Biosurfactants and Bioemulsifiers from Marine Sources - Biosurfactants: Research Trends and Applications - page 130

The fatty acid moiety comprises one or two fatty acids with a chain length of C 6 -C 20
with or without unsaturation depending on the source of the fatty acid and the
microbial enzyme involved in processing the fatty acid part of the BS. Glycolipid-
producing microbes were isolated from different marine sources such as Halomonas
sp. ANT-3b isolated from Ross Sea, Antarctica (Pepi et al., 2005), which produced
a glycolipid BS with a molecular weight of 18 kDa using n -hexadecane as the sole
carbon source. P. aeruginosa A41 isolated from the gulf of Thailand was capable
of utilizing wide range of carbon sources (oil, lauric acid, myristic acid, palmitic
acid, stearic acid, oleic acid, and linoleic acid) and produced 6.58 g/L rhamnolip-
ids with olive oil as the carbon substrate (Thaniyavarn et al., 2006). Azotobacter
chroococcum, Bacillus megaterium, and Lactobacillus delbrueckii isolated from
Tuticorin coastal waters (Tamil Nadu, India) using crude oil as the carbon source
produced glycolipid BSs on crude oil, waste motor oil, and peanut oil cake carbon
sources (Thavasi et al., 2006, 2008, 2011a). The highest BS production was observed
with peanut oil cake as 4.6, 1.4, and 5.3 g/L, respectively, and was able to emulsify
a wide range of hydrocarbons and vegetable oil in the order of waste motor lubricant
oil > crude oil > peanut oil > kerosene > diesel > xylene > anthracene > naphthalene.
Among the glycolipid BSs, trehalose lipids, trehalose corynomycolates, and treha-
lose tetraester are the second largest group reported (9%). Trehalose lipid production by
an Antarctic Rhodococcus fascians DSM 20669 strain was reported by Yakimov et al.
(1999), and the surfactant reduced the surface tension of water from 72 to 32 mN/m.
Trehalose tetraester production was found with n -alkanes utilizing marine bacterium,
Arthrobacter sp. EK1 (Passeri et al., 1991). The main fraction of the purified surfactant
is an anionic 2,3,4,2′-trehalose tetraester. The chain lengths of fatty acids ranged from
8 to 14. Trehalose corynomycolates producing marine Arthrobacter sp. SI1 was iso-
lated from North Sea, and it produced 2 g/L of BS. The isolated BSs showed significant
interfacial and emulsifying properties (Schulz et al., 1991).
A marine sponge associated Aspergillus sp. MSF1 strain producing rhamnolip-
ids was also isolated from the Bay of Bengal coast of India (Kiran et al., 2010c).
Rhamnolipid BS isolated from Aspergillus sp. MSF1 showed potential activity against
pathogenic yeast, Candida albicans and bacteria, Streptococcus sp. , Micrococcus
luteus , and Enterococcus faecalis . Konishi et al. (2010) recently isolated a mannosyl-
erythritol lipid-producing Pseudozyma hubeiensis from a deep sea clam Calyptogena
soyoae at 1156 m in Sagami Bay. The major component of the BS was MEL-C
(4 -o-[4′-o-acetyl-2′,3′-di-o-alka(e)noil-β-d-mannopyranosyl]-d-erythritol). Analysis
of the lipid part of the BS revealed that major fatty acids of MEL-C were saturated
fatty acids with chain lengths of C 6 , C 10 , and C 12 . The surface tension determination of
the MEL-C showed a critical micelle concentration (CMC) of 1.1 × 10 −5 M.
Another class of BSs that are not in the spotlight of general research is
glycoglycerolipids. There are three reports available on glycoglycerolipids from
marine bacterial strains. The marine bacterium Microbacterium sp. DSM 12583,
isolated from the Mediterranean sponge Halichondria panicea , was able to form
a glucosylmannosyl-glycerolipid (GGL 2), 1-o-acyl-3-[α-glucopyranosyl-(1-3)-
(6-o-acyl-α-mannopyranosyl)]glycerol, when grown on a complex medium
with glycerol (Wicke et al., 2000). Another marine strain, M. luteus was isolated
from the North sea and reported to produce a dimannosyl-glycerolipid (GGL 5),