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The name Acinetobacter comes from
the translation of a scientific Greek word, and it means nonmotile/immobile
Members of the genus Acinetobacter are gram-negative,
nonmotile, strictly aerobic, oxidase-negative coccobacilli. The bacteria of the
genus do not make spores. Acinetobacter species are found in soil and water,
sewage, human clinical specimens, and activated sludge. (Yoon et al., 2007).
marinus is a slightly halophilic bacterial strain of the genus Acinetobacter.
The genus is known to cause
diseases in hospitals, especially in intensive care units.
Acinetobacter genus bacteria are ubiquitous,
free-living, gram-negative, saprophytic bacilli. The members of the genus are
also prevalent in the clinical environment, and can be easily isolated from the
skin of hospital patients and doctors where they can exist as commensals or
pathogens (Towner, 1997).
Acinetobacter can survive for a long
time on human skin as well as on hospital equipment. (Towner, 1997). The
members of the genus can develop resistance to major groups of antibiotics.
Combination therapy is usually required as part of treatment (Bergogne-Bérézin & Towner, 1996).
There have been reported cases of
community-acquired diseases cause by the species of the genus Acinetobacter, but
those are rare.
Acinetobacter species engage in a symbiotic relationship with different insect species. Acinetobacter genus bacteria inhabit
the midgut of the tsetse flies, Glossina
palpalis and Glossina pallicera. The complete development of the Stomoxys calcitrans fly larvae requires the presence of Acinetobacter spp. (Soumana et
Moreover, Acinetobacter spp.
were found in the gut of the tobacco hornworm, Manduca sexta, when the insect was raised on a diet containing
antibiotics (Van der Hoeven et al., 2008).
Acinetobacter are also known to colonize the cadaver of the moth species Galleria mellonella larvae
infected by the Steinernema nematode
species. The studies also show that the bacteria are associated with the
nematode, and do not originate in the insect, since there is no evidence for
the presence of Acinetobacter in the
digestive gut of the Galleria (Walsh & Webster, 2003).
The members of the genus
Acinetobacter are generally nonmotile. However, Acinetobacter baumannii show twitching motility on Lysogeny broth (LB) agar plates with agar concentrations between 0.2 and 0.4 %. The motility varies depending on the type of agar used (Clemmer et al., 2011).
The members of the genus
Acinetobacter are known to cause a variety of nosocomial, or hospital-acquired
infections, which include bacteraemia, secondary meningitis, urinary tract
infections, and nosocomial pneumonia, particularly ventilator-associated
pneumonia, in intensive care units (Towner, 1997).
marinus is not known to cause any diseases in humans or other animals.
Studies of A. marinus have yielded a nearly complete sequence of the
bacteria’s 16S rRNA (Yoon et al, 2006).
marinus shows 94.4% similarity of 16S rRNA sequence with A. calcoaceticus,
and 96.5% similarity with A. grimontii.
Acinetobacter species are found in
soil and water, sewage, human clinical specimens, and activated sludge. The
bacteria of the genus are capable of long-term survival on human skin and
marinus was found in the Yellow Sea in Korea (Yoon et al., 2006).
Acinetobacter marinus can be grown on
marine agar; it has an optimum temperature range of between 30-37 ˚C. Other free-living members of
the genus can be grown on either nutrient agar or nutrient broth.
Acinetobacter marinus has an
optimum pH level between 6.0-8.0.
The DNA GC content is 44.1%.
Colonies of strain A. marinus on marine
agar are circular, smooth, glistening, slightly convex, milky-white in color,
and 0.8-1.0 mm in diameter after 3 days of incubation at 30˚C. Colonies of
strain A. marinus on nutrient agar are circular to slightly irregular, smooth,
glistening, raised, cream-colored, and 2.0-4.0 mm in diameter after 3 days of
incubation at 30˚C (Yoon, 2007).
Acinetobacter are gram-negative
bacteria. They are nonmotile, strictly aerobic, oxidase-negative coccobacilli.
A. marinus is a slightly halophilic bacterial strain, which means it prefers
environments with high salinities.
In general, Acinetobacter species
are known for their antibiotic and multi-drug resistance. However, due to very
limited data on the species, there is no information on A. marinus being
resistant to any drugs.
A. marinus can grow in the temperature
range of 10-40˚C with an optimum temperature between 30 and 37 ˚C.
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