Environmental Engineering Reference
In-Depth Information
urinary tract infection, pneumonia, respiratory
tract infection and post-operative infections
(Pal and Kale
1981
).
surfactant reduced the surface tension of water
from 72 to 28.70 mN m
−1
. However, this bacte-
rium cannot stand the chance of being used for
industrial-scale production of biosurfactant due
to its pathogenicity. Most importantly, serrawettin
biosurfactant is a virulence factor, and
S. marcescens
strains have been linked with a number of
infections including nosocomial infections bac-
teraemia, urinary tract infections, meningitis and
endocarditis (Anyanwu et al.
2010
; Körner et al.
1994
). According to a report by the Centers for
Disease Control in the USA,
S. marcescens
was
confi rmed as the main causative organism in the
Alabama hospital outbreaks that happened in
2011 affecting 19 patients with 10 deaths.
Saimmai et al. (
2013
) identifi ed a Gram-
negative bacterium
Inquilinus limosus
KB3
capable of producing lipopeptide biosurfactant
using palm oil cake as a carbon source. The bio-
surfactant reduced the surface tension of water
from 72 to 25.5 mN m
−1
with a maximum yield
of 5.13 g L
−1
and CMC at 9 mg L
−1
. The genus
Inquilinus
was fi rst defi ned in 2002 based on the
molecular analysis of 51 unknown cystic fi brosis
isolates. This group of organisms is unrelated to
P. aeruginosa
and
B. cepacia. Inquilinus limosus
has been reported as a multidrug-resistant pathogen
and has been isolated from the lungs of cystic
fi brosis patients (Wellinghausen et al.
2005
;
Hayes et al.
2009
).
2.3
Phospholipids
and Lipopeptides
Biosurfactant production by a prominent member
of the
Klebsiella
genus known as
Klebsiella
pneumoniae
has been identifi ed. According to
Jamal et al. (
2012
),
Klebsiella pneumoniae
WMF02 showed increased biosurfactant produc-
tion after medium optimisation with a maximum
yield of 85 g L
−1
and surface tension reduction of
25.70 mN m
−1
compared to the non-optimised
medium (36.2 mN m
−1
). This organism has shown
the promising potential of a good biosurfactant
producer, but its application will involve certain
health and safety risks.
K. pneumoniae
is a sig-
nifi cant human pathogen causing different
destructive effects to the human upper and lower
respiratory tracts if inhaled which includes pneu-
monia and bronchitis. Other notable infections
caused by this organism include diarrhoea,
wound infections, osteomyelitis, meningitis, bac-
teraemia and septicaemia (Ryan and Ray
2004
).
Recently, these bacterial strains have been
reported as resistant to antibiotics especially car-
bapenem antibiotics (Limbago et al.
2012
). They
have also been associated with a chronic infl am-
matory spinal and large joint arthritic condition
known as ankylosing spondylitis (AS) affecting
young-aged males (Rashid and Ebringer
2007
).
Serratia marcescens
is a multidrug-resistant
pathogen causing infections in different hosts
ranging from plants, animals and humans. This
bacterium produces a lipopeptide biosurfactant
known as serrawettin (Dusane et al.
2011
). The
biosurfactant is very potent and has been reported
in literature to reduce the surface tension of water
from 72 to 37 mN m
−1
, emulsifying kerosene and
diesel with a maximum emulsion index of 72 %
and 40 %, respectively (Wei et al.
2004
). Ferraz
et al. (
2002
) also reported biosurfactant produc-
tion by
S. marcescens
strains. The biosurfactant
reduced the surface tension of the culture medium
from 64.54 to 29.57 mN m
−1
, while the crude bio-
2.4
Heteropolysaccharides
Jain et al. (
2012
) reported the production of a het-
eropolysaccharide biosurfactant by an alkaliphi-
lic bacterium,
Cronobacter sakazakii
, formerly
known as
Enterobacter sakazakii
. The biosurfac-
tant comprised of total sugars (73.3 %), reducing
sugars (1.464 %), protein (11.9 %), uronic acid
(15.98 %) and sulphate (6.015 %). The monosac-
charide moieties in this biosurfactant were
revealed by GC-MS as glucose (14 %), mannose
(24 %), galactose (14 %), xylose (20 %) and
arabinose (19 %). The extracted biosurfactant
from this bacterium effi ciently emulsifi ed aliphatic
and aromatic hydrocarbons forming stable emul-
sions in the presence of xylene, cyclohexane,
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