Biosurfactant usually refers to

surfactant Surfactants are chemical compounds that decrease the surface tension or interfacial tension between two liquids, a liquid and a gas, or a liquid and a solid. The word ''surfactant'' is a Blend word, blend of "surface-active agent", coined in ...

s of microbial origin. Most of the biosurfactants produced by microbes are synthesized extracellularly and many microbes are known to produce biosurfactants in large relative quantities. Some are of commercial interest. As a secondary metabolite of microorganisms, biosurfactants can be processed by the cultivation of biosurfactant producing microorganisms in the stationary phase on many sorts of low-priced substrates like

biochar Biochar is a form of charcoal, sometimes modified, that is intended for organic use, as in soil. It is the lightweight black remnants remaining after the pyrolysis of biomass, consisting of carbon and ashes. Despite its name, biochar is steril ...

, plant oils, carbohydrates, wastes, etc. High-level production of biosurfactants can be controlled by regulation of environmental factors and growth circumstances.

Classification

Biosurfactants are usually categorized by their molecular structure. Like synthetic surfactants, they are composed of a hydrophilic moiety made up of amino acids, peptides, (poly)saccharides, or sugar alcohols and a hydrophobic moiety consisting of fatty acids. Correspondingly, the significant classes of biosurfactants include glycolipids, lipopeptides and lipoproteins, and polymeric surfactants as well as particulate surfactants.

Examples

Common biosurfactants include: *

Bile salts Bile acids are steroid acids found predominantly in the bile of mammals and other vertebrates. Diverse bile acids are synthesized in the liver in peroxisomes. Bile acids are conjugated with taurine or glycine residues to give anions called bile ...

are mixtures of micelle-forming compounds that encapsulate food, enabling absorption through the small intestine. *

Lecithin Lecithin ( ; from the Ancient Greek "yolk") is a generic term to designate any group of yellow-brownish fatty substances occurring in animal and plant tissues which are amphiphilic – they attract both water and fatty substances (and so ar ...

, which can be obtained either from soybean or from egg yolk, is a common food ingredient. *

Rhamnolipid Rhamnolipids are a class of glycolipid produced by ''Pseudomonas aeruginosa ''Pseudomonas aeruginosa'' is a common Bacterial capsule, encapsulated, Gram-negative bacteria, Gram-negative, Aerobic organism, aerobic–facultative anaerobe, faculta ...

s, which can be produced by some species of ''

Pseudomonas ''Pseudomonas'' is a genus of Gram-negative bacteria belonging to the family Pseudomonadaceae in the class Gammaproteobacteria. The 348 members of the genus demonstrate a great deal of metabolic diversity and consequently are able to colonize a ...

'', e.g., ''

Pseudomonas aeruginosa ''Pseudomonas aeruginosa'' is a common Bacterial capsule, encapsulated, Gram-negative bacteria, Gram-negative, Aerobic organism, aerobic–facultative anaerobe, facultatively anaerobic, Bacillus (shape), rod-shaped bacteria, bacterium that can c ...

''. * Sophorolipids are produced by various nonpathogenic yeasts. * Emulsan produced by ''Acinetobacter calcoaceticus''. *

Surfactin Surfactin is a cyclic lipopeptide, commonly used as an antibiotic for its capacity as a surfactant. It is an amphiphile capable of withstanding hydrophilic and hydrophobic environments. The Gram-positive bacterial species ''Bacillus subtilis' ...

is a non-ribosomal lipopeptide produced by ''

Bacillus subtilis ''Bacillus subtilis'' (), known also as the hay bacillus or grass bacillus, is a gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants, humans and marine sponges. As a member of the genus ''Bacill ...

'' Microbial biosurfactants are obtained by including immiscible liquids in the growth medium.

Applications

Potential applications include herbicides and pesticides formulations, detergents, healthcare and cosmetics, pulp and paper, coal, textiles, ceramic processing and food industries, uranium ore-processing, and mechanical dewatering of peat.

Oil spill remediation

Biosurfactants enhance the emulsification of hydrocarbons, thus they have the potential to solubilise hydrocarbon contaminants and increase their availability for microbial degradation. In addition, biosurfactants can modify the cell surface of bacteria that biodegrade hydrocarbons, which can also increase the biodegradability of these pollutants to cells. These compounds can also be used in

enhanced oil recovery Enhanced oil recovery (abbreviated EOR), also called tertiary recovery, is the extraction of crude oil from an oil field that cannot be extracted after primary and secondary recovery methods have been completely exhausted. Whereas primary and se ...

and may be considered for other potential applications in environmental protection.

References

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External links

Production and Characterization of Biosurfactants Using Bacteria Isolated from Acidic Hot Springs
Surfactants Bioremediation Cleaning product components Environmental terminology