Bench-Scale Production of Biosurfactants and their Potential in Ex-Situ MEOR Application

The fermentative production of biosurfactants by five Bacillus strains in a bench-scale bioreactor and evaluation of biosurfactant-based enhanced oil recovery using sand pack columns were investigated. Adjusting the initial dissolved oxygen to 100% saturation, without any further control and with collection of foam and recycling of biomass, gave higher biosurfactant production. The microorganisms were able to produce biosurfactants, thus reducing the surface tension and interfacial tension to 28 mN/m and 5.8–0.5 mN/m, respectively, in less than 10 hours. The crude surfactant concentration of 0.08–1.1 g/L, and critical micelle concentration (CMC) values of 19.4–39 mg/L, corresponding to the biosurfactants produced by the different Bacillus strains, were observed. The efficiency of crude biosurfactant preparation obtained from Bacillus strains for enhanced oil recovery, by sand pack column studies, revealed it to vary from 30.22–34.19% of the water flood residual oil saturation. The results are indicative of the potential of the strains for the development of ex-situ, microbial-enhanced, oil recovery processes.     

Physicochemical and structural characterization of biosurfactant produced by <Emphasis Type="Italic">Pleurotus djamor</Emphasis> in solid-state fermentation

Biosurfactants are amphiphilic compounds produced by several microorganisms that reduce the surface tension. Low toxicity, optimal activity in extreme conditions, biodegradability and production from several wastes are main advantages of biosurfactants as compared to synthetic surfactants. Production of biosurfactant by a white rot fungus Pleurotus djamor on sunflower seed shell in solid-state fermentation was determined by emulsification indexes, oil spreading activity and surface tension (28.82 ± 0.3mN/m) measurement. The critical micelle concentration was detected as 0.964 ± 0.09 mg/mL. Also, the chemical and physicochemical properties of the biosurfactant produced were investigated. Considering the results of the chemical contents analysis, HPLC, FT-IR and ¹H-NMR, it can be concluded that the produced biosurfactant has a complex structure. Besides, resistance of its activity to environmental factors such as temperature, pH and salt concentration, as well as its thermal stability, were investigated. Additionally, the produced biosurfactant formed stabile emulsions with different hydrocarbons. Lastly, the performance of removing waste frying oil from contaminated sand of produced biosurfactant was detected as 76.57 ± 6%. Owing to its high emulsification capacity, low surface tension and critical micelle concentration, the biosurfactant, shows great potential for use in hydrocarbon removal applications.     

Application of Biosurfactants Produced by Pseudomonas aeruginosa SP4 for Bioremediation of Soils Contaminated by Pyrene

Biosurfactants are considered to facilitate PAHs dissolution in soil slurries for bioremediation applications. In this work, the carbon and nitrogen sources, pH, C/N ratio, and salinity, were considered for optimization of biosurfactant production by Pseudomonas aeruginosa SP4 isolate to enhance pyrene removal from the contaminated soil. Analysis of ANOVA indicated that the carbon source was the most effective factor, followed by pH, nitrogen source, C/N ratio, and salinity. Taguchi experimental design proposed the optimum operating conditions of olive oil, NH₄NO₃, C/N ratio of 5, salinity of 0.5%, and pH 7. Applying the conditions determined by Taguchi design led to a production yield of 452 mg L^?1 (13% improvement) at the optimum conditions. The main characteristics of produced biosurfactant included the critical micelle concentration (CMC) of 60 mg L^?1 and liquid medium surface tension of 29.5 mN m^?1. Produced biosurfactant was used for bioremediation of soil artificially contaminated with 500 mg kg^?1 of pyrene. Following the addition of 250 mg L^?1 biosurfactant, the pyrene removal of 84.6% was obtained compared to 59.8% for control sample without any surfactant.     

Characterization and properties of biosurfactants produced by a newly isolated strain <Emphasis Type="Italic">Bacillus methylotrophicus</Emphasis> DCS1 and their applications in enhancing solubility of hydrocarbon

Six biosurfactant-producing bacteria were isolated from hydrocarbon contaminated soils in Sfax, Tunisia. Isolates were screened for biosurfactant production by different conventional methods including hemolytic activity, surface tension reduction, drop-collapsing and oil displacement tests. All these screening tests show that all the isolates behave differently. Among the isolated bacteria, DCS1 strain was selected for further studies based on its highest activities and it was identified as Bacillus methylotrophicus DCS1. This strain was found to be a potent producer of biosurfactant when cultivated in mineral-salts medium supplemented with diesel oil (2 %, v/v) as a sole carbon source. Physicochemical properties and stability of biosurfactants synthesized by B. methylotrophicus DCS1 were investigated. The produced biosurfactants DCS1, from Landy medium, possess high surface activity that could lower the surface tension of water to a value of 31 from 72 mN m^?1 and have a critical micelle concentration (CMC) of 100 mg L^?1. Compared with SDS and Tween 80, biosurfactants showed excellent emulsification activities against different hydrocarbon substrates and high solubilization efficiency towards diesel oil. Biosurfactants DCS1 showed good stability in a wide range of temperature, pH and salinity. These results suggested that biosurfactants produced by B. methylotrophicus DCS1 could be an alternative to chemically synthesized surfactants for use in bioremediation processes to enhance the solubility of hydrophobic compounds.     

A Biosurfactant-Producing Pseudomonas aeruginosa Strain

A Pseudomonas aeruginosa strain producing an extracellular surfactant (biosurfactant) was isolated. The growth of this strain, referred to as 50.3, on a mineral glycerol-containing medium produces an emulsifying activity (60%) and decreases the surface tension of the culture liquid by a factor of 2.8 (to 25 mN/m). The optimum conditions for its growth and production of biosurfactants are intense aeration, pH 7.0–8.0, and the presence of Mg²⁺. The optimum biosurfactant properties were achieved when glucose was used as the only source of carbon and energy and NH₄Cl was used as a source of nitrogen. The biosurfactant was isolated from the culture liquid by extraction and precipitation.     

Production of water-soluble surface-active exolipids by Torulopsis apicola

Summary Several Torulopsis yeasts were screened for production of extracellular surface-active compounds. One strain, Torulopsis apicola IMET 43747, was studied in greater detail. Both on nalkanes and on carbohydrates it produced a mixture of water-soluble biosurfactants with remarkable interfacial activities and surface-tension values around 30 mN m^-1 and interfacial tension below 1 mN m^-1. Most of the biosurfactants are produced in the late exponential and in the early stationary growth phase. Production was increased by using hydrophobic compounds as the carbon source. The yields on n-alkanes were influenced by the concentrations of both the carbon source and the yeast extract. The effects of one purified biosurfactant on microbial growth on nalkanes and its antibacterial and antiphagal activities reveal new physiological aspects of biosurfactant generation by T. apicola.     

Production and characterization of a group of bioemulsifiers from the marine Bacillus velezensis strain H3

Marine microbes are a rich source of bioactive compounds, such as drugs, enzymes, and biosurfactants. To explore the bioactive compounds from our marine natural product library, an oil emulsification assay was applied to discover biosurfactants and bioemulsifiers. A spore-forming bacterial strain from sea mud was found to produce bioemulsifiers with good biosurfactant activity and a broad spectrum of antimicrobial properties. It was identified as Bacillus velezensis H3 using genomic and phenotypic data analysis. This strain was able to produce biosurfactants with an optimum emulsification activity at pH 6.0 and 2% NaCl by using starch as the carbon source and ammonium sulfate as the nitrogen source. The emulsification-guided isolation and purification procedure led to the discovery of the biosurfactant components, which were mainly composed of nC₁₄-surfactin and anteisoC₁₅-surfactin as determined by NMR and MS spectra. These compounds can reduce the surface tension of phosphate-buffered saline (PBS) from 71.8 to 24.8 mN/m. The critical micelle concentrations (CMCs) of C₁₄-surfactin and C₁₅-surfactin in 0.1 M PBS (pH 8.0) were determined to be 3.06?×?10^-5 and 2.03?×?10^-5?mol/L, respectively. The surface tension values at CMCs for C₁₄-surfactin and C₁₅-surfactin were 25.7 and 27.0 mM/m, respectively. In addition, the H3 biosurfactant exhibited antimicrobial activities against Staphyloccocus aureus, Mycobacterium, Klebsiella peneumoniae, Pseudomonas aeruginosa, and Candida albicans. Thus B. velezensis H3 is an alternative surfactin producer with potential application as an industrial strain for the lipopeptide production.     

Characterization and antimicrobial properties of lipopeptide biosurfactants produced by Bacillus subtilis SJ301 and Bacillus vallismortis JB201

Biosurfactant producing bacteria, terrestrial Bacillus subtilis SJ301 and marine Bacillus vallismortis JB201 were isolated from sites contaminated with crude oil and its by-products. Cellular growth and biosurfactant production of the isolates were studied with different carbon sources (glucose, fructose, glycerol and petrol). Both bacterial isolates synthesized biosurfactants in the presence of glucose at late log phase and in the presence of petrol at stationary phase at 35°C. Biosurfactants obtained from both bacteria reduced the surface tension of the growth medium below 33 mN/m and exhibited this capacity in cell-free filtrates also. Raising the temperature from 25 to 35°C, accelerated onset of biosurfactant production in both the isolates, however, change in pH values from 6.5 to 7.5 had no effect. Functional and structural characterization of the crude biosurfactants was carried out by FTIR and ¹H and ¹³C NMR spectroscopy and the compounds were identified as surfactin lipopeptides. Biosurfactant produced by the terrestrial B. subtilis SJ301 showed antimicrobial activity against Escherichia coli and Shigella dysenteriae whereas the marine B. vallismortis JB201 revealed antimicrobial activity against Klebsiella pneumoniae, Salmonella typhi and Streptococcus pneumoniae.     

Isolation and characterization of a biosurfactant‐producing Fusarium sp. BS‐8 from oil contaminated soil

This study reports characterization of a biosurfactant‐producing fungal isolate from oil contaminated soil of Missa Keswal oil field, Pakistan. It was identified as Fusarium sp. BS‐8 on the basis of macroscopic and microscopic morphology, and 18S rDNA gene sequence homology. The biosurfactant‐producing capability of the fungal isolates was screened using oil displacement activity, emulsification index assay, and surface tension (SFT) measurement. The optimization of operational parameters and culture conditions resulted in maximum biosurfactant production using 9% (v/v) inoculum at 30°C, pH 7.0, using sucrose and yeast extract, as carbon and nitrogen sources, respectively. A C:N ratio of 0.9:0.1 (w/w) was found to be optimum for growth and biosurfactant production. At optimal conditions, it attained lowest SFT (i.e., 32 mN m^?1) with a critical micelle concentration of ≥ 1.2 mg mL^?1. During 5 L shake flask fermentation experiments, the biosurfactant productivity was 1.21 g L^?1 pure biosurfactant having significant emulsifying index (E₂₄, 70%) and oil‐displacing activity (16 mm). Thin layer chromatography and Fourier transform infrared spectrometric analyses indicated a lipopeptide type of the biosurfactant. The Fusarium sp. BS‐8 has substantial potential of biosurfactant production, yet it needs to be fully characterized with possibility of relatively new class of biosurfactants. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:1065–1075, 2014     

Isolation and characterization of a biosurfactant from Deinococcus caeni PO5 using jackfruit seed powder as a substrate

Biosurfactant-producing bacteria were isolated from various sources in the south of Thailand. Isolates were screened for biosurfactant production using jackfruit seed powder (JSP) as a novel and promising substrate. The highest biosurfactant activity was obtained with a bacterial strain which was identified by 16S rRNA gene sequence analysis as Deinococcus caeni PO5. D. caeni PO5 was able to grow and reduce the surface tension of the culture supernatant from 67.0 to 25.0 mN/m after 87 h of cultivation when 40 g/l of JSP and 1 g/l of commercial monosodium glutamate were used as carbon and nitrogen sources, respectively. The biosurfactant obtained by ethyl acetate extraction showed high surface tension reduction (47.0 mN/m), a small critical micelle concentration value (8 mg/l), thermal and pH stability with respect to surface tension reduction and emulsification activity, and a high level of salt tolerance. Chemical characterization by biochemical testing, Fourier transform infrared spectroscopy, and mass spectra revealed that the obtained biosurfactant was a glycolipid-type biosurfactant. The obtained biosurfactant was capable of forming stable emulsions with various hydrocarbons and had the ability to enhance oil recovery, the solubility of polyaromatic hydrocarbons, heavy metal removal, and antimicrobial activity.     

Production and characterization of biosurfactant from marine bacterium Inquilinus limosus KB3 grown on low-cost raw materials

Inquilinus limosus strain KB3, isolated from marine sediment in the south of Thailand, was used to produce a biosurfactant from a mineral salts medium (MSM) with palm oil decanter cake (PODC) as a carbon source. It was found that cellular growth and biosurfactant production in MSM were greatly affected by the medium components. I. limosus KB3 was able to grow and to produce surfactant reducing the surface tension of medium to 28.2 mN/m and giving a crude surfactant concentration of 5.13 g/l after 54 h. The biosurfactant obtained was found to reduce the surface tension of pure water to 25.5 mN/m with the critical micelle concentration of 9 mg/l, and retained its properties during exposure to elevated temperatures (121 °C), high salinity (12 % NaCl), and a wide range of pH values. Chemical characterization by FT-IR, NMR, and ESI-MS revealed that the biosurfactant has a lipopeptide composition with molecular mass (m/z) of 1,032. The biosurfactant was capable of forming stable emulsions with various hydrocarbons and had the ability to enhance oil recovery, PAHs solubility, and antimicrobial activity.     

Enhancement of solubilization and biodegradation of petroleum by biosurfactant from Rhodococcus erythropolis HX-2

Abstract

The demand to repair areas contaminated with hydrocarbon products has led to the development of new technologies for the treatment of contaminants in an unconventional method, that is, no physical or chemical methods are used. Biosurfactants are amphiphilic biomolecules produced by microorganisms that can be used in environments contaminated by petroleum products due to their unexceptionable tensile properties. Petroleum degrading strain Rhodococcus erythropolis HX-2 was found to be an effective producer of biosurfactants. The resulting biosurfactant (named NK) exhibits high physicochemical properties in terms of surface activity. It is capable of reducing surface tension from 54.99 to 28.89?mN/m and critical micelle concentration (CMC) is 100?mg/L. NK was found to be a substitute for chemically synthesized surfactants because of its higher solubilization efficiency for petroleum and polycyclic aromatic hydrocarbons, superior to SDS, Tween 80, Triton X-100 and Rhamnolipid (a wide used biosurfactant). In addition, it exhibits favorable emulsion stability over a wide range of pH (3–10), temperature (20–100?°C) and salinity ranges (5–20?g/L). It was found that the addition of biosurfactant can improve the efficiency of petroleum degradation, therefore it has potential applications in bioremediation.

• Highlights

• Rhodococcus erythropolis HX-2 is an effective petroleum degrading strain.

• HX-2 is a potential source of biosurfactant production.

• The biosurfactant NK reduces surface tension and exhibits high emulsification activity.

• The biosurfactant NK is effective over a wide range of temperatures, pH and salinity.

• The biosurfactant NK shows high solubilization efficiency for petroleum as well as polycyclic aromatic hydrocarbons.

     

The Potential of Bacterial Isolates for Emulsification with a Range of Hydrocarbons

A study was undertaken to investigate the distribution of biosurfactant producing and crude oil degrading bacteria in the oil contaminated environment. This research revealed that hydrocarbon contaminated sites are the potent sources for oil degraders. Among 32 oil degrading bacteria isolated from ten different oil contaminated sites of gasoline and diesel fuel stations, 80% exhibited biosurfactant production. The quantity and emulsification activity of the biosurfactants varied. Pseudomonas sp. DS10‐129 produced a maximum of 7.5 ± 0.4 g/l of biosurfactant with a corresponding reduction in surface tension from 68 mN/m to 29.4 ± 0.7 mN/m at 84 h incubation. The isolates Micrococcus sp. GS2‐22, Bacillus sp. DS6‐86, Corynebacterium sp. GS5‐66, Flavobacterium sp. DS5‐73, Pseudomonas sp. DS10‐129, Pseudomonas sp. DS9‐119 and Acinetobacter sp. DS5‐74 emulsified xylene, benzene, n‐hexane, Bombay High crude oil, kerosene, gasoline, diesel fuel and olive oil. The first five of the above isolates had the highest emulsification activity and crude oil degradation ability and were selected for the preparation of a mixed bacterial consortium, which was also an efficient biosurfactant producing oil emulsifying and degrading culture. During this study, biosurfactant production and emulsification activity were detected in Moraxella sp., Flavobacterium sp. and in a mixed bacterial consortium, which have not been reported before.     

Production and partial characterization of biosurfactant produced by Streptomyces sp. R1

The present study focused on developing a wild-type actinomycete isolate as a model for a non-pathogenic filamentous producer of biosurfactants. A total of 33 actinomycetes isolates were screened and their extracellular biosurfactants production was evaluated using olive oil as the main substrate. Out of 33 isolates, 32 showed positive results in the oil spreading technique (OST). All isolates showed good emulsification activity (E₂₄) ranging from 84.1 to 95.8%. Based on OST and E₂₄ values, isolate R1 was selected for further investigation in biosurfactant production in an agitated submerged fermentation. Phenotypic and genotypic analyses tentatively identified isolate R1 as a member of the Streptomyces genus. A submerged cultivation of Streptomyces sp. R1 was carried out in a 3-L stirred-tank bioreactor. The influence of impeller tip speed on volumetric oxygen transfer coefficient (k _L a), growth, cell morphology and biosurfactant production was observed. It was found that the maximum biosurfactant production, indicated by the lowest surface tension measurement (40.5 ± 0.05 dynes/cm) was obtained at highest k _L a value (50.94 h⁻¹) regardless of agitation speed. The partially purified biosurfactant was obtained at a concentration of 7.19 g L⁻¹, characterized as a lipopeptide biosurfactant and was found to be stable over a wide range of temperature (20–121 °C), pH (2–12) and salinity [5–20% (w/v) of NaCl].

     

泡菜水中产生物表面活性剂酵母菌株的筛选

[背景]由微生物产生的生物表面活性剂(biosurfactant,BS)具有低毒性、高效性、生物可降解性等多种特性,能在一定程度上缓解化学表面活性剂所造成的环境问题,因此筛选高产、安全的BS生产菌株备受研究者的关注.[目的]从泡菜水中筛选能代谢合成药食两用型BS的微生物菌株.[方法]运用滴崩法和排油圈法从传统发酵食品泡...     

Isolation of biosurfactant-producing <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> RS29 from oil-contaminated soil and evaluation of different nitrogen sources in biosurfactant production

An efficient biosurfactant-producing native Pseudomonas aeruginosa RS29 has been isolated from crude oil contaminated soil. Isolation was followed by optimization of different factors to achieve maximum production of biosurfactant in terms of surface tension reduction (STR) and emulsification index (E24). The isolated strain produced highest biosurfactant in the presence of glycerol after 48 h of incubation at 37.5°C, with pH range of 7–8 and at salinity <0.8% (w/v). The extent of STR and the E24 of medium with different nitrogen sources were investigated and found to be maximal for sodium nitrate (26.3 mN/m, E24?=?80%) and potassium nitrate (26.4 mN/m, E24?=?79%). The production of biomass by the designated strain was found to be maximal in ammonium-nitrate-containing medium as compared to the other nitrogen sources. A kinetic study revealed that biosurfactant production is positively correlated with growth of P. aeruginosa, and highest STR was achieved (27.0 mN/m) after 44 h of growth. The biosurfactant was produced as a primary metabolite and 6 g/L crude biosurfactant was extracted by chloroform:methanol (2:1). The critical micelle concentration of the biosurfactant was 90 mg/L. The absorption bands of the FTIR spectra confirmed the rhamnolipid nature of the biosurfactant. The biosurfactant was thermostable (up to 121°C for 15 min) and could withstand a wide range of pH (2–10) and NaCl concentration (2%–10% w/v). The extracted biosurfactant had good foaming and emulsifying activities and was of satisfactory quality in terms of stability (temperature, pH and salinity) and foaming activity.     

Production of biosurfactant on crude date syrup under saline conditions by entrapped cells of Natrialba sp. strain E21, an extremely halophilic bacterium isolated from a solar saltern (Ain Salah, Algeria)

A bacterial strain E21 was isolated from a sample of water collected in the salt lake located close to Ain Salah, Algeria. The analysis of 16S rRNA gene sequence had indicated that the strain had 93 % sequence similarity with the genus Natrialba sp. strain E21 (GenBank, FR750525.1) and was considered extremely halophilic. Production of biosurfactant by the strain E21 with free and entrapped cells was investigated using soluble starch in the saline conditions. Biosurfactant synthesis was followed by measuring the surface tension and emulsifying index 9 days under optimal conditions (40 °C, pH 7). Some diffusional limitations in alginate and agar beads affected the kinetics of biosurfactant production when compared to that obtained with free cells culture. The minimum values of surface tension were 27 and 30 mN m^?1 achieved after 9 days with free and immobilized cells, respectively, while the corresponding maximum E24 values were 65.3 and 62.3 %, respectively. The re-use of bacterial cells along with the limited cell losses provided by the immobilized system might lead to significant reduction of the biosurfactant production cost.     

Anti-adhesion activity of two biosurfactants produced by <Emphasis Type="Italic">Bacillus</Emphasis> spp. prevents biofilm formation of human bacterial pathogens

In this work, two biosurfactant-producing strains, Bacillus subtilis and Bacillus licheniformis, have been characterized. Both strains were able to grow at high salinity conditions and produce biosurfactants up to 10% NaCl. Both extracted-enriched biosurfactants showed good surface tension reduction of water, from 72 to 26–30 mN/m, low critical micelle concentration, and high resistance to pH and salinity. The potential of the two lipopeptide biosurfactants at inhibiting biofilm adhesion of pathogenic bacteria was demonstrated by using the MBEC device. The two biosurfactants showed interesting specific anti-adhesion activity being able to inhibit selectively biofilm formation of two pathogenic strains. In particular, Escherichia coli CFT073 and Staphylococcus aureus ATCC 29213 biofilm formation was decreased of 97% and 90%, respectively. The V9T14 biosurfactant active on the Gram-negative strain was ineffective against the Gram-positive and the opposite for the V19T21. This activity was observed either by coating the polystyrene surface or by adding the biosurfactant to the inoculum. Two fractions from each purified biosurfactant, obtained by flash chromatography, fractions (I) and (II), showed that fraction (II), belonging to fengycin-like family, was responsible for the anti-adhesion activity against biofilm of both strains.     

A novel lipopeptide produced by a Pacific Ocean deep-sea bacterium, Rhodococcus sp. TW53

Aims: Our goal was to find a novel, biosurfactant‐producing bacterium from Pacific Ocean deep‐sea sediments. Methods and Results: An oil‐degrading biosurfactant‐producing bacterium TW53 was obtained from deep‐sea sediment, and was identified through 16S rDNA analysis as belonging to the genus Rhodococcus. It lowered the surface tension of its culture to 34·4 mN m^?1. Thin layer chromatography (TLC) showed that the crude biosurfactants of TW53 were composed of lipopeptides and free fatty acids (FA). The lipopeptides were purified with column chromatography and then hydrolysed with 6 mol l^?1 HCl. Gas chromatography‐mass spectrometry analysis showed that the hydrolyte in the hydrophobic fraction contained five kinds of FA with chain lengths of C₁₄–C₁₉, and C₁₆H₃₂O₂ was a major component making up 59·18% of the total. However, 3‐hydroxyl FA was not found, although it is usually found in lipopeptides. Silica gel TLC revealed that the hydrolyte in the hydrophilic fraction was composed of five kinds of amino acids; consistently, ESI‐Q‐TOF‐MS analysis confirmed the composition results and provided their sequence tentatively as Ala‐Ile‐Asp‐Met‐Pro. Furthermore, the yield and CMC (critical micelle concentrations) of purified lipopeptides were examined. The purified product reduced the surface tension of water to 30·7 mN m^?1 with a CMC value of 23·7 mg l^?1. These results suggest that Rhodococcus sp. TW53 produces a novel lipopeptide that we have named rhodofactin. Conclusion: The deep‐sea isolate Rhodococcus sp. TW53 was the first reported lipopeptide‐producing bacterium of this genus. The lipopeptides had novel chemical compositions. Significance and Impact of the Study: Rhodococcus sp. TW53 has potential in the exploration of new biosurfactants and could be used in bioremediation of marine oil pollution.     

Production and properties of a biosurfactant synthesized byArthrobacter protophormiae — an antarctic strain

This study reports the production of biosurfactant by a psychrophilic strain ofArthrobacter protophormiae during growth on an immiscible carbon source, w-hexadecane. The biosurfactant reduces the surface tension of the medium from 68.0 mN/m to 30.60 mN/m and exhibits good emulsification activity. The strain could grow and produce biosurfactant in the presence of high NaCl concentrations (10.0 to 100.0 g/1). Although the biosurfactant was isolated by growing the organism under psychrophilic conditions (10‡C) it exhibited stable activity over a wide range of temperature (30‡C to 100‡C). It retained its surface-active properties at p^H2 to 12. The biosurfactant was effective in recovering up to 90% of residual oil from an oil saturated sandpack column, indicating its potential value in enhanced oil recovery.