Analysis of Rhamnolipid Biosurfactants Produced Through Submerged Fermentation Using Orange Fruit Peelings as Sole Carbon Source

The fermentative production of rhamnolipid biosurfactant from Pseudomonas aeruginosa MTCC 2297 was carried out by submerged fermentation using various cost-effective waste materials such as orange peelings, carrot peel waste, lime peelings, coconut oil cake, and banana waste. The orange peel was found to be the best substrate generating 9.18 g/l of rhamnolipid biosurfactant with a surface tension reduction up to 31.3 mN/m. The production was growth independent, and optimum conditions were standardized. The emulsifying activity was highest against kerosene (73.3%). Rhamnolipid components were purified and separated by ethyl acetate extraction, preparative silica gel column chromatography, high-performance liquid chromatography and thin-layer chromatography. The major rhamnolipid components were characterized, by fast atom bombardment mass spectrometry, as a mixture of dirhamnolipids and monorhamnolipids.     

Exopolysaccharides and Antimicrobial Biosurfactants Produced by Paenibacillus macerans TKU029

Paenibacillus macerans TKU029 can produce exopolysaccharides (EPSs; 3.46 g/L) and a biosurfactant (1.78 g/L) in a medium with 2 % (w/v) squid pen powder as the sole carbon/nitrogen source. The biosurfactant can reduce the surface tension of water from 72.30 to 35.34 mN/m at a concentration of 2.76 g/L and reach an emulsification index of 56 % after a 24-h reaction with machine oil. This biosurfactant is stable at 121 °C for 20 min, over a pH range from 3 to 11, and in <5 % salt solutions. It also shows significant antimicrobial activity, which remains active after treatment at 121 °C and at pH values from 4 to 10, against Escherichia coli BCRC13086, Staphylococcus aureus BCRC10780, Fusarium oxysporum BCRC32121 and Aspergillus fumigatus BCRC30099. Furthermore, human skin shows from 37.3 to 44.3 % hydration after being treated with TKU029 EPSs for 180 min. These results imply that EPSs and the biosurfactant from this strain have potential in cosmetics, for removal of oil contamination, and as antimicrobial agents.     

Production of a Bioemulsifier with Potential Application in the Food Industry

Biosurfactants are of considerable interest due to their biodegradability, low degree of toxicity, and diverse applications. However, the high production costs involved in the acquisition of biosurfactants underscore the need for optimization of the production process to enable viable application on an industrial scale. The aims of the present study were to select a species of Candida that produces a biosurfactant with the greatest emulsifying potential and to investigate the influence of components of the production medium and cultivation conditions. Candida utilis achieved the lowest surface tension (35.53 mN/m), best emulsification index (73 %), and highest yield (12.52 g/l) in a medium containing waste canola frying oil as the carbon source and ammonium nitrate as the nitrogen source. The best combination of medium components and cultivation conditions was 6 % (w/v) glucose, 6 % (w/v) waste canola frying oil, 0.2 % (w/v) ammonium nitrate, 0.3 % (w/v) yeast extract, 150 rpm, 1 % inoculum (w/v), and 88 h of fermentation. The greatest biosurfactant production and the lowest surface tension were achieved in the first 24 h of production, and the maximum biomass production was recorded at 72 h. The biosurfactant produced from C. utilis under the conditions investigated in the present study has a potential to be a bioemulsifier for application in the food industry.     

Interactive optimization of biosurfactant production by Paenibacillus alvei ARN63 isolated from an Iranian oil well

The potential of an indigenous bacterial strain isolated from an Iranian oil field for the production of biosurfactant was investigated in this study. After isolation, the bacterium was characterized to be Paenibacillus alvei by biochemical tests and 16S ribotyping. The biosurfactant, which was produced by this bacterium, was able to lower the surface tension of media to 35 mN/m. Accordingly, thin layer chromatography (TLC) and FT-IR has been carried out to determine compositional analysis of the produced biosurfactant. After all the tests related to characterization of the biosurfactant produced by the isolated bacterium, it was characterized as lipopeptide derivative. The combination of central composite rotatable design (CCRD) and response surface methodology (RSM) was exploited to optimize biosurfactant production. Therefore, variations of four impressive parameters, pH, temperature, glucose and salinity concentrations were selected for optimization of growth conditions. The empirical model developed through RSM in terms of effective operational factors mentioned above was found to be adequate to describe the biosurfactant production. A maximum reduction in surface tension was obtained under the optimal conditions of 13.03 g/l glucose concentration, 34.76 °C, 51.39 g/l total salt concentration and medium pH 6.89.     

First Report of a Lipopeptide Biosurfactant from Thermophilic Bacterium Aneurinibacillus thermoaerophilus MK01 Newly Isolated from Municipal Landfill Site

A biosurfactant-producing thermophile was isolated from the Kahrizak landfill of Tehran and identified as a bacterium belonging to the genus Aneurinibacillus. A thermostable lipopeptide-type biosurfactant was purified from the culture medium of this bacterium and showed stability in the temperature range of 20–90 °C and pH range of 5–10. The produced biosurfactant could reduce the surface tension of water from 72 to 43 mN/m with a CMC of 1.21 mg/mL. The strain growing at a temperature of 45 °C produces a substantial amount of 5 g/L of biosurfactant in the medium supplemented with sunflower oil as the sole carbon source. Response surface methodology was employed to optimize the biosurfactant production using sunflower oil, sodium nitrate, and yeast extract as variables. The optimization resulted in 6.75 g/L biosurfactant production, i.e., 35 % improved as compared to the unoptimized condition. Thin-layer chromatography, FTIR spectroscopy, ¹H-NMR spectroscopy, and biochemical composition analysis confirmed the lipopeptide structure of the biosurfactant.     

Production and Properties of a Surface-Active Lipopeptide Produced by a New Marine Brevibacterium luteolum Strain

Microbial-derived surfactants are molecules of great interest due to their environmentally friendly nature and low toxicity; however, their production cost is not competitive when compared to synthetics. Marine microorganisms are exposed to extremes of pressure, temperature, and salinity; hence, they can produce stable compounds under such conditions that are useful for industrial applications. A screening program to select marine bacteria able to produce biosurfactant using low-cost substrates (mineral oil, sucrose, soybean oil, and glycerol) was conducted. The selected bacterial strain showed potential to synthesize biosurfactants using mineral oil as carbon source and was identified as Brevibacterium luteolum. The surface-active compound reduced the surface tension of water to 27 mN m^?1 and the interfacial tension (water/hexadecane) to 0.84 mN m^?1 and showed a critical micelle concentration of 40 mg L^?1. The biosurfactant was stable over a range of temperature, pH, and salt concentration and the emulsification index (E₂₄) with different hydrocarbons ranging from 60 to 79 %. Structural characterization revealed that the biosurfactant has a lipopeptide nature. Sand washing removed 83 % of crude oil demonstrating the potential of the biosurfactants (BS) for bioremediation purposes. The new marine B. luteolum strain showed potential to produce high surface-active and stable molecule using a low-cost substrate.     

Production of Microbial Rhamnolipid by Pseudomonas Aeruginosa MM1011 for Ex Situ Enhanced Oil Recovery

Recently, several investigations have been carried out on the in situ bacteria flooding, but the ex situ biosurfactant production and addition to the sand pack as agents for microbial enhanced oil recovery (MEOR) has little been studied. In order to develop suitable technology for ex situ MEOR processes, it is essential to carry out tests about it. Therefore, this work tries to fill the gap. The intention of this study was to investigate whether the rhamnolipid mix could be produced in high enough quantities for enhanced oil recovery in the laboratory scale and prove its potential use as an effective material for field application. In this work, the ability of Pseudomonas aeruginosa MM1011 to grow and produce rhamnolipid on sunflower as sole carbon source under nitrogen limitation was shown. The production of Rha-C₁₀-C₁₀ and Rha₂-C₁₀-C₁₀ was confirmed by thin-layer chromatography and high-performance liquid chromatography analysis. The rhamnolipid mixture obtained was able to reduce the surface and interfacial tension of water to 26 and 2 mN/m, respectively. The critical micelle concentration was 120 mg/L. Maximum rhamnolipid production reached to about 0.7 g/L in a shake flask. The yield of rhamnolipid per biomass (Y _RL/x ), rhamnolipid per sunflower oil (Y _RL/s ), and the biomass per sunflower oil (Y _x/s ) for shake flask were obtained about 0.01, 0.0035, and 0.035 g g^?1, respectively. The stability of the rhamnolipid at different salinities, pH and temperature, and also, its emulsifying activity has been investigated. It is an effective surfactant at very low concentrations over a wide range of temperatures, pHs, and salt concentrations, and it also has the ability to emulsify oil, which is essential for enhanced oil recovery. With 120 mg/L rhamnolipid, 27 % of original oil in place was recovered after water flooding from a sand pack. This result not only suggests rhamnolipids as appropriate model biosurfactants for MEOR, but it even shows the potential as a biosurfactant of choice for actual MEOR applications.     

Synthesis,Characterization, and Oil Recovery Application of Biosurfactant Produced by Indigenous <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> WJ-1 Using Waste Vegetable Oils

A bacterial strain was isolated and cultured from the oil excavation areas in tropical zone in northern China. The biochemical characteristics and partial sequenced 16S rRNA gene of isolate, WJ-1, was identical to those of cultured representatives of the species Pseudomonas aeruginosa. This bacterium was able to produce a type of biosurfactant. Compositional analysis revealed that the extracted biosurfactant was composed of high percentage lipid (∼74%, w/w) and carbohydrate (∼20%, w/w) in addition to a minor fraction of protein (∼6%, w/w). The best production of 50.2 g/l was obtained when the cells were grown on minimal salt medium containing 6.0% (w/v) glucose and 0.75% (w/v) sodium nitrate supplemented with 0.1% (v/v) element solution at 37 °C and 180 rpm after 96 h. The optimum biosurfactant production pH value was found to be 6.0–8.0. The biosurfactant of WJ-1, with the critical micelle concentration of 0.014 g/L, could reduce surface tension to 24.5 mN/m and emulsified kerosene up to EI₂₄ ≈95. The results obtained from time course study indicated that the surface tension reduction and emulsification potential was increased in the same way to cell growth. However, maximum biosurfactant production occurred and established in the stationary growth phase (after 90 h). Thin layer chromatography, Fourier transform infrared spectrum, and mass spectrum analysis indicate the extracted biosurfactant was affiliated with rhamnolipid. The core holder flooding experiments demonstrated that the oil recovery efficiency of strain and its biosurfactant was 23.02% residual oil.     

Cr(III) and Cr(VI) Removal from Aqueous Solutions by Cheaply Available Fruit Waste and Algal Biomass

This study compared the effectiveness of different biosorbents, viz. materials commonly present in natural treatment systems (Scenedesmus quadricauda and reed) and commonly produced fruit wastes (orange and banana peel) to remove Cr(III) and Cr(VI) from a synthetic wastewater simulating tannery wastewater. The Cr(III) removal efficiency followed the order S. quadricauda?>?orange peel?>?banana peel?>?reed, whereas the Cr(VI) removal followed the order banana peel?>?S. quadricauda?>?reed?>?orange peel. The chromium biosorption kinetics were governed by the intraparticle diffusion mechanism. Isotherm data obtained using the different biosorbents were fitted to the Langmuir, Freundlich, and SIPS models, revealing that the experimental data followed most closely the monolayer sorption theory-based Langmuir model than the other models. The maximum Cr(III) sorption capacity, calculated using the Langmuir model, was found to be 12 and 9 mg/g for S. quadricauda and orange peel, respectively, and the maximum Cr(VI) sorption capacity calculated for banana peel was 3 mg/g. The influence of biosorbent size, pH, solid–liquid ratio, and competing ions were examined for Cr(III) biosorption by S. quadricauda and orange peel and for Cr(VI) sorption by banana peel. The solution pH was found to be the most influential parameter affecting the biosorption process: whereas pH 5 was found to be optimum for maximum removal of Cr(III), Cr(VI) was best removed at a pH as low as 3. Interference to chromium sorption by various ions revealed that Cr(III) binding onto orange peel occurs through electrostatic forces, whereas Cr(VI) binding onto banana peel through non-electrostatic forces.     

Evaluation of Cashew Apple Juice for Surfactin Production by Bacillus subtilis LAMI008

Bacillus subtilis LAMI008 strain isolated from the tank of Chlorination at the Wastewater Treatment Plant on Campus do Pici in Federal University of Ceará, Brazil has been screened for surfactin production in mineral medium containing clarified cashew apple juice (MM-CAJC). Results were compared with the ones obtained using mineral medium with glucose PA as carbon source. The influence on growth and surfactin production of culture medium supplementation with yeast extract was also studied. The substrate concentration analysis indicated that B. subtilis LAMI008 was able to degrade all carbon sources studied and produce biosurfactant. The highest reduction in surface tension was achieved with the fermentation of MM-CAJC, supplemented with yeast extract, which decreased from 58.95?±?0.10 to 38.10?±?0.81 dyn cm^?1. The biosurfactant produced was capable of emulsifying kerosene, achieving an emulsification index of 65%. Surfactin concentration of 3.5 mg L^?1 was obtained when MM-CAJC, supplemented with yeast extract, was used, thus indicating that it is feasible to produce surfactin from clarified cashew apple juice, a renewable and low-cost carbon source.     

Bioconversion of Sodium Dodecyl Sulphate to Rhamnolipid by Pseudomonas aeruginosa: A Novel and Cost-Effective Production Strategy

The utility of rhamnolipids in industry is currently limited due to the high constraints in its economic production. In this scenario, the novel utility of sodium dodecyl sulphate (SDS) as carbon source could serve as promising cost-effective strategy. Screening of effective SDS biodegraders led to the isolation of Pseudomonas aeruginosa S15 capable of concomitant SDS degradation and biosurfactant synthesis. SDS-based rhamnolipid production was proved on SDS minimal agar plates using cetyl trimethylammonium bromide–methylene blue method and optimised in SDS-based minimal salt (SBS) medium. SDS proved to be an ideal carbon source for rhamnolipid synthesis with a high substrate to product conversion rate yielding 6.9 g/l of rhamnolipids from 1 g/l SDS in 5 days. Fast atom bombardment mass spectroscopy analysis of the purified biosurfactant proved the presence of mono- and di-rhamnolipids, viz., Rha-C₁₀-C₁₀, Rha-C₁₀-C₁₂ and Rha-Rha-C₁₀-C₁₀ with surface active properties. The secreted rhamnolipids were not utilised by S15 as a carbon source, but it caused a dispersion of bacterial biofilms in SBS medium. To the best of our knowledge, this is the first report on bioconversion of synthetic detergent to biodetergent. This SDS-based novel methodology presents a more economised mode of rhamnolipid synthesis utilising SDS as sole carbon source.     

Comparative study of biosurfactant produced by microorganisms isolated from formation water of petroleum reservoir

Biosurfactant produced by Pseudomonas aeruginosa, Bacillus subtilis and Rhodococcus erythropolis that isolated from the formation water of Chinese petroleum reservoir has been compared in surface abilities and oil recovery. Maximum biosurfactant production reached to about 2.66 g/l and the surface tension of liquid decreased from 71.2 to 22.56 mN/m using P. aeruginosa. Three strains exhibited a good ability to emulsify the crude oil, and biosurfactant of P. aeruginosa attained an emulsion index of 80% for crude oil which was greater than other strains. Stability studies were carried out under the extreme environmental conditions, such as high temperature, pH, salinity and metal ions. Results showed an excellent resistance of all biosurfactants to retain their surface-active properties at extreme conditions. It was found that the biosurfactants from three isolated bacteria showed a good stability above pH of 5, but at lower pH (from 1 to 5) they will harmfully be affected. They were able to support the condition up to 20 g/l salinity. P. aeruginosa biosurfactant was even stable at the higher salinity. Regarding temperature, all produced biosurfactants demonstrated a good stability in the temperature up to 120 °C. But stability of three biosurfactants was affected by monovalent and trivalent ions. Oil recovery experiments in physical simulation showed 7.2-14.3% recovery of residual oil after water flooding when the biosurfactant of three strains was added. These results suggest that biosurfactants of these indigenous isolated strains are appropriate candidates for enhanced oil recovery with a preference to biosurfactant of P. aeruginosa.     

Production of Microbial Surfactants from Oily Sludge-Contaminated Soil by Bacillus subtilis DSVP23

The indigenous microbial community utilizing aliphatic, aromatic, and polar components from the oily sludge as sole source of carbon and energy was selected from the soil samples of Ankleshwar, India for biosurfactant production. Evaluation of biosurfactant production was done using screening assays such as surface tension reduction, hemolytic activity, emulsification activity, drop-collapse assay, and cell surface hydrophobicity studies. Maximum biosurfactant (6.9?g/l) production was achieved after 5?days of growth from Bacillus subtilis DSVP23 which was identified by 16S RNA technique (NCBI GenBank accession no. EU679368). Composition of biosurfactant showed it to be lipopeptide in nature with 15.2% protein content and 18.0% lipid content. Functional group analysis was also done by using Fourier transform infrared spectroscopy which showed it to be a protein-bound lipid thereby imparting them special properties. Analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometric and nuclear magnetic resonance revealed that the major constituents of lipopeptide are leucine and isoleucine. Gas chromatographic analysis data indicated that oily sludge components of chain length C₁₂?CC₃₀ and aromatic hydrocarbons were degraded effectively by B. subtilis DSVP23 after 5?days of incubation. These results collectively points toward the importance of B. subtilis DSVP23 as a potential candidate for bioremediation studies.     

Candida Biofilm Disrupting Ability of Di-rhamnolipid (RL-2) Produced from Pseudomonas aeruginosa DSVP20

Biosurfactant produced from Pseudomonas aeruginosa DSVP20 was evaluated for its potential to disrupt Candida albicans biofilm formed on polystyrene (PS) surfaces in this investigation. P. aeruginosa DSVP20 exhibited optimum production of biosurfactant (5.8 g?L^?1) after 96 h of growth with an ability to reduce surface tension of the aqueous solution from 72 to 28 mN?m^?1. Analysis of purified biosurfactant with FT-IR, ¹H and ¹³C NMR and MALDI-TOF MS revealed it to be di-rhamnolipid (RL-2) in nature. Biofilm disrupting ability of RL-2 (0.16 mg?mL^?1) on Candida cells when checked using XTT reduction assay revealed that about 50 % of the cells remain adhered to 96-well plate after 2 h of treatment, while up to 90 % reduction in pre-formed C. albicans biofilm on PS surface was observed with RL-2 (5.0 mg?mL^?1) in a dose-dependent manner. Microscopic analyses (SEM and CLSM) further confirm the influence of RL-2 on disruption of Candida biofilm extracellular matrix on PS surface which can be exploited as a potential alternative to the available conventional therapies.     

Application of Biosurfactant from Sphingobacterium spiritivorum AS43 in the Biodegradation of Used Lubricating Oil

This study aimed at investigating the application of biosurfactant from Sphingobacterium spiritivorum AS43 using molasses as a substrate and fertilizer to enhance the biodegradation of used lubricating oil (ULO). The cell surface hydrophobicity of bacteria, the emulsification activity, and the biodegradation efficiency of ULO were measured. The bacterial adhesion in the hydrocarbon test was used to denote the cell surface hydrophobicity of the used bacterial species. The results indicate a strong correlation between cell surface hydrophobicity, emulsification activity, and the degree of ULO biodegradation. The maximum degradation of ULO (62 %) was observed when either 1.5 % (w/v) of biosurfactant or fertilizer was added. The results also revealed that biosurfactants alone are capable of promoting biodegradation to a large extent without added fertilizer. The data indicate the potential for biosurfactant production by using low-cost substrate for application in the bioremediation of soils contaminated with petroleum hydrocarbons or oils.     

Production and characterization of biosurfactant from marine Streptomyces species B3

The present study demonstrates the production and properties of a biosurfactant isolated from marine Streptomyces species B3. The production of the biosurfactant was found to be higher in medium containing sucrose and lower in the medium containing glycerol. Yeast extract was the best nitrogen source for the production of the biosurfactant. The isolated biosurfactant reduced the surface tension of water to 29 mN/m. The purified biosurfactant was shown critical micelle concentrations of 110 mg/l. The emulsifying activity and stability of the biosurfactant was investigated at different salinities, pH, and temperature. The biosurfactant was effective at very low concentrations over a wide range of temperature, pH, and salt concentration. The purified biosurfactant was shown strong antimicrobial activity. The biosurfactant was produced from the marine Streptomyces sp. using non-hydrocarbon substrates such as sucrose that was readily available and not required extensive purification procedure. Streptomyces species B3 can be used for microbially enhanced oil recovery process.     

Thidiazuron-Induced Changes in Biomass Parameters,Total Phenolic Content,and Antioxidant Activity in Callus Cultures of Artemisia absinthium L.

Callus culture of Artemisia absinthium L. was established for enhanced production of phenolics and higher antioxidant activity. Callus was induced from seed-derived leaf explants, incubated on to MS media supplemented with thidiazuron (TDZ; 0.5–5.0 mg/l) either alone or in combination with α-naphthalene acetic acid (NAA; 1.0 mg/l). These callus cultures were investigated for their growth kinetics, total phenolic content, and antioxidant activity on weekly basis for a period of 49 days. Maximum dry biomass accumulation of 8.73 g/l was observed on day 42 in response to 1.0 mg/l TDZ and 1.0 mg/l NAA. Furthermore, maximum level of total phenolic content of 8.53 mg GAE/g DW and highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of 72.6 % were observed in calli formed in response to 1.0 mg/l TDZ on day 42. The results showed a positive correlation of total phenolic content and DPPH radical scavenging activity in most of the callus cultures of A. absinthium L.     

Production and Physico-chemical Characterization of a Biosurfactant Produced by <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> OBP1 Isolated from Petroleum Sludge

Pseudomonas aeruginosa strain OBP1, isolated from petroleum sludge, was used to produce biosurfactant from a modified mineral salt medium with 2% n-hexadecane as sole source of carbon. The crude biosurfactant was fractionated using TLC and HPLC. Using FTIR spectroscopy, ¹H NMR, and LC-MS analyses, the chemical structure of the purified fraction of crude biosurfactant was identified as rhamnolipid species. The LC-MS spectra show that monorhamnolipid (l-rhamnopyranosyl-β-hydroxydecanoyl-β- hydroxydecanoate, Rha-C₁₀-C₁₀) was produced in abundance with the predominant congener [M–H]⁻ ions for l-rhamnopyranosyl-l-rhamnopyranosyl-3-hydroxydecanoyl-3-hydroxydecanoate (Rha-Rha-C₁₀-C₁₀). Seven different carbon substrates and five nitrogen sources were examined for their effect on rhamnolipid production. Using n-hexadecane (20 g/l) as carbon substrate and urea along with (NH₄)₂SO₄ (2 g/l each) as nitrogen source was found to be the best, with a maximum yield of 4.8 g/l. The biosurfactant reduced the surface tension of water to 31.1 mNm⁻¹ with a critical micelle concentration of 45 mg/l. The biosurfactant showed a better emulsifying activity against a variety of hydrocarbon and achieved a maximum emulsion index of 82% for diesel. The purified biosurfactant showed a significant antibacterial activity against Staphylococcus aureus at a minimum inhibitory concentration of 8 μg/ml.     

An efficient biosurfactant-producing bacterium Pseudomonas aeruginosa MR01, isolated from oil excavation areas in south of Iran

A bacterial strain was isolated and cultured from the oil excavation areas in tropical zone in southern Iran. It was affiliated with Pseudomonas. The biochemical characteristics and partial sequenced 16S rRNA gene of isolate, MR01, was identical to those of cultured representatives of the species Pseudomonas aeruginosa. This bacterium was able to produce a type of biosurfactant with excessive foam-forming properties. Compositional analysis revealed that the extracted biosurfactant was composed of high percentages lipid (65%, w/w) and carbohydrate (30%, w/w) in addition to a minor fraction of protein (4%, w/w). The best production of 2.1 g/l was obtained when the cells were grown on minimal salt medium containing 1.2% (w/v) glucose and 0.1% (w/v) ammonium sulfate supplemented with 0.1% (w/v) isoleucine at 37 °C and 180 rpm after 2 days. The optimum biosurfactant production pH value was found to be 8.0. The MR01 could reduce surface tension to 28 mN/m and emulsified hexadecane up to E24  70. The results obtained from time course study indicated that the surface tension reduction and emulsification potential was increased in the same way to cell growth. However, maximum biosurfactant production occurred and established in the stationary growth phase (after 84 h). Fourier Transform Infrared spectrum of extracted biosurfactant indicates the presence of carboxyl, amine, hydroxyl and methoxyl functional groups. Thermogram of biosurfactant demonstrated three sharp endothermic peaks placing between 200 and 280 °C. The core holder flooding experiments demonstrated that the oil recovery efficiencies varied from 23.7% to 27.1% of residual oil.     

A New Isolate from Fusarium proliferatum (AUF-2) for Efficient Nitrilase Production

A fungal isolate from Fusarium proliferatum strain AUF-2 has been found to have a high nitrilase activity (≥1,000 U/l culture). The present work describes optimization of growth conditions and production medium to achieve maximum nitrilase production. The most effective carbon and nitrogen sources for nitrilase production were glucose and sodium nitrate, respectively. ε-Caprolactam was found to be the best inducer for maximum nitrilase production with 80 g/l wet cell biomass and 26 U/g nitrilase activity. An overall nitrilase activity of ≥2,000 U/l culture was obtained in this study, which is one of the best activities reported so far in any Fusarium strain. Chemo-profiling has shown that the strain is versatile in its ability to hydrolyze both aliphatic as well as aromatic nitriles. Efforts are being made to use the strain for biotransformation of pharmaceutical substrates.