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Trends in Food Science & Technology 18 (2007) 252e259

Biosurfactants in

food industry

M. Nitschkea,*

and S.G.V.A.O. Costab

aDepartment of Microbiology,

EMBRAPA Food Technology, Av. das Americas,

29501, Rio de Janeiro, RJ CEP 23020-470, Brazil

(Tel.: D55 21 24109590; fax: D55 21 24101090;

e-mail: [email protected])bDepartment of Biochemistry and Microbiology,

Institute of Biological Sciences,UNESP/Rio Claro, Av. 24-A, 1515,

CEP 13506-900, C.Postal 199,

Rio Claro- SP, Brazil

The increasing environmental concern about chemical surfac-

tants triggers attention to microbial-derived surface-active

compounds essentially due to their low toxicity and biode-

gradable nature. At present, biosurfactants are predominantly

used in remediation of pollutants; however, they show poten-

tial applications in many sectors of food industry. Associated

with emulsion forming and stabilization, antiadhesive and an-

timicrobial activities are some properties of biosurfactants,

which could be explored in food processing and formulation.

Potential applications of microbial surfactants in food area and

the use of agroindustrial wastes as alternative substrates for

their production are discussed.

IntroductionSurfactants are amphiphilic compounds containing both

hydrophobic (nonpolar) and hydrophilic (polar) moietiesthat confer ability to accumulate between fluid phasessuch as oil/water or air/water, reducing the surface and in-terfacial tensions and forming emulsions (Desai & Banat,1997). The surface activity properties make surfactantsone of the most important and versatile class of chemicalproducts, used on a variety of applications in household,industry and agriculture (Deleu & Paquot, 2004).

* Corresponding author.

0924-2244/$ - see front matter � 2007 Elsevier Ltd. All rights reserved.doi:10.1016/j.tifs.2007.01.002

Review

Biosurfactants (bioemulsifiers) are a structurally diversegroup of surface-active molecules synthesized by microor-ganisms. Rhamnolipids from Pseudomonas aeruginosa,surfactin from Bacillus subtilis, emulsan from Acineto-bacter calcoaceticus and sophorolipids from Candidabombicola are some examples of microbial-derived surfac-tants. Originally, biosurfactants attracted attention as hydro-carbons dissolution agents, but the interest in thesemolecules have been increasing considerably in the pastfive decades as alternative to chemical surfactants (carboxy-lates, sulphonates and sulphate acid esters) specially infood, pharmaceutical and oil industry (Banat, Makkar, &Cameotra, 2000; Desai & Banat, 1997). The main reasonsfor the spreading interest in biosurfactants are their environ-mental friendly nature, since they are easily biodegradable(Mohan, Nakhla, & Yanful, 2006) and have low toxicity(Flasz, Rocha, Mosquera, & Sajo, 1998), and their uniquestructures which provide new properties that classicalsurfactants may lack.

Most work on biosurfactants applications has beenfocusing on bioremediation of pollutants (Mulligan, 2005);however, these microbial compounds exhibit a variety ofuseful properties for the food industry specially as emulsi-fiers, foaming, wetting, solubilizers (Banat et al., 2000),antiadhesive and antimicrobial agents (Singh & Cameotra,2004). Moreover, an increasing consciousness among con-sumers demands for reducing the use of artificial or chem-ically synthesized compounds by replacing it for morenatural food ingredients and additives (Shepherd, Rockey,Sutherland, & Roller, 1995). Despite the advantagesdemonstrated by biosurfactants, few reports are availableregarding their use on food products and food processing.

This paper discusses the properties and applications ofmicrobial surfactants which can be of interest for foodand food-related industries, providing also an overview ofthe emerging fields for their employment and consideringthe exploitation of agroindustrial wastes as alternativesubstrates for biosurfactant production.

Classification of biosurfactantsMicrobial surfactants are categorized by their chemical

composition and microbial origin. Rosenberg and Ron(1999) suggested that biosurfactants can be divided intolow-molecular-mass molecules, which efficiently lowersurface and interfacial tension, and high-molecular-masspolymers, which are more effective as emulsion stabilizing

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253M. Nitschke, S.G.V.A.O. Costa / Trends in Food Science & Technology 18 (2007) 252e259

agents. The major classes of low-mass surfactants includeglycolipids, lipopeptides and phospholipids, whereas highmass includes polymeric and particulate surfactants.

Most biosurfactants are either anionic or neutral and thehydrophobic moiety is based on long-chain fatty acids orfatty acids derivatives whereas the hydrophilic portioncan be a carbohydrate, aminoacid, phosphate or cyclic pep-tide. Table 1 shows the major biosurfactant classes and themicroorganisms involved; note that bacteria are the pre-dominant group of surfactant-producing organisms how-ever some yeast species are also involved. Bodour et al.(2004) have recently described a new class of biosur-factants named flavolipids produced by a soil isolatedFlavobacterium sp. The new surfactant showed strongsurface activity and emulsifying ability, and exhibits a polarmoiety that features citric acid.

Properties of biosurfactantsThe main distinctive features of microbial surfactants

that can be of interest for food processing are related totheir surface activity; tolerance to pH, temperature andionic strength; biodegradability; low toxicity; emulsifyingand demulsifying ability and antimicrobial activity. Thesetopics are discussed below.

Surface and interface activityA good surfactant can lower surface tension (ST) of

water from 72 to 35 mN/m and the interfacial tension (IT)water/hexadecane from 40 to 1 mN/m (Mulligan, 2005).

Table 1. Major types of microbial surfactants

Surfactant class Microorganism

GlycolipidsRhamnolipids Pseudomonas aeruginosaTrehalose lipids Rhodococcus erithropolis,

Arthobacter sp.Sophorolipids Candida bombicola, Candida

apicolaMannosylerythritol lipids Candida antartica

LipopeptidesSurfactin/iturin/fengycin Bacillus subtilisViscosin Pseudomonas fluorescensLichenysin Bacillus licheniformisSerrawettin Serratia marcescens

Phospholipids Acinetobacter sp.,Corynebacterium lepus

Fatty acids/neutral lipidsCorynomicolic acids Corynebacterium insidibasseosum

Polymeric surfactantsEmulsan Acinetobacter calcoaceticusAlasan Acinetobacter radioresistensLiposan Candida lipolyticaLipomanan Candida tropicalis

Particulate biosurfactantsVesicles Acinetobacter calcoaceticusWhole microbial cells Cyanobacteria

Adapted from Deleu and Paquot, 2004; Desai and Banat, 1997;and Rosenberg and Ron, 1999.

Surfactin from B. subtilis can reduce ST of water to25 mN/m and IT water/hexadecane to <1 mN/m (Cooper,MacDonald, Duff, & Kosaric, 1981). The rhamnolipidsfrom P. aeruginosa decreased ST of water to 26 mN/mand IT water/hexadecane to value <1 mN/m (Syldatk,Lang, & Wagner, 1985) however, some rhamnolipid homo-logues have demonstrated lower values (Nitschke, Costa, &Contiero, 2005). The sophorolipids from C. bombicolawere reported to reduce ST to 33 mN/m and IT to 5 mN/m(Cooper & Paddock, 1984). In general, biosurfactants aremore effective and efficient and their CMC (critical micelleconcentration) is about 10e40 times lower than chemicalsurfactants, i.e., less surfactant is necessary to get a maximaldecrease on ST (Desai & Banat, 1997).

Temperature, pH and ionic strength toleranceMany biosurfactants and their surface activity are not af-

fected by environmental conditions such as temperature andpH. McInerney, Javaheri, and Nagle (1990) reported that li-chenysin from Bacillus licheniformis JF-2 was not affectedby temperature (up to 50 �C), pH (4.5e9.0) and by NaCland Ca concentrations up to 50 and 25 g/L, respectively.A lipopeptide from B. subtilis LB5a was stable after auto-clave (121 �C/20 min) and after 6 months at �18 �C; thesurface activity did not change from pH 5 to pH 11 andNaCl concentrations up to 20% (Nitschke & Pastore,2006). The Antarctic psychrophilic strain Arthrobacter pro-tophormiae produced a biosurfactant that was thermostable(30e100 �C) and pH (2e12) stable (Pruthi & Cameotra,1997). Industrial processes frequently involve exposure toextremes of temperature, pressure, pH and ionic strength,hence there is a continuous need to isolate new microbe-derived products able to function under these conditions(Cameotra & Makkar, 1998). The production of surfactantsfrom extremophiles microorganisms, has gained attentionin last years once the unique properties of these compoundsare of considered commercial interest.

BiodegradabilityUnlike synthetic surfactants, microbial-produced com-

pounds are easily degraded (Mohan et al., 2006) and partic-ularly suited for environmental applications such asbioremediation (Deleu & Paquot, 2004; Mulligan, 2005).The increasing environmental concern among consumersand the regulatory rules imposed by governments forcingindustry to search for alternative products such as biosur-factants (Cameotra & Makkar, 1998).

Low toxicityAlthough few data are available in literature regarding

the toxicity of microbial surfactants, they are generally con-sidered low or non-toxic products and therefore, appropri-ate for pharmaceutical, cosmetic and food uses. Poremba,Gunkel, Lang, and Wagner (1991a) reported that a syntheticanionic surfactant (Corexit) displayed a LC50 (concentra-tion lethal to 50% of test species) against Photobacterium

254 M. Nitschke, S.G.V.A.O. Costa / Trends in Food Science & Technology 18 (2007) 252e259

phosphoreum 10 times lower than rhamnolipids, demon-strating the higher toxicity of the chemical-derived surfac-tant. When comparing the toxicity of six biosurfactants,four synthetic surfactants and two commercial dispersants,Poremba, Gunkel, Lang, and Wagner (1991b) found thatmost biosurfactants were degraded faster, except for a syn-thetic sucrose-stearate that showed structure homology toglycolipids and was degraded more rapidly than the bio-genic glycolipids (rhamnolipids, trehalose lipids, sophoroselipids). These authors also reported that biosurfactantsshowed higher EC50 (effective concentration to decrease50% of test population) values than synthetic dispersants.

A biosurfactant from P. aeruginosa was compared witha synthetic surfactant (Marlon A-350) widely used in indus-try in terms of toxicity and mutagenic properties. Both as-says indicated the higher toxicity and mutagenic effect ofthe chemical-derived surfactant whereas biosurfactant wasconsidered slightly to non-toxic and non-mutagenic (Flaszet al., 1998). The comparison of acute and chronic toxicityof three synthetic surfactants (Corexit, 9500, Triton X-100,PSE-61) and three microbiological derived surfactants(rhamnolipid, emulsan, biological cleanser PES-51) com-monly used in oil spill remediation revealed that PES-61(synthetic surfactant) and Emulsan (biosurfactant) werethe least toxic whereas Triton X-100 (synthetic) was themost toxic (Edwards, Lepo, & Lewis, 2003).

Rhamnolipid surfactants are presently produced atcommercial scale by Jeneil Biosurfactant Corp. (www.biosurfactant.com) which offers diverse formulations fordifferent purposes. Recently, they developed a biofungicideformulation to prevent plant pathogenic fungi that wasconsidered of low acute mammalian toxicity and non-mutagenic and was approved by FDA for use in fruit,vegetables and legume crops. Additionally, the greater con-sumer awareness of adverse allergic effects caused by arti-ficial products stimulates the development of alternativeingredients, thus opening an excellent opportunity toexpand the use of natural surfactants of microbial origin(Cameotra & Makkar, 1998).

Emulsion forming and emulsion breakingAn emulsion is a heterogeneous system, consisting of at

least one immiscible liquid intimately dispersed in anotherin the form of droplets, whose diameter in general exceeds0.1 mm. Emulsions have an internal or dispersed and an ex-ternal or continuous phase, so there are generally two types:oil-in-water (o/w) or water-in-oil (w/o) emulsions. Suchsystems possess a minimal stability, which may be accentu-ated by additives such as surface-active agents (surfac-tants). Thus, stable emulsions can be produced with a lifespan of months and years (Velikonja & Kosaric, 1993).Biosurfactants may stabilize (emulsifiers) or destabilize(de-emulsifiers) the emulsion. High-molecular-mass biosur-factants are in general better emulsifiers than low-molecular-mass biosurfactants. Sophorolipids from Torulopsis bombicolahave been shown to reduce surface and interfacial tension

but not to be good emulsifiers (Cooper & Paddock,1984). By contrast, liposan has been shown not to reducesurface tension but used successfully to emulsify edibleoils (Cirigliano & Carman, 1985). Polymeric surfactantsoffer additional advantages because they coat the dropletsof oil, thereby forming very stable emulsions that nevercoalesce. This property is especially useful for making oil/water emulsions for cosmetics and food. In dairy products(soft cheese and ice creams) the addition of emulsifiers im-proves the texture and creaminess. This quality is of specialvalue for low-fat products (Rosenberg & Ron, 1999).

Evaluation of emulsifying ability of biosurfactants is ingeneral related to hydrocarbons such as kerosene becauseof their potential in environmental applications. Few at-tempts have been made to evaluate emulsion formingby biosurfactants with oils and fats used in food industry.A lipopeptide obtained from B. subtilis was able to formstable emulsions with soybean oil and coconut fat, suggest-ing its potential as emulsifying agent in foods (Nitschke &Pastore, 2006).

A manoprotein from Kluyveromyces marxianus was ableto form emulsions with corn oil that were stable for 3months; the yeast was cultivated on whey-based mediumsuggesting potential application as food bioemulsifier(Lukondeh, Ashbolh, & Rogers, 2003). The extracellularcarbohydrate-rich compound from Candida utilis wassuccessfully used as emulsifying agent in salad dressingformulations (Shepherd et al., 1995). The use of yeast forproduction of biosurfactant is interesting because these or-ganisms are generally recognized as safe (GRAS) and theyare already present in many food manufacturing processes,on the contrary, products derived from bacteria such as theopportunistic P. aeruginosa, still face some resistance con-cerning their use as food ingredients.

In some case, the emulsion, which is generated in onepart of the process, may have to be destabilized in a sub-sequent operation to develop a certain functional propertyto the final product. De-emulsification can be of interestin food processing specially when related to fat and oilproducts as well as in waste treatment (Kachholz &Schlingmann, 1987).

Antimicrobial activitySeveral biosurfactants have shown antimicrobial action

against bacteria, fungi, algae and viruses. The lipopeptideiturin from B. subtilis showed potent antifungal activity(Besson, Peypoux, Michel, & Delcambe, 1976). A signifi-cative reduction on the mycoflora present in stored grainsof corn, peanuts and cottonseeds was observed at iturinconcentration of 50e100 ppm (Klich, Arthur, Lax, &Bland, 1994). Inactivation of enveloped virus such asherpes and retrovirus was observed with 80 mM of sur-factin (Vollenbroich, Ozel, Vater, Kamp, & Pauli, 1997).Rhamnolipids inhibited the growth of harmful bloomalgae species Heterosigma akashivo and Protocentrumdentatum at concentration ranging from 0.4 to 10.0 mg/L

http://www.biosurfactant.com

http://www.biosurfactant.com


(Wang et al., 2005). A rhamnolipid mixture obtained fromP. aeruginosa AT10 showed inhibitory activity against thebacteria Escherichia coli, Micrococcus luteus, Alcaligenesfaecalis (32 mg/mL), Serratia marcescens, Mycobacteriumphlei (16 mg/mL) and Staphylococcus epidermidis (8 mg/mL); excellent antifungal properties against Aspergillusniger (16 mg/mL), Chaetonium globosum, Penicilliumcrysogenum, Aureobasidium pullulans (32 mg/mL) and thephytopathogenic Botrytis cinerea and Rhizoctonia solani(18 mg/mL) (Abalos et al., 2001). Sophorolipids and rham-nolipids were found to be effective antifungal agentsagainst plant and seed pathogenic fungi. Mycelial growthof Phytophthora sp. and Pythium sp. was 80% inhibitedby 200 mg/L of rhamnolipids and 500 mg/L of sophoro-lipids (Yoo, Lee, & Kim, 2005). The mannosylerythritollipid (MEL), a glycolipid surfactant from Candida antar-tica has demonstrated antimicrobial activity particularlyagainst Gram-positive bacteria (Kitamoto et al., 1993). Be-sides their antimicrobial activity new biological applica-tions of biosurfactants have been found and some reviewsconcerning the potential uses of microbial surfactants inbiomedical sciences were recently published (Rodrigues,Banat, Teixeira, & Oliveira, 2006; Singh & Cameotra,2004).

Potential food applicationsAlthough biosurfactants can be explored for several food

processing applications, in this section we emphasize theirpotential as food formulation ingredients and antiadhesiveagents.

Food formulation ingredientsApart from their obvious role as agents that decrease

surface and interfacial tension, thus promoting the forma-tion and stabilization of emulsions, surfactants can haveseveral other functions in food. For example to controlthe agglomeration of fat globules, stabilize aerated systems,improve texture and shelf-life of starch-containing prod-ucts, modify rheological properties of wheat dough andimprove consistency and texture of fat-based products(Kachholz & Schlingmann, 1987).

In bakery and ice cream formulations biosurfactants actcontrolling consistency, retarding staling and solubilizingflavor oils; they are also utilized as fat stabilizer and anti-spattering agent during cooking of oil and fats (Kosaric,2001). An improvement of dough stability, texture, volumeand conservation of bakery products was obtained by theaddition of rhamnolipid surfactants (Van Haesendonck &Vanzeveren, 2004). The authors also suggested the use ofrhamnolipids to improve properties of butter cream, crois-sants and frozen confectionery products. Recently, a bio-emulsifier isolated from a marine strain of Enterobactercloacae was described as a potential viscosity enhancementagent of interest in food industry especially due to the goodviscosity observed at acidic pH allowing its use in productscontaining citric or ascorbic acid (Iyer, Mody, & Jha, 2006).

L-Rhamnose has a considerable potential as precursorfor flavorings. It is already used industrially as precursorof high-quality flavor components like Furaneol (trademarkof Firmenich SA, Geneva). There is great interest in obtain-ing rhamnose lipids to provide a source of L-rhamnose,which already has an industrial application. L-Rhamnoseis obtained by hydrolyzing rhamnolipid surfactants pro-duced by P. aeruginosa (Linhardt, Bakhit, Daniels, Mayerl,& Pickenhagen, 1989).

Antiadhesive agentsA biofilm is described as a group of bacteria that have

colonized a surface. The biofilm not only includes the bac-teria, but it also describes all of the extracellular materialproduced at the surface and any material trapped withinthe resulting matrix (Hood & Zottola, 1995). The firststep on biofilm establishment is bacterial adherence whichis affected by factors including microorganism species,hydrophobicity of surface and electrical charges involved,environmental conditions and ability of microorganismsto produce extracellular polymers that help cells to anchorto surfaces (Zottola, 1994). Bacterial biofilms present infood industry surfaces are potential sources of contamina-tion, which may lead to food spoilage and disease transmis-sion (Hood & Zottola, 1995). Due to the fact that foodprocessors have a zero tolerance levels for pathogens likeSalmonella and also (in most countries) for Listeria mono-cytogenes, a single adherent cell may be as significant asa well developed biofilm; thus controlling the adherenceof microorganisms to food contact surfaces is an essentialstep in providing safe and quality products to consumers(Hood & Zottola, 1995).

The involvement of biosurfactants in microbial adhesionand detachment from surfaces has been investigated. A sur-factant released by Streptococcus thermophilus has beenused for fouling control of heat-exchanger plates in pasteur-izers as it retards the colonization of other thermophilicstrains of Streptococcus responsible for fouling (Busscher,van der Kuij-Booij, & van der Mei, 1996).

The bioconditioning of surfaces through the use of micro-bial surfactants have been suggested as a new strategy toreduce adhesion. Pre-treatment of silicone rubber withS. thermophilus surfactant inhibited by 85% the adhesion ofCandida albicans (Busscher, van Hoogmoed, Geertsema-Doornbusch, van der Kuij-Booij, & van der Mei, 1997)whereas surfactants from Lactobacillus fermentum and Lac-tobacillus acidophilus adsorbed on glass, reduced by 77%the number of adhering uropathogenic cells of Enterococcusfaecalis (Velraeds, van der Mei, Reid, & Busscher, 1996).Lately, the biosurfactant from L. fermentum was reportedto inhibit Staphylococcus aureus infection and adherenceto surgical implants (Gan, Kim, Reid, Cadieux, & Howard,2002). The use of biosurfactants released by Lactobacillistrains is very promising once these microorganisms are nat-urally present in human flora and have also a probiotic effect(Singh & Cameotra, 2004). Much more research is needed


however, to understand the contribution of lactobacilli sur-factants in preventing pathogen colonization, the biochemi-cal aspects of biosynthesis and their structural characterization.

Surfactin decreased the amount of biofilm formation bySalmonella typhimurium, Salmonella enterica, E. coli andProteus mirabilis in PVC plates and vinyl urethral catheters(Mireles, Toguchi, & Harshey, 2001). Irie, o’Toole, andYuk (2005) demonstrated the disruption of Bordetella bron-chiseptica biofilms by rhamnolipids and recently, it wasfound that silicone rubber conditioned with rhamnolipidsreduced the adhesion rates of Streptococcus salivarius andCandida tropicalis by 66%. The number of adhered cellsof S. aureus, S. epidermidis, S. salivarius and C. tropicaliswas reduced by 48% and the perfusion of biosurfactant toadhered cells produced a high detachment (96%) of micro-organisms (Rodrigues, Banat, van der Mei, Teixeira, &Oliveira, 2006).

The use of biosurfactants, which disrupts biofilms andreduce adhesion, in combination with antibiotics could rep-resent a novel antimicrobial strategy, once antibiotics are ingeneral less effective against biofilms than planktonic cells;the disruption of biofilm by biosurfactant can facilitate theantibiotic access to the cells (Irie et al., 2005).

The promising results of these works, with medical focus,suggest a potential application of biosurfactants for surfaceconditioning in food industry, since both the surfacematerials and microorganisms involved are of commoninterest.

An interesting work regarding the use of biosurfactantsto inhibit the adhesion of the pathogen L. monocytogenesin two types of surfaces classically used in food industryhas been conducted by the group of Meylheuc, van Oss,and Bellon-Fontaine (2001). The preconditioning of stain-less steel and PTFE surfaces with a biosurfactant obtainedfrom Pseudomonas fluorescens inhibits the adhesion ofL. monocytogenes L028 strain. A significant reduction(>90%) was attained in microbial adhesion levels in stain-less steel whereas no significant effect was observed inPTFE. Further work demonstrated that the prior adsorp-tion of P. fluorescens surfactant in stainless steel also fa-vored the bactericidal effect of disinfectants (Meylheuc,Renault, & Bellon-Fontaine, 2006). The ability of ad-sorbed biosurfactants obtained from Gram-negative(P. fluorescens) and Gram-positive (Lactobacillus helveti-cus) bacteria isolated from foodstuffs, in inhibiting the ad-hesion of L. monocytogenes to stainless steel was recentlyinvestigated. Adhesion tests showed that both biosurfac-tants were effective by decreasing strongly the level ofcontamination of the surface. The antiadhesive biologiccoating reduced either the total adhering flora and the vi-able/cultivable adherent L. monocytogenes on stainlesssteel surfaces (Meylheuc et al., 2006). Preliminary studiesregarding the corrosion effect of P. fluorescens surfactantin stainless steel suggested that it has also a good potentialas corrosion inhibitor (Dagbert, Meylheuc, & Bellon-Fontaine, 2006).

Considering the interesting properties demonstrated bybiosurfactants we can think on their future utilization asmultipurpose ingredients, which exhibit emulsifier, anti-adhesive, and antimicrobial activities simultaneously andthus, suitable for many food applications. Food processorshowever, does not yet use biosurfactants on a large scale asmany regulations regarding the approval of new food ingre-dients are required by governmental agencies, and this pro-cess could be quite long. Nevertheless, an increasingnumber of patents have been issued on biosurfactant (bio-emulsifier) claiming their use as additives for food, cos-metics and pharmaceutical products (Shete, Wadhawa,Banat, & Chopade, 2006), demonstrating the crescent inter-est in using these microbial-derived products.

Biosurfactant production from food andagroindustrial wastes

Another interesting approach for food industries, is totake advantage of their by-products or residues as substratesfor biosurfactant production. Currently, the main factor thatworks against the widespread use of biosurfactants is theeconomics of their production (Makkar & Cameotra, 2002).An important point that should be considered for develop-ment of cheaper processes is the selection of inexpensivemedium components which account for 10e30% of overallcosts (Cameotra & Makkar, 1998). To this end, good com-ponents seem to be agroindustrial by-products or wastes,once these residues generally contain high levels of carbo-hydrates or lipids to support growth and surfactant synthe-sis; moreover, the treatment and disposal costs for theseresidues are significant to industries which are invariablysearching for alternatives to reduce, reuse, recycle andvalorize their wastes.

The advantages of wastes materials are the huge sur-pluses and the possibility of production in regions withtemperate to tropical climates (Mercade & Manresa,1994). Thus, the research on alternative low-cost substratesis mainly centered on tropical agroindustrial crops and res-idues. Some attempts at using wastes for biosurfactant pro-duction and only a few types of surfactant produced fromwastes have been published. The main alternative sourcesfor biosurfactant production comprise oily residues, milkand distillery wastes, and carbohydrate-rich residues.

Oils and fatsMost oils and fats are used in the food industry, which

generates great quantities of wastes and so, their disposalis a growing problem. Candida antarctica and Candida api-cola synthesized surfactants (glycolipids) in a cultivationmedium supplemented with oil refinery waste, either withsoapstock (5e12% v/v) or post-refinery fatty acids (from2 to 5% v/v). The efficiency of glycolipids synthesis wasfrom 7.3 to 13.4 g/L and from 6.6 to 10.5 g/L in the me-dium supplemented with soapstock and post-refinery fattyacids, respectively (Bednarski, Adamczak, Tomasik, &Plaszczyk, 2004).


The meat processing industry is seeking new applica-tions for abundantly available, inexpensive animal’s fats.Sophorolipid production by C. bombicola was studied asa model of fat utilization for biosurfactant production. Ina pH controlled fermenter, 120 g/L of sophorolipid was ob-tained and the cells at the end of fermentation contained37% of protein and 14% lipids (Deshpande & Daniels,1995).

Frying oils is produced in large quantities for use bothin the food industry and at the domestic scale. Haba, Es-puny, Busquets, and Manresa (2000) studied a screeningprocess for the selection of microorganism’s strains ableto grow on frying oils (sunflower and olive) and accumu-late surface-active compounds in the culture media. P. aer-uginosa 47T2 was selected, showing a final production ofrhamnolipid of 2.7 g/L and a production yield of 0.34 grhamnolipid/g substrate. Sunflower oil soapstock was as-sayed as the carbon source for rhamnolipid productionby P. aeruginosa LBI strain, giving a final surfactantconcentration of 12 g/L in shaker and 16 g/L in bioreactorexperiments (Benincasa, Contiero, Manresa, & Moraes,2002). Equally Nitschke et al. (2005) evaluated edible oilsoapstocks as alternative low-cost substrates for the pro-duction of rhamnolipids by P. aeruginosa LBI strain.Wastes obtained from soybean, cottonseed, babassu, palmand corn oil refinery were tested. The soybean soapstockwaste was the best substrate, generating 11.7 g/L of rham-nolipids and a production yield of 75%. Vegetable oils andresidues from vegetable oil refinery are among the mostused low-cost substrates for rhamnolipids production(Nitschke et al., 2005).

Whey milk and distillery wastesThe disposal of cheese whey is a continuing and growing

problem to the dairy industry. A two-step batch cultivationprocess was developed to produce sophorolipids from wheyby C. bombicola and Cryptococcus curvatus. In the firststep, C. curvatus was grown on deproteinized whey concen-trates (DWC); the cultivation broth was disrupted witha glass bead mill and it served a medium for growth andsophorolipid production by C. bombicola (Daniel, Otto,Binder, Reuss, & Syldatk, 1999).

Dubey and Juwarkar (2001) reported biosurfactant pro-duction from synthetic medium and industrial wastes suchas distillery and whey by a sludge isolate P. aeruginosaBS2. The wastes were good substrates for growth and pro-liferation of bacteria and biosurfactant production in distill-ery and whey wastes reached maximal amounts of 0.9 and0.92 g/L, respectively, after 96 h of incubation.

Rodrigues, Moldes, Teixeira, and Oliveira (2006) per-formed a screening for Lactobacillus strains able to producesurfactants. The acid lactic bacteria Lactobacillus casei,Lactobacillus rhamnosus, Lactobacillus pentosus andLactobacillus coryniformis torquens were selected assurfactant-producing organisms with L. pentosus been

considered the most promising strain and whey as a poten-tial alternative substrate.

Carbohydrate-rich residuesFox and Bala (2000) demonstrated that potato process-

ing effluent was suitable alternative carbon source to gener-ate surfactant from B. subtilis ATCC 21332. B. subtilisexpresses an a-amylase which permits the utilization ofa starch-rich potato waste as substrate for biosurfactant pro-duction (Thompson, Fox, & Bala, 2000). Cassava waste-water is a carbohydrate-rich residue generated at largeamounts during the processing of cassava flour. This resi-due proved to be an appropriate substrate for biosurfactantbiosynthesis, providing not only bacterial growth and prod-uct accumulation but also a surfactant that has interestingand useful properties with potential for many industrialapplications (Nitschke & Pastore, 2003, 2004).

Molasses is a by-product of the sugar industry that is lowin price compared to other conventional sugar sources likesucrose or glucose and is rich in other nutrients such asminerals and vitamins (Makkar & Cameotra, 2002). TwoB. subtilis strains were able to produce lipopeptide surfac-tants using minimal medium supplemented with molassesas carbon source (Makkar & Cameotra, 1997). Molassesand corn steep liquor were used as the primary carbonand nitrogen sources for production of rhamnolipid biosur-factants by P. aeruginosa GS3; the interfacial tension ofculture medium against crude oil was reduced from 21 to0.47 mN/m (Patel & Desai, 1997).

Future trendsBiosurfactants show several properties which could be

useful in many fields of food industry; recently, their anti-adhesive activity has attracted attention as a new tool toinhibit and disrupt the biofilms formed in food contactsurfaces. The combination of particular characteristicssuch as emulsifying, antiadhesive and antimicrobial activi-ties presented by biosurfactants suggests potential applica-tion as multipurpose ingredients or additives.

Scant information regarding toxicity, combined withhigh production costs seems to be the major cause for thelimited uses of biosurfactants in food area. However, theuse of agroindustrial wastes can reduce the biosurfactantsproduction costs as well as the waste treatment expends,and also renders a new alternative for food and food-relatedindustries not only for valorizing their wastes but also tobecoming microbial surfactant producers. Biosurfactantsobtained from GRAS microorganisms like Lactobacilliand yeasts are of great promise for food and medicineapplications though, much more research is already requiredon this field. The prospect of new types of surface-activecompounds from microorganisms can contribute for the de-tection of different molecules in terms of structure and prop-erties, but the toxicological aspects of new and currentbiosurfactants should be emphasized in order to certify thesafe of these compounds for food utilization.


With the emphasis on the construction of a sustainablesociety in harmony with the environment, the introductionof green technology in all fields of industry is one of themost important challenges. Considering the social and tech-nological backgrounds, utilization of biosurfactants, whichare environmentally friendly and highly functional, havebecome more and more important.

AcknowledgementsWe thank Fundac~ao de Amparo a Pesquisa do Estado

de S~ao Paulo (FAPESP) for scholarship and Embrapa forproviding us the facilities for this work.

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