vibroid, gram-negative bacteria thrive
in soil and are found on roots of plants such as the Azospirillum, which improves
a plant’s nutrient uptake. Bacteria within this group are also found in both fresh
and stagnant water.
Some aerobic/microaerophilic, motile, helical/vibroid, gram-negative bacte-
ria cause diseases (pathogenic) such as Campylobacter fetusand Campylobacter(^154) CHAPTER 10 The Prokaryotes