siderophores, it may be rewarding to further study alkaliphiles as sources of novel
siderophores that are amenable for different applications.
4.5 Biosurfactant Production by Alkaliphiles
Biosurfactants are surface-active amphiphilic biomolecules produced by plants and
microorganisms. These surface-active agents are more efficient, and their critical
micelle concentration (CMC) is 10–40 times lower than that of chemical surfactants
CMC [191]. The low CMC values indicate that it is possible to reduce the surface
tension effectively using very low amount of biosurfactants. In general, their unique
properties such as low toxicity, high efficiency, better environmental compatibility,
higher stability, etc. have brought interest on biosurfactants. Some of which have got
their ways into a range of applications such as in chemical, petroleum, mining,
agrochemical, fertilizer, food, beverage, cosmetic and pharmaceutical industries.
Biosurfactants are used as foaming agents, emulsifiers, demulsifiers, wetting agents,
spreading agents, functional food ingredients, and detergents [192]. The global
biosurfactant market is expanding at a reasonable pace. For the year 2018, the
market was estimated to be about USD 4.2 billion, and in year 2026 it is forecasted
to reach USD 7.25 billion [193]. The demand for green products in personal and
home care industries seems to be the major impetus for the market growth.
Several microorganisms have been isolated and studied for surfactant production.
Among alkaliphiles, strains of Cronobacter sakazakii [194], Achromobacter
xylosoxidans [195], Exiguobacterium [196], Natronolimnobius innermongolicus
[197], Ochrobactrum intermedium [198] are proven surfactant producers. As
biosurfactants produced by alkaliphiles are believed to have evolved to work at
high pH conditions, biosurfactants of alkaliphilic origin may be of special interest to
applications that involve high pH conditions such as detergents and oil extraction.
Characterization studies made on surfactants from alkaliphiles revealed interesting
results. The biosurfactants from a haloalkaliphilic archaea is stable in pH range of
5–12 and high salinity (up to 35% (w/v)) [197]. The surfactant produced by
Klebsiella sp. RJ-03 is found to be compatible to detergents and effective for
enhanced oil recovery [194]. The Ochrobactrum intermedium biosurfactants have
shown remarkable stability at pH 10–13 and up to 90
C [198]. These interesting
properties such as operational stability at high pH, temperature, and salinity indicate
the potential of alkaliphiles to become sources of excellent biosurfactants.
4.6 Exopolysaccharides of Alkaliphiles
Microbial exopolysaccharides (EPSs) are high molecular weight sugar-containing
substances secreted by microorganisms. These substances contain distinct monosaccharide units as well as non-carbohydrate substituents and are often species specific.
Alkaliphiles: The Versatile Tools in Biotechnology
25
siderophores that are amenable for different applications.
4.5 Biosurfactant Production by Alkaliphiles
Biosurfactants are surface-active amphiphilic biomolecules produced by plants and
microorganisms. These surface-active agents are more efficient, and their critical
micelle concentration (CMC) is 10–40 times lower than that of chemical surfactants
CMC [191]. The low CMC values indicate that it is possible to reduce the surface
tension effectively using very low amount of biosurfactants. In general, their unique
properties such as low toxicity, high efficiency, better environmental compatibility,
higher stability, etc. have brought interest on biosurfactants. Some of which have got
their ways into a range of applications such as in chemical, petroleum, mining,
agrochemical, fertilizer, food, beverage, cosmetic and pharmaceutical industries.
Biosurfactants are used as foaming agents, emulsifiers, demulsifiers, wetting agents,
spreading agents, functional food ingredients, and detergents [192]. The global
biosurfactant market is expanding at a reasonable pace. For the year 2018, the
market was estimated to be about USD 4.2 billion, and in year 2026 it is forecasted
to reach USD 7.25 billion [193]. The demand for green products in personal and
home care industries seems to be the major impetus for the market growth.
Several microorganisms have been isolated and studied for surfactant production.
Among alkaliphiles, strains of Cronobacter sakazakii [194], Achromobacter
xylosoxidans [195], Exiguobacterium [196], Natronolimnobius innermongolicus
[197], Ochrobactrum intermedium [198] are proven surfactant producers. As
biosurfactants produced by alkaliphiles are believed to have evolved to work at
high pH conditions, biosurfactants of alkaliphilic origin may be of special interest to
applications that involve high pH conditions such as detergents and oil extraction.
Characterization studies made on surfactants from alkaliphiles revealed interesting
results. The biosurfactants from a haloalkaliphilic archaea is stable in pH range of
5–12 and high salinity (up to 35% (w/v)) [197]. The surfactant produced by
Klebsiella sp. RJ-03 is found to be compatible to detergents and effective for
enhanced oil recovery [194]. The Ochrobactrum intermedium biosurfactants have
shown remarkable stability at pH 10–13 and up to 90
C [198]. These interesting
properties such as operational stability at high pH, temperature, and salinity indicate
the potential of alkaliphiles to become sources of excellent biosurfactants.
4.6 Exopolysaccharides of Alkaliphiles
Microbial exopolysaccharides (EPSs) are high molecular weight sugar-containing
substances secreted by microorganisms. These substances contain distinct monosaccharide units as well as non-carbohydrate substituents and are often species specific.
Alkaliphiles: The Versatile Tools in Biotechnology
25