Environmental Engineering Reference
In-Depth Information
monocyte-derived macrophages and can inhibit
the phagocytic response of macrophages even at
low concentration.
Burkholderia plantarii
DSM 9509 has been
demonstrated to be the most prominent rhamno-
lipid producer. According to Hörmann et al.
(
2010
) and Walter (
2009
),
B. plantarii
DSM
9509 produced Rha2-C
14
-C
14
congeners that
reduced the surface tension of water to 29.4 mN
m
−1
with critical micelle concentrations (CMC)
between 15 and 20 mg L
−1
. The maximum rham-
nolipid concentration during 0.5 L bioreactor cul-
tivation was 45.75 mg L
−1
. However, this
organism is a plant pathogen responsible for the
fi re blight disease of apple and pear trees, and the
di-rhamnolipid from
B. plantarii
is an endotoxin
(Mitchell and Teh
2005
). Costa et al. (
2011
) also
showed rhamnolipid concentration of 1 g L
−1
in
B. glumae
AU6208 at 34 °C, 2 % canola oil and
100 mM urea, but this organism is toxic to rice
grain and seedlings.
Renibacterium salmoninarum
is a diplobacil-
lus fastidious bacterium identifi ed as potent bio-
surfactant producer on n-hexadecane as a carbon
source (Christova et al.
2004
). It is also interest-
ing to know that this bacterium produces the two
typical rhamnolipid as in
P. aeruginosa
and has
the potential of being useful in natural degrada-
tion of hydrophobic pollutants due to its high cell
hydrophobicity. Despite these promising charac-
teristics, this organism has raised a signifi cant
ecological concern. It causes a haemorrhagic
infection known as bacterial kidney infection
(BKD) or salmonid kidney disease in young sal-
monid fi sh (Wiens et al.
2008
).
with maximum production of 21 g L
−1
in 24 h on
glucose, fructose and sucrose. However,
Pantoea
sp. have recently been consistently linked with
infections in humans (wound, blood, soft tissue,
bone and urinary tract infections) and plants (Da
Baere et al.
2004
; Fullerton et al.
2007
; Kratz
et al.
2003
). These organisms have also been
associated with bacteraemia outbreaks in many
patients through their contact with contaminated
cotton pledgets (Koo et al.
2006
; Silvi et al.
2013
).
Production of glycolipid biosurfactant has
been reported for
Nocardia otitidiscaviarum
, a
marine strain. The biosurfactant possessed
increased cell hydrophobicity, making it very
potent for bioremediation of oil-polluted sites
(Vyas and Dave
2011
). Recently, these bacterial
species have been identifi ed as causative agents
in a couple of clinical infections ranging from
pulmonary nocardiosis, brain abscess and actino-
mycetoma (Pelaez et al.
2009
; Chi et al.
2013
).
Alcaligenes faecalis
has been reported by
Bharali et al. (
2011
) as a producer of biosurfac-
tant exhibiting excellent surface activity using
different hydrocarbon substrates. However,
A.
faecalis
is a known pathogen infecting human
and domesticated birds such as chickens and tur-
keys (Simmons et al.
1981
). Kaliaperumal et al.
(
2006
) reported
A. faecalis
as the causative agent
in post-operative endophthalmitis in human eye
resulting in symptoms such as swelling of the
eyelid, redness and permanent loss of vision.
In addition, Kahveci et al. (
2011
) have reported a
link between the developments of peritonitis
to contamination of catheters by
A. faecalis
.
The pathogenic mechanism of this microbe is
largely unknown.
Rosenberg et al. (
1989
) identifi ed
Acinetobacter
calcoaceticus
A2 as a producer of an extracellu-
lar anionic surfactant referred to as biodispersan
or emulsan which is a high molecular weight bio-
surfactant. Pirog et al. (
2009
) have also reported
the production of low molecular weight biosur-
factant by
A. calcoaceticus
IMV B-7241 which
was confi rmed to be trehalose mycolates by
enzymatic studies.
A. calcoaceticus
has been
described as a commensal in humans but is also
responsible for many clinical infections as an
opportunistic pathogen. These infections include
2.2
Glycolipids and Trehalose
Mycolates
Glycolipid production by other known pathogens
has been reported. The Antarctic facultative
anaerobe
Pantoea agglomerans
is a biosurfactant
producer with hydrocarbon compounds (hexane,
kerosene and paraffi n) as growth substrates
(Vasileva-Tonkova and Gesheva
2007
; Jacobucci
et al.
2009
).
Pantoea
sp. has also been reported as
producers of high levels of exopolysaccharides
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