Call us  +919820570188

408, Archana Building, Sector 17, Vashi, Navi Mumbai - 400703 INDIA. E-mail: [email protected]

Developments in Biosurfactants

Abstract

Consumers’ market is growing. Our search for ecofriendly products continues. It is no wonder that interest in research and commercialization of biogums, biosurfactants, bioflocculants, bioadhesives is growing. Increasing awareness among consumers for bio-based products will give rise to new markets for the biosurfactants. However, lack of cost competitiveness of biosurfactants remains a major concern.

Introduction

Biosurfactant production and analysis is currently a wide and active field of study. As of 2006 there were 255 patents granted to biosurfactants and bioemulsifier compounds. Commercial interests in the applications of biosurfactants are increasing.

Surfactants are chemicals that reduce the surface tension of water. Surfactants are widely used in soaps, laundry detergents, dishwashing liquids, personal care products, such as shampoos, in lubricants, emulsion polymerization, textile processing, mining flocculates, petroleum recovery, and wastewater treatment. Most currently used surfactants are derived from petroleum feedstocks. The annual global production of surfactants was 13 million metric tons in 2008, and the annual turnover reached US$24.33 billion in 2009, nearly 2% up from the previous year. The market is expected to experience quite healthy growth by 2.8% annually to 2012 and by 3.5 – 4% thereafter. Specialists expect the global surfactant market to generate revenues of more than US$41 billion in 2018 – translating to an average annual growth of 4.5%.

Indian surfactant consumption was just over 500,000 tons as of 2011. The Indian market is dominated by Galaxy Surfactants, with Godrej, Reliance and Clariant being some key participants.

Many of these chemical surfactants pose significant environmental risks because they form harmful compounds from incomplete biodegradation in water or soil.

The global biosurfactants market volume is expected to be 476,512.2 tons by 2018. Out of this total, 21% of volume consumption will come from developing regions such as Asia, Africa and Latin America.

Biosurfactants are not only superior ecofriendly replacements for chemical surfactants but also have several applications in many areas of human interest. Once the production economics for biosurfactants improves they will find increased use in various applications. Less expensive substrates, and better techniques of product recovery are required to improve production economics of biosurfactants.

Global biosurfactants market was worth USD 1,735.5 million in 2011 and is expected to reach USD 2,210.5 million in 2018, growing at a CAGR of 3.5% from 2011 to 2018. In the overall global market, European region is expected to maintain its lead position in terms of volume and revenue till 2018. Europe is expected to enjoy 53.3% of global biosurfactants market revenue share in 2018 followed by North America.

A number of renowned surfactants vendors such as BASF-Cognis and Ecover have already ventured into the biosurfactants market. BASF-Cognis leads the pack with over 20% share of the market in 2011. Other major producers include Ecover, Urumqi Unite, Saraya and MG Intobio. The top three biosurfactants vendors accounted for more than 60% of the market share in 2011.

Surfactants and Biosurfactants

Surfactants are amphipathic molecules with both hydrophilic and hydrophobic (generally hydrocarbon) moieties. Well-known synthetic surfactants are used for a wide variety of purposes, such as emulsification, foaming, detergency, solubilization, wetting and spreading. Almost all surfactants currently in use are chemically derived from petroleum. However, the interest in microbial surfactants has been steadily increasing in recent years due to their diversity, environmentally friendly characteristics, the possibility of their production through fermentation and their potential applications in such areas as the environmental protection, crude oil recovery, health care and the food-processing industries. Biosurfactants are a structurally diverse group of surface-active molecules synthesized by micro-organisms.

Surfactants may be nonionic, cationic, anionic, amphoteric in nature. Most commonly, surfactants are classified according to polar head group. A non-ionic surfactant has no charge groups in its head. The head of an ionic surfactant carries a net charge. If the charge is negative, the surfactant is more specifically called anionic; if the charge is positive, it is called cationic. If a surfactant contains a head with two oppositely charged groups, it is termed zwitterionic.

World production of surfactants is estimated at 15 Mton/y, of which about half are soaps. Other surfactants produced on a particularly large scale are linear alkylbenzenesulfonates (1700 kton/y), lignin sulfonates (600 kton/y), fatty alcohol ethoxylates (700 ktons/y), alkylphenol ethoxylates (500 kton/y).

Synthetic surfactants (chemically produced) are reported to cause adverse effects on long term use whereas biosurfactants do not have so. Synthetic surfactants have high degree of branching which causes poor degradability while biosurfactants are readily biodegradable making them environmentally compatible. Unlike most synthetic surfactants, biosurfactants show good activity at extreme conditions of pH, temperature and salinity. Biosurfactants produced by some bacteria and yeast also show antimicrobial activity.

Lack of cost competitiveness of biosurfactants remains a major concern. Consumers’ market is growing. Increasing awareness among consumers for bio-based products will give rise to new markets for the biosurfactants. Moreover, awareness created by regulatory organizations will also support the growth of biosurfactants market.

Among all the segments, the household detergents and personal care segment together will be the point of focus contributing more than 56.8% of the global biosurfactants market in 2018. Europe is leading globally in terms of production and consumption of biosurfactants, followed by North America, mainly due to recovering economies and increasing income and expenditure on consumer goods.

Biosurfactants are surface-active substances synthesized by living cells. They have the properties of reducing surface tension, stabilizing emulsions, promoting foaming and are generally non-toxic and biodegradable. Interest in microbial surfactants has been steadily increasing in recent years due to their (i) diversity, (ii) environmentally friendly nature, (iii) possibility of large-scale production, (iv) selectivity, (v) performance under extreme conditions and (vi) potential applications in environmental protection.

Biosurfactants are amphiphilic compounds produced on living surfaces, mostly microbial cell surfaces, or excreted extracellularly and contain hydrophobic and hydrophilic moieties that reduce surface tension and interfacial tensions between individual molecules at the surface and interface, respectively. Biosurfactants are also bioemulsifiers.

Biosurfactants are a group of structurally diverse molecules produced by different microorganisms classified mainly by their chemical structure and microbial origin. Structurally, they contain a hydrophilic moiety, comprising an acid, peptide cations, or anions, mono-, di- or polysaccharides and a hydrophobic moiety of unsaturated or saturated hydrocarbon chains or fatty acids. They are mainly classified into two classes: low-molecular weight surface active agents called biosurfactants (lipopeptide, glycolipids) and bioemulsifiers (high molecular weight surface active agents). They efficiently reduce surface and interfacial tensions. Biosurfactants are further divided into six classes: hydroxylated and cross linked fatty acids (mycolic acids), glycolipids, lipopolysaccharides, lipoproteins-lipopeptides, phospholipids and the complete cell surface itself.

Biosurfactants are amphiphilic compounds. They contain a hydrophobic and hydrophilic moiety. The hydrophilic (polar) moiety (water soluble) can be a carbohydrate, an amino acid or peptide, a phosphate group, alcohol, carboxylic acid or some other compound. Glycolipids and Lipopeptides are low molecular weight biosurfactants. The hydrophobic (nonpolar) moiety (oil soluble) is mostly a long-carbon-chain fatty acid (saturated or unsaturated). Hydrophilic and hydrophobic moieties partition preferentially at interface between fluid phases with different degrees of polarity and hydrogen binding such as oil/water air/water interface. These properties make surfactants capable of reducing surface and interfacial tension and foaming microemulsion where hydrocarbons can solubilize in water or where water can solubilize in hydrocarbon. This confers detergency, emulsifying and foaming and dispersing capacity.

The properties ⁄ applications of biosurfactants includes excellent detergency, emulsification, foaming, dispersing traits, wetting, penetrating, thickening, microbial growth enhancement, metal sequestering and resource recovering (oil) which allows biosurfactants an ability to replace some of the most versatile process chemicals.

Like synthetic surfactants, biosurfactants are excellent emulsifiers and maintain wetting and foaming properties which are valuable in applications in cosmetic industry.

The most active biosurfactants can lower the surface tension of water from 72 to 30 mN·m−1 and the interfacial tension between water and n-hexadecane from 40 to 1 mN·m−1.

Biosurfactant activities depend on the concentration of the surface-active compounds until the critical micelle concentration (CMC) is obtained. At concentrations above the CMC, biosurfactant molecules associate to form micelles, bilayers and vesicles.

Micelle formation enables biosurfactants to reduce the surface and interfacial tension and increase the solubility and bioavailability of hydrophobic organic compounds. The CMC is commonly used to measure the efficiency of surfactant. Efficient biosurfactants have a low CMC, which means that less biosurfactant is required to decrease the surface tension. Micelle formation has a significant role in microemulsion formation. Microemulsions are clear and stable liquid mixtures of water and oil domains separated by monolayer or aggregates of biosurfactants. Microemulsions are formed when one liquid phase is dispersed as droplets in another liquid phase, for example oil dispersed in water (direct microemulsion) or water dispersed in oil (reversed microemulsion).

The biosurfactant effectiveness is determined by measuring its ability to change surface and interfacial tensions, stabilization of emulsions and by studying its hydrophilic-lipophilic balance (HLB). The HLB value is a measure to indicate whether a biosurfactant is related to water-in-oil or oil-in-water emulsion. This factor can be used to determine the suitable applicability of biosurfactants. Emulsifiers with low HLB are lipophilic and stabilize water-in-oil emulsification, whereas emulsifiers with high HLB have the opposite effect and confer better water solubility.

Different functions exhibited by biosurfactants are –

(1) Emulsification (2) Deemulsification (3) wetting, spreading, penetration (4) Solubilization and solid dispersal (5) Air entrapment, foaming (6) Detergent (7) Defoaming (8) Antistatic (9) Corrosion inhibition.

 Classification of Biosurfactants

Based on chemical structures biosurfactants may be classified as –

  1. Glycolipids – Trehalose lipids, Sophorolipids and Rhamnolipid
  2. Lipopeptides and Lipoproteins – Large number of cyclic lipopeptides including decapeptides antibiotics (Gramicidins) Lipopeptide antibiotics (Polymyxins) are produced. Bacillus subtilis produces most powerful biosurfactant lipopeptide Surfactin. It lowers surface tension from 79 to 27.9 mN/m at concentration of as low as 0.005%. Bacillus licheniformis also produces various biosurfactants.
  3. Fatty Acids – The fatty acids produced from alkanes by microbial oxidations act as surfactants. Microorganisms also produce complex fatty acids containing OH groups and alkyl branches e.g. corynomucolic acids.
  4. Phospholipids – These are major components of microbial membranes. When certain CxHy-degrading bacteria or yeast are grown on alkane substrates, the level of phospholipids increases greatly. Phospholipids from hexadecane-grown Acinetobacter sp. have potent surfactant properties.
  5. Neutral Lipids
  6. Polymeric Biosurfactants
  7. Particulate Biosurfactants – Extracellular membrane vesicles of Acinetobacter species strain HO1-N with diameter of 20 to 50 nm and buoyant density of 1.158g/cm3 are composed of protein, phospholipid and lipopolysaccharide.

Glycolipids and lipopeptides are low molecular weight biosurfactants that effectively lower surface and interfacial tensions. High molecular weight compounds include extracellular polysacch arides, lipopolysaccharides, proteins and lipoproteins that have high affinity for surface binding.

 

(I)            Glycolipids: Most known biosurfactants are glycolipids. They consist of mono-, di-, tri- and tetrasaccharides. They include Glucose, Galactose, Mannose, Rhamnose, Glucuronic acid. The fatty acid component has the same composition as that of phospholipid of same microorganism. Among glycolipids the best known are Sophorolipids, Trehalolipids and rhamnolipids.

(1)           Sophorolipids: These are produced by different strains of the yeast, Torulopsis. The sugar unit is the disaccharide sophorose which consists of two b -1,2-linked glucose units. The 6 and 6¢ hydroxy groups are generally acetylated. The sophorolipids reduce surface tensions between individual molecules at the surface, although they are effective emulsifying agents. The sophorolipids of Torulopsis have been reported to stimulate, inhibit, and have no effecton growth of yeast on water-insoluble substrates.

(2)           Trehalolipids: These are found in Mycobacterium species. Disaccharide Trehalose is linked with C-6 and C-6’ to mycolic acid. Mycolic acids are long chain alpha branched beta hydroxyl fatty acids. Trehalolipids differ from each other in size and structure of mycolic acid, number of carbon atoms and degree of unsaturation. Trehalolipids are also produced by Rhodococcus, Arthrobacter, Nocardia and Corynebacterium species.

(3)           Rhamnolipids: Rhamnolipid is produced as mixtures in various proportions, including one or two rhamnoses attached to b-hydroxyalkanoic acid. Rhamnolipid is composed of rhamnose sugar molecule and b-hydroxyalkanoic acid. The lengths of the fatty acid chains of rhamnolipid vary significantly, resulting in a multitude of different rhamnolipid congeners. This includes fatty acyl chains with lengths of 8, 10, 12, and 14 carbons, as well as of 12- or 14-carbon chains with a single doublebond. The type of rhamnolipid produced depends on the bacterial strain, the carbon source used, and the process strategy. Rhamnolipid induces a remarkably larger reduction in the surface tension of water from 72 to values below 30 mN/m and it reduces the interfacial tension of water/oil systems from 43 to values below 1 mN/m. Rhamnolipid also has an excellent emulsifying power with a variety of hydrocarbons and vegetable oils.

The rhamnosyltransferase 1 complex (RhlAB) is the key enzyme responsible for transferring the rhamnose moiety to the b-hydroxyalkanoic acid moiety to biosynthesize rhamnolipid. Rhamnolipid as a potent natural biosurfactant has a wide range of potential applications, including enhanced oil recovery (EOR), biodegradation, and bioremediation.

Some Pseudomonas sp. produce large quantities of a glycolipid consisting of two molecules of rhamnose and two molecules of b -hydroxydecanoic acid. While the OH group of one of the acids is involved in glycosidic linkage with the reducing end of the rhamnose disaccharide, the OH group of the second acids is involved in ester formation. Since one of the carboxylic acid is free, the rhamnolipids are anions above pH 4.0. Rhamnolipids are reported to lower surface tension, emulsify CxHy, and stimulate growth of Pseudomonas on n-hexadecane. Formation of rhamnolipids by Pseudomonas sp. MVB was greatly increased by nitrogen limitations. The pure rhamnolipid lowered the interfacial tension against n-hexadecane in water to about 1 mN/m and had a critical micellar concentration (cmc) of 10 to 30 mg/l depending on the pH and salt conditions.

(II)           Lipoproteins and Lipopeptides: Lipoprotein surfactin is produced by Bacillus species. Surfactin contains 7 amino acids bonded to hydroxyl groups of 14-carbon acid. Surfactin has ability to lyse mammalian erythrocytes and form spheroplasts. This hemolytic property is used to detect surfactin production. Surfactin is powerful biosurfactant and reduces surface tension from 72 to 27 mN per m-1 at as low as 0.001% concentration.

(III)          Fatty Acids: Fatty acids produced from alkanes are also considered as surfactants.They have OH group and alkyl branch. Example is Corynomucolic acid. The hydrophylic and lipophylic balance of fatty acids are clearly related to length of hydrocarbon chain. For lowering surface tension most active saturated fatty acids are in the range of C12-C14.

(IV)         Phospholipids: When certain hydrocarbon degrading microorganisms are grown on alkane substrates the level of phospholipids increases. They are part of membranes. Organisms like Thiobacillus thioxidans, Acinetobacter produce them.

(V)           Polymeric Biosurfactants: Examples are Liposan, Emulsan, biodispersan, alasan, mannoprotein and polysaccharide-protein complexes. Liposan is composed of 83% carbohydrate and 17% protein and is produced by Candida lipolytica. Mannoproteins are produced by Saccharomyces cerevisiae and contain 44% mannose and 17% protein.

 

 

 

 

 

 

 

Structures of various Biosurfactants:

surfactants

Advantages of Biosurfactants

  1. Biodegradable
  2. Non-toxic or low in toxicity during manufacture as well as during application
  3. More specific in action
  4. Raw materials used for their manufacture can be wastes too
  5. Greater foaming
  6. They work at more extreme temperatures and pH and salinity
  7. They are not animal-based
  8. They may be derived from renewable resources like soil, corn, sugar cane, sugar beets, vegetable or olive oil
  9. They are alternative to petroleum-derived synthetic surfactants.
  10. Biocompatability and digestibility, which allows their application in cosmetics, pharmaceuticals and as functional food additives.
  11. Acceptable production economics. They can be produced from industrial wastes.
  12. Wide chemical diversity so wide applications.
  13. Biosurfactants may act as de-emulsifiers (destabilize emulsions) or as emulsifiers (stabilize emulsions). High molecular-mass biosurfactants are in general better emulsifiers than low-molecular-mass biosurfactants.

 

Disadvantages of Biosurfactants

  1. Problems related to large scale and cheap production of biosurfactants
  2. To obtain pure substances particularly for pharmaceutical, food and cosmetic applications
  3. Overproducing strains of microorganisms are rare, so low productivity is obtained and complex media have to be used.
  4. Large scale production of biosurfactants is expensive unless wastes are used as raw materials.
  5. Regulation of biosurfactant synthesis is hardly understood. So improvements in production yields are difficult.
  6. Improvement in production yield is also hampered by foam formation. Immobilized systems provide productivity of 3glit-1hr-1.
  7. Downstream processing requires multiple steps.

 

Microbial Surfactants

The type and amount of the microbial surfactants produced depend primarily on the producer organism, factors like carbon and nitrogen, trace elements, temperature, and aeration.

Biosurfactant research, particularly related to production enhancement and economics, has been confined mostly to a few genera of microorganisms such as Bacillus, Pseudomonas and Candida.

3 bacterial strains were found as potential biosurfactant producers and identified as Bacillus megaterium, Corynebacterium kutscheri and Pseudomonas aeruginosa. Preliminary characterization of biosurfactant products for isolated B. megaterium, C. kutscheri and P. aeruginosa were glycolipid, glycolipopetide and lipopeptide respectively.

 

Screening for biosurfactant production:

Following tests are performed while screening the microorganisms for biosurfactant production.

1. Microorganism and Hemolytic activity

2. Bacterial adhesion to hydrocarbons (BATH)

3. Visualization of bacteria in oil droplets

4. Drop-collapse test

5. Emulsification assay

 

Why they are produced by microorganisms?

Biosurfactant production can be induced by hydrocarbons or other water-insoluble substrates. When grown on hydrocarbon substrate as the carbon source, these microorganisms synthesize a wide range of chemicals with surface activity, such as glycolipid, phospholipid and others. These chemicals are apparently synthesized to emulsify the hydrocarbon substrate and facilitate its transport into the cells.

In some bacterial species like Pseudomonas aerugenosa, biosurfactants are also involved in a group motility behavior called as swarming motility.

 

Various Biosurfactants Produced from Different Microbes

No. Microbe Type of surfactant
1 Torulopsis bombicola Glycolipid (sophorose lipid)
2 Pseudornonas aeruginosa Glycolipid (rhamnose lipid)
3 Bacillus licheniformis Lipoprotein (surfactin)
4 Bacillus subtilis Lipoprotein (sufactin)
5 Pseudornonas sp. DSbl 2874 Glycolipids ( rhamnose lipid)
6 Arthrobacter paraffineus Sucrose and fructose Glycolipid
7 Arthrobacter Glycolipid
8 Pseudornonas fluorescens Rhamnose lipid
9 Pseudornonas sp. blGB Rhamnose lipid
10 Torulopsis petrophilurn Glycolipid and/or protein
11 Candida tropicalis Polysaccharide-fatty acid complex
12 Rhodococcussp Trehalose lipids
13 Torulopsis sp Sophorolipids
14 Arthrobacter calcoaceticus Lipopolysaccharide
15 Candida lipolytica Liposan
16 Candida bombicola (formerly Torulopsis) Sophorolipids

Liposan is extracellular water-soluble emulsifier produced by Candida lipolytica. It is composed of 83% carbohydrate and 17% protein. The carbohydrate portion is composed of heteropolysaccharide consisting of glucose, galactose, galactosamine, galacturonic acid Liposan does not reduce surface tension, but has been used successfully to emulsify edible oils so acts as emulsifier.

 

Biosurfactants Production

Microbial biosurfactants are not competitive to chemical surfactants due to high production cost and low yields. So commercialization of biosurfactants is still less. Production technology for biosurfactants has improved productivity by 10-20 fold but still needs further significant improvements.

Yields of the biosurfactants were maximum at the time when lowest surface tension values were recorded in bacterial cultures. Thus reduction of surface tension of the medium is a rapid method for assay of maximum biosurfactant formation prior to their actual isolation.

Biosurfactant Manufacturers

 

  1. Kao Co Ltd : Sophorolipids
  2. Iwata Chemical Co Ltd : spiculosporic acid and Rhamnolipids
  3. Wako Pure Chem. Industries : Surfactin
  4. MG Intobio Co., Ltd. South Korea – produce microbial surfactants including sophorolipids for soaps with new functions. Sopholine is brand name of functional soaps with sophorolipids which synthesized and secreted by some yeasts. Used in skin care products, body cleansers.
  5. Jeneil Biosurfactant Company (USA) won the Small Business Award for its rhamnolipid biosurfactant, a natural, biodegradable, low toxicity alternative to synthetic surfactants that provides good emulsification, wetting, detergency, and foaming properties. Rhamnolipids produced by this company are marketed as EPA-approved biofungicide by a trade name ZONIX Biofungicide. Also its RECO product line is used to clean and recover oils from storage tanks. Various grades of Rhamnolipids are used for variety of formulations.
  6. Groupe Soliance is the company in France which manufactures sophorolipids under the trade name Sopholiance which is used in cosmetic and skin products having antimicrobial activity especially against Corynebacterium xerosis and Propionibacterium acnes.
  7. Ecover is the company from Belgium which produces Sophorolipids to be used for household and industrial cleaning products.
  8. AGAE Technologies LLC AGAE Technologies LLC, (http://www.agaetech.com) a new Corvallis biotechnology company started functioning in 2011. AGAE specializes in the innovative research, manufacturing and marketing of biosurfactants. Its technology is based on licensed intellectual property patented by Oregon State University.

The company licensed the patented technology from Oregon State University (OSU) and has conducted its own research on cost-effective, high-yield processes for manufacturing a compound known as a rhamnolipid biosurfactant.

Synthesized by the newly discovered NY3 strain of the Pseudomonas aeruginosa, AGAE Technologies’ rhamnolipid biosurfactants “are nontoxic, environmentally benign and completely biodegradable.

The increasing use of biosurfactants is being driven by technology breakthroughs, environmental awareness and tightening of regulations regarding chemical surfactants.

There are customer inquiries from North America and Europe. They are developing commercial-grade products of various purity specifications for pharmaceuticals, environmental bioremediation, personal care and several other application segments.

Rhamnolipids were discovered about 60 years ago. Rhamnolipids contain L-rhamnose and β-hydroxyl fatty acids, with amphiphilic properties (both hydrophilic and hydrophobic). AGAE Technologies is now producing a product known as R-95 (HPLC/MS-grade) rhamnolipids, allowing the company to become the only known supplier of pure rhamnolipid compounds to the world market.

Company has applied the latest genome sequencing technologies to strain improvement for NY3 and creating a nonpathogenic, high-yield rhamnolipid producer. Using renewable low-cost sources of ingredients, increasing the yields, and reducing costs by scaling up production, company wants to promote the global applications of these very eco-friendly biosurfactant molecules.

The industry expanse is quite broad, from pharmaceutical and cosmetics-grade customers to biopesticide, soil enhancement, bioremediation and oil spill/tank cleaning companies.

  1. There are also several types of biosurfactants being commercially produced by companies such as Kaneka, Toyobo and Saraya in Japan.

 

Inexpensive Raw Materials for Production of Biosurfactants

  1. Starchy substrates
  2. Vegetable oils and Oil wastes
  3. Olive oil mill effluent
  4. Whey
  5. Distillery wastes
  6. Animal fats
  7. Soapstocks
  8. Molasses

The residues from tropical agronomic crops such as cassava (peels), soybean (hull), sugar beet, sweet potato (peel and stalks), potato (peel and stalks), sweet sorghum, rice and wheat bran and straw); hull soy, corn and rice; bagasse of sugarcane and cassava; residues from the coffee processing industry such as coffee pulp, coffee husks, spent coffee grounds; residues of the fruit processing industries such as pomace and grape, waste from pineapple and carrot processing, banana waste; waste from oil processing mills such as coconut cake, soybean cake, peanut cake, canola meal and palm oil mill waste; saw dust, corn cobs, carob pods, tea waste, chicory roots etc. have been reported as substrates for biosurfactant production.

 

Extraction Processes for Biosurfactants

No. Process Biosurfactant recovered by the method
1 Adsorption Glycolipids, Lipopeptides, Rhamnolipids
2 Centrifugation Glycolipids
3 Crystalization Cellobiolipids, Glycolipids
4 Diafiltration and precipitation Glycolipids
5 Foam fractionation Surfactin
6 Precipitation by acid Surfactin
7 Precipitation by acetone Bioemulsifiers, Glycolipids
8 Precipitation by ammonium acetate Bioemulsifiers, Emulsan
9 Solvent Extraction Sophorolipids, Trehalose lipids
10 Ultrafiltration Glycolipids, Surfactin

 

Estimation of Biosurfactant activity

This involves measuring the changes in surface and interfacial tensions, stabilization and destabilization of emulsions and hydrophilic lipophylic balance (HLB). Using tensiometer the surface tension and air/water and oil/water interfaces can be easily determined. The surface tension of distilled water is noted to be 72mN m-1 and addition of biosurfactant lowers it to as low as 28mN m-1. Thus adding biosurfactant to water reduces its surface tension to critical level above which amphiphilic molecules readily form supramolecular structures like micells, bilayers, and vesicles known as Critical Micelle Concentration (CMC). CMC therefore is defined as ability of biosurfactant within aqueous phase and is usually used to measure efficiency of biosurfactant.

Analytical methods like HPLC, TLC, FTIR, HPLC-MS, GC-MS are used for qualitative and quantitative estimation of biosurfactants.

Economics of Biosurfactant Production

Economical large scale production of biosurfactants is still a challenge. The biosurfactant surfactin (98% purity) available from Sigma Chemical Company costs approximately $153 for a 10 mg vial. The cost of the RAG-1 emulsan containing broth was 50 dollar/kg and would therefore cost much more to extract, concentrate or purify the product. Further for higher potency product the cost will increase further. As compared to that cost of chemical surfactant is just $1 per pound (lb). However, environmental benefits of biosurfactants are their plus point and considering that, 3-5 dollars per lb for biosurfactant may be interesting and competitive.

Key factors affecting the efficiency of biosurfactant production in terms of higher yields and lower production costs are –   (i) cost of substrates (ii) mixture of products and therefore cost of purification (iii) problems in upscaling (iv) higher cost of downstream processing due to use of antifoam agents.

The main strategy to achieve this are through (i) assessment of the substrate and product output with focus on appropriate organism, nutritional balance and the use of cheap or waste substrates to lower the initial raw material costs involved in the process; (ii) development of efficient bioprocesses, including optimization of the culture conditions and cost-effective separation processes to maximize recovery; and (iii) development and use of overproducing mutant or recombinant strains for enhanced yields.

The use of the alternative substrates such as agro based industrial wastes is one of the attractive strategies for economical biosurfactants production. The development of low-cost processes and raw material can account for 10-30% of the final product cost. Further optimization of culture medium and growth conditions can significantly increase the yield.

Recently, reported the production of a new glycolipid biosurfactant from marine Nocardiopsis lucentensis MSA04 in solid-state cultivation. More studies are needed on these processes for efficient production of biosurfactants. The availability of processes with limited downstream processing will give significant economical advantages and have been sought after.

Applications –

They can be used as emulsifiers, de-emulsifiers, wetting agents, spreading agents, foaming agents, functional food ingredients and detergents in various industrial sectors such as: Petroleum and Petrochemicals, Organic Chemicals, Foods and Beverages, Cosmetics and Pharmaceuticals, Mining and Metallurgy, Agrochemicals and Fertilizers, Environmental Control and Management, and many others.

Biosurfactants provide high value surface properties, biodegradability, and environmental compatibility that synthetic detergents lack. Production costs must be lowered and high yield mutant strains need to be developed.

 

No. Industry Application Role of biosurfactants
1 Petroleum Enhanced oil recovery Improving oil drainage into well bore, stimulating release of oil entrapped by capillaries, wetting of solid surfaces, reduction of oil viscosity and oil pour point, lowering of interfacial tension, dissolving of oil
De-emulsification De-emulsification of oil emulsions, oil solubilization, viscosity reduction, wetting agent
2 Environmental Bioremediation Emulsification of hydrocarbons, lowering of interfacial tension, metal sequestration
3 Soil remediation & flushing Emulsification through adherence to hydrocarbons, dispersion, foaming agent, detergent, soil flushing
4 Food Emulsification and de-emulsification Emulsifier, solubilizer, demulsifier, suspension, wetting, foaming, defoaming, thickener, lubricating agent
5 Functional ingredient Interaction with lipids, proteins and carbohydrates, protecting agent
6 Biological Microbiological Physiological behaviour such as cell mobility, cell communication, nutrient accession, cell–cell competition, plant and animal pathogenesis
7 Pharmaceutical Pharmaceuticals and therapeutics Antibacterial, antifungal, antiviral agents, adhesive agents, immunomodulatory molecules, vaccines, gene therapy
8 Agricultural Biocontrol Facilitation of biocontrol mechanisms of microbes such as parasitism, antibiosis, competition, induced systemic resistance and hypovirulence
9 Bioprocessing Downstream processing Biocatalysis in aqueous two-phase systems and microemulsions, biotransformations, recovery of intracellular products, enhanced production of extracellular enzymes and fermentation products
10 Cosmetic Health and beauty products Emulsifiers, foaming agents, solubilizers, wetting agents, cleansers, antimicrobial agents, mediators of enzyme action

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>