Application of a low-cost biosurfactant in heavy metal remediation processes.

The industrial interest in microbial surfactants has intensified in recent years due to the characteristics of these compounds, such as biodegradability, low toxicity, and effectiveness in removing heavy metals and hydrophobic organic compounds from soil and water. This paper describes the production of a biosurfactant by the yeast Candida tropicalis grown in distilled water with 2.5% molasses, 2.5% frying oil and 4% corn steep liquor. The production of the biosurfactant reached 27 g/l in a 50-l bioreactor with a surface tension of 30 mN/m. Surface tension and engine oil emulsification assays demonstrated the stability of biosurfactant under extreme conditions of temperature and pH as well as in the presence of NaCl. Chemical structures of the biosurfactant were identified using GC-MS and NMR. The isolated biosurfactant was characterised as an anionic molecule capable of reducing the surface tension of water from 70 to 30 mN/m at 0.5% of the critical micelle concentration, with no toxic effects on plant seeds or brine shrimp. In tests involving both the crude and isolated biosurfactant for the removal of heavy metals from contaminated sand under dynamic conditions, the removal rates for Zn and Cu ranged from 30 to 80%, while the best removal rate for Pb was 15%. Tests in packed columns also confirmed the ability of biosurfactant to remove Cu and Zn at rates ranging from 45 to 65%. However, lead was not removed under static conditions. The removal kinetics demonstrated that 30 min was sufficient for the removal of metals and a single washing with the biosurfactant achieved greater removal efficiency. The use of the biosurfactant led to a significant reduction in the electrical conductivity of solutions containing heavy metals. The present findings as well as a brief economic analysis suggest the great potential of this agent for industrial remediation processes of soil and water polluted with inorganic contaminants.

Treatment of oily effluent using a low-cost biosurfactant in a flotation system.

Fuel and lubricating oil leaks produce an oily wastewater that creates an environmental problem for industries. Dissolved air flotation (DAF) has been successfully employed for the separation of oily contaminants. Collectors constitute an auxiliary tool in the DAF process that enhances the separation efficiency by facilitating the adhesion of the contaminant particles. The use of biosurfactants as collectors is a promising technology in flotation processes, as these biomolecules are biodegradable and non-toxic. In the present study, a biosurfactant was produced from the bacteria Pseudomonas aeruginosa UCP 0992 cultivated in 0.5% corn steep liquor and 4.0% vegetable oil residue in a bioreactor at 225 rpm for 120 h, resulting in a surface tension of 26.5 mN/m and a yield of 26 g/L. The biosurfactant demonstrated stability when exposed to different temperatures, heating times, pH values and salt and was characterised as a glycolipid with a critical micelle concentration of 600 mg/L. A central composite rotatable design was used to evaluate the effect of the crude biosurfactant added to a laboratory DAF prototype on the removal efficiency of motor oil. The isolated and formulated forms of the biosurfactant were also tested in the prototype after the optimisation of the operational conditions. The results demonstrated that all forms of the biosurfactant increased the oil separation efficiency of the DAF process by 65 to 95%. In conclusion, the use of biosurfactants is a promising alternative as an auxiliary tool in flotation processes for the treatment of oily waters generated by industrial activities.

Production of a biosurfactant from Bacillus methylotrophicus UCP1616 for use in the bioremediation of oil-contaminated environments.

The aim of the present study was to produce a microbial biosurfactant for use in the bioremediation of environments contaminated with petroleum products. Bacillus methylotrophicus was isolated from seawater taken from a port area and cultivated using industrial waste as substrate (corn steep liquor and sugarcane molasses [both at 3%]). Surface tension measurements and motor oil emulsification capacity were used for the evaluation of the production of the biosurfactant, which demonstrated stability in a broad range of pH and temperature as well as a high concentration of saline, with the reduction of the surface tension of water to 29 mN/m. The maximum concentration of biosurfactant (10.0 g/l) was reached after 144 h of cultivation. The biosurfactant was considered to be a lipopeptide based on the results of proton nuclear magnetic resonance and Fourier transformed infrared spectroscopy. The tests demonstrated that the biosurfactant is innocuous and has potential for the bioremediation of soil and water contaminated by petroleum products. Thus, the biosurfactant described herein has a low production cost and can be used in environmental processes.

Use of bacterial biosurfactants as natural collectors in the dissolved air flotation process for the treatment of oily industrial effluent.

The aim of the present study was to investigate the separation of oil from water using a bench-scale DAF prototype with the addition of biosurfactants isolated from Pseudomonas cepacia CCT6659 and Bacillus cereus UCP1615. The best operating conditions for the DAF prototype were determined using a central composite rotatable design. The results demonstrated that the biosurfactants from P. cepacia and B. cereus increased the oil separation efficiency from 53.74% (using only microbubbles) to 94.11 and 80.01%, respectively. The prediction models for both DAF-biosurfactant systems were validated, showing an increase in the efficiency of the DAF process from 53.74% to 98.55 and 70.87% using the formulated biosurfactants from P. cepacia and B. cereus, respectively. The biosurfactant from P. cepacia was selected as the more promising product and used for the treatment of oily effluent from a thermoelectric plant, achieving removal rates ranging between 75.74 (isolated biosurfactant) and 95.70% (formulated biosurfactant), respectively.

Production of Biosurfactants by Pseudomonas Species for Application in the Petroleum Industry.

The production of surfactants by microorganisms has become an attractive option in the treatment of oil-contaminated environments because biosurfactants are biodegradable and less toxic than synthetic surfactants, although production costs remain high. With the aim of reducing the cost of biosurfactant production, three strains of Pseudomonas (designated P1, P2, and P3) were cultivated in a low-cost medium containing molasses and corn steep liquor as substrates. Following the selection of the best producer (P3), a rotational central composite design (RCCD) was used to determine the influence of substrates concentration on surface tension and biosurfactant yield. The biosurfactant reduced the surface tension of water to 27.5 mN/m, and its CMC was determined to be 600 mg/L. The yield was 4.0 g/L. The biosurfactant demonstrated applicability under specific environmental conditions and was able to remove 80 to 90% of motor oil adsorbed to sand. The properties of the biosurfactant suggest its potential application in bioremediation of hydrophobic pollutants.

Biosurfactants: Multifunctional Biomolecules of the 21st Century.

In the era of global industrialisation, the exploration of natural resources has served as a source of experimentation for science and advanced technologies, giving rise to the manufacturing of products with high aggregate value in the world market, such as biosurfactants. Biosurfactants are amphiphilic microbial molecules with hydrophilic and hydrophobic moieties that partition at liquid/liquid, liquid/gas or liquid/solid interfaces. Such characteristics allow these biomolecules to play a key role in emulsification, foam formation, detergency and dispersal, which are desirable qualities in different industries. Biosurfactant production is considered one of the key technologies for development in the 21st century. Besides exerting a strong positive impact on the main global problems, biosurfactant production has considerable importance to the implantation of sustainable industrial processes, such as the use of renewable resources and "green" products. Biodegradability and low toxicity have led to the intensification of scientific studies on a wide range of industrial applications for biosurfactants in the field of bioremediation as well as the petroleum, food processing, health, chemical, agricultural and cosmetic industries. In this paper, we offer an extensive review regarding knowledge accumulated over the years and advances achieved in the incorporation of biomolecules in different industries.

Applications of biosurfactants in the petroleum industry and the remediation of oil spills.

Petroleum hydrocarbons are important energy resources. However, petroleum is also a major pollutant of the environment. Contamination by oil and oil products has caused serious harm, and increasing attention has been paid to the development and implementation of innovative technologies for the removal of these contaminants. Biosurfactants have been extensively used in the remediation of water and soil, as well as in the main stages of the oil production chain, such as extraction, transportation, and storage. This diversity of applications is mainly due to advantages such as biodegradability, low toxicity and better functionality under extreme conditions in comparison to synthetic counterparts. Moreover, biosurfactants can be obtained with the use of agro-industrial waste as substrate, which helps reduce overall production costs. The present review describes the potential applications of biosurfactants in the oil industry and the remediation of environmental pollution caused by oil spills.

Evaluation antimicrobial and antiadhesive properties of the biosurfactant Lunasan produced by Candida sphaerica UCP 0995.

Different groups of biosurfactants exhibit diverse properties and display a variety of physiological functions in producer microorganisms; these include enhancing the solubility of hydrophobic/water-insoluble compound, heave metal binding, bacterial pathogenesis, cell adhesion and aggregation, quorum sensing and biofilm formation. Candida sphaerica was grown in a low cost medium, consisting of distilled water supplemented with 9% refinery residue of soybean oil and 9% corn steep liquor, for 144 h at 28°C and 150 rpm. The cell-free supernatant obtained at the end of the experiments was submitted to extraction, and afterward the biosurfactant was isolated using methanol with a yield of 9 g l(-1). The critical micelle concentration of the biosurfactant was found to be 0.25 mg ml(-1) with a surface tension of 25 mN m(-1). Several concentrations of the biosurfactant (0.625-10 mg ml(-1)) were used to evaluate its antimicrobial and antiadhesive activities against a variety of microorganisms. The biosurfactant showed antimicrobial activity against Streptococcus oralis (68%), Candida albicans (57%), and Staphylococcus epidermidis(57.6%) for the highest concentration tested. Furthermore, the biosurfactant at a concentration of 10 mg ml(-1) inhibited the adhesion between 80 and 92% of Pseudomonas aeruginosa, Streptococcus agalactiae, Streptococcus sanguis12. Inhibition of adhesion with percentages near 100% occurred for the higher concentrations of biosurfactant used. Results gathered in this study point to a potential use of the biosurfactant in biomedical applications.

Economic optimized medium for tensio-active agent production by Candida sphaerica UCP0995 and application in the removal of hydrophobic contaminant from sand.

Statistical experimental designs and response surface methodology were employed to optimize the concentrations of agroindustrial residues as soybean oil (SORR) from refinery, and corn steep liquor (CSL) from corn industry, for tensio-active agent produced by Candida sphaerica UCP 0995. Three 2(2) full factorial design were applied sequentially to investigate the effects of the concentrations and interactions of soybean oil refinery residue and corn steep liquor on the surface tension of free-cell culture broth for 144 h. Two 2(2) central composite designs and response surface methodology were adopted to derive a statistical model to measure the effect of SORR and CSL on the surface tension of the free-cell culture broth for 144 h. The regression equation obtained from the experimental data using a central composite design was solved, and by analyzing the response surface contour plots, the optimal concentrations of the constituents of the medium were determined: 8.63% v/v (≅9% v/v) of SORR and 8.80% v/v (≅9% v/v) CSL. The minimum surface tension predicted and experimentally confirmed was 25.25 mN/m. The new biosurfactant, denominated Lunasan, recovered 95% of motor oil adsorbed in a sand sample, thus showing great potential for use in bioremediation processes, especially in the petroleum industry.

Effect of medium components on the production of a biosurfactant from Candida tropicalis applied to the removal of hydrophobic contaminants in soil.

The influence of medium constituents on the production of biosurfactants by Candida tropicalis cultivated in waste frying oil was investigated according to a fractional factorial 2(5-1) design. The combined effect of the C/N(inorganic), C/Fe, C/Mg, and C/P ratios and yeast extract on surface tension reduction, biosurfactant yield, emulsification activity, and biomass were studied. The highest biosurfactant yield was reached when low C/Mg and low C/P ratio variables were combined, while the cell growth was favored by increasing the nitrogen concentration. The highest surface tension net decrease, on the other hand, was observed at low yeast extract concentration, low C/Fe, and high C/P ratios. Emulsification indices against lubrication and automobile waste oil of approximately 65 to 95% were observed. The crude biosurfactant produced in the medium--formulated with 2% waste frying oil, 0.067% NH4Cl, 0.025% MgSO4.7H2O, 0.067% KH2PO4, and 0.0026% FeCl3.6H2O--removed approximately 78 to 97% of the petroleum and motor oil adsorbed in sand samples.

Production, characterization, evaluation and toxicity assessment of a Bacillus cereus UCP 1615 biosurfactant for marine oil spills bioremediation.

In this study, Bacillus cereus was cultivated in a mineral medium composed of 2% frying oil and 0.12% peptone to produce a biosurfactant. The production was scaled up from flasks to 1.2-, 3.0- and 50-L bioreactors, where surface tension achieved 28.7, 27.5 and 32 mN/m and biosurfactant concentration 4.3, 4.6 and 4.7 g/L, respectively. The biosurfactant was characterized as anionic, while nuclear magnetic resonance, thin-layer chromatography and gas chromatography analyses revealed its lipopeptide nature. Toxicity tests showed survival rates of the fish Poecilia vivipara and the bivalve Anomalocardia brasiliana higher than 90% and 55%, respectively, thus suggesting the use of this biosurfactant in marine environment depollution. Moreover, the biosurfactant stimulated the growth of autochthonous microorganisms independently of the presence of motor oil in bioassays performed in seawater. These results demonstrate that the biosurfactant is biocompatible and has potential for industrial-scale production and application to bioremediation of oil spills-polluted marine environment.

Studies of the cell surface properties of Candida species and relation to the production of biosurfactants for environmental applications.

In practical bioremediation of petroleum pollution, treatment systems often use soil, sand, and other aquifer porous media besides water solutions. The distribution of the microbial cell also plays an important role in the whole process of bioremediation; therefore, the adhesion ability of cells to porous media is one of the key factors influencing the efficiency of treatment. The probable modes of hydrocarbon uptake in cells of Candida were studied based on data for cell hydrophobicity, emulsifying activity, surface tension, and interfacial tension of the cell-free culture medium. Six Candida strains were cultivated in insoluble and soluble substrates for 144 h, including n-hexadecane, soybean oil, ground-nut oil refinery residue, corn steep liquor, and glucose. The results obtained showed the potential of yeasts for application in the removal of hydrophobic compounds. Depending the strain and substrate used the adhesion ability of yeast cells and the production of surfactants and emulsifiers can take place simultaneously, thus increasing the efficiency of bioremediation treatment of petroleum pollution. The application of crude biosurfactants separated from the yeast cells was also demonstrated by tests of removal of petroleum and the derivate motor oil adsorbed in sand samples. Biosurfactants produced in low-cost medium were able to remove 90% of the hydrophobic contaminants.

Mouthwash containing a biosurfactant and chitosan: An eco-sustainable option for the control of cariogenic microorganisms.

The aim of the present study was to determine the antimicrobial action and toxicity of mouthwashes formulated with a biosurfactant, chitosan of a microbial origin and peppermint (Mentha piperita) essential oil (POE). Chitosan was extracted from the biomass of a fungus from the order Mucorales grown in yam bean broth. Three biosurfactants produced by Pseudomonas aeruginosa UCP 0992 (PB), Bacillus cereus UCP 1615 (BB) and Candida bombicola URM 3718 (CB) were tested. Six mouthwashes were prepared, the active ingredients of which were the biosurfactant, chitosan and POE. The minimum inhibitory concentration (MIC) was determined for the test substances separately, in combinations and in the mouthwash formulas. The toxicity of the mouthwashes was tested using MTT (3-(4,5-dimethylthiazole-2-il)-2,5-diphenyltetrazolium bromide) for the L929 (mouse fibroblast) and RAW 264.7 (mouse macrophage) cell lines. All substances tested had a MIC for cariogenic microorganisms. The combinations of the CB and PB biosurfactants with chitosan demonstrated an additive effect on the majority of microorganisms tested. The toxicity of the mouthwashes was significantly lower than that of the commercial mouthwash. The present findings demonstrate that mouthwashes containing natural products constitute a safe, effective, natural alternative to commercially available mouthwashes for the control of oral microorganisms.

Application of biosurfactants and chitosan in toothpaste formulation.

The aim of the present study was to formulate toothpastes containing biosurfactants and either fungal chitosan or sodium fluoride and evaluate the cytotoxicity, antimicrobial action and inhibition potential against biofilm formed by Streptococcus mutans. Chitosan was extracted from the biomass of the fungus Mucorales. We tested biosurfactants produced by Pseudomonas aeruginosa UCP 0992 (PB), Bacillus metylotrophicus UCP 1616 (BB) and Candida bombicola URM 3718 (CB). Fractional inhibitory concentration analysis was performed to determine the type of interaction between the compounds. Six toothpaste were prepared, the active ingredients of which were the biosurfactants, chitosan or sodium fluoride. The cytotoxicity tests were performed using the 3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay for the L929 (mouse fibroblast) and RAW 264.7 (mouse macrophage) cell lines. The toothpastes were tested with regard to pH, consistency and foaming capacity. The inhibition of biofilm was investigated by applying the toothpaste to biofilm formed in modified artificial saliva for 24 h at 37 °C in anaerobiosis. All substances had a minimum inhibitory concentration (MIC) for S. mutans. The combinations of CB and PB with chitosan had an additive effect against S. mutans, whereas BB combined with chitosan had an indifferent effect. The toothpastes were non-toxic. The formulations had pH around 9, spreading capacity between 8 and 17 mm and foaming capacity between 63 and 95%. All formulations inhibited the cellular viability of S. mutans in the biofilm, with similar results compared to the commercial toothpaste tested. The present results show that the formulations suggested are promising when compared to a commercial tooth paste.

Saponins and microbial biosurfactants: Potential raw materials for the formulation of cosmetics.

The cosmetic industry is currently one of the fasting growing sections of the economy in many countries. The recent tendency toward the use of cosmetics of a natural origin has driven the industry to seek alternatives to synthetic components in the formulation of products. Biosurfactants are natural compounds that have considerable potential for application in the formulation of safe, effective cosmetics as a replacement for commonly used chemical tensioactive agents. The present review provides essential information on the physicochemical and biological properties of saponins and microbial biosurfactants employed in cosmetic products, with a focus on the use of these natural compounds in shampoos, addressing the current state of research and patents involving biosurfactants for this purpose. The challenges and prospects of this cosmetic application are also discussed. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1482-1493, 2018.

Recovery of contaminated marine environments by biosurfactant-enhanced bioremediation.

The need to remediate areas contaminated by petroleum products has led to the development of novel technologies for treating such contaminants in a non-conventional manner, that is, without the use of chemical or physical methods. Biosurfactants are amphipathic biomolecules produced by microorganisms that can be used in bioremediation processes in environments contaminated by petroleum products due to their excellent tensioactive properties. The aim of the present study was to produce a biosurfactant from Pseudomonas aeruginosa UCP 0992 cultivated in 0.5% corn steep liquor and 4.0% vegetable oil residue in a 1.2-L bioreactor employing a central composite rotatable design to optimize the cultivation conditions for maximum yield. The best results were achieved with aeration rate of 1.0 vvm and 3.0% inoculum at 225 rpm for 120 h, resulting in a surface tension of 26.5 mN/m and a biosurfactant yield of 26 g/L. Kinetic and static assays were then performed with the biosurfactant for the removal of motor oil adsorbed to sand, with removal rates around 90% and 80%, respectively, after 24 h. Oil degradation experiments with the bacterium and the combination of the bacterium and biosurfactant were also conducted to simulate the bioremediation process in sand and seawater samples (duration: 75 and 30 days, respectively). In both cases, oil degradation rates were higher than 90% in the presence of the biosurfactant and the producing species, indicating the potential of the biomolecule as an adjuvant in petroleum decontamination processes in the marine environment.

Response Surface Methodology for Optimizing the Production of Biosurfactant by Candida tropicalis on Industrial Waste Substrates.

Biosurfactant production optimization by Candida tropicalis UCP0996 was studied combining central composite rotational design (CCRD) and response surface methodology (RSM). The factors selected for optimization of the culture conditions were sugarcane molasses, corn steep liquor, waste frying oil concentrations and inoculum size. The response variables were surface tension and biosurfactant yield. All factors studied were important within the ranges investigated. The two empirical forecast models developed through RSM were found to be adequate for describing biosurfactant production with regard to surface tension (R2 = 0.99833) and biosurfactant yield (R2 = 0.98927) and a very strong, negative, linear correlation was found between the two response variables studied (r = -0.95). The maximum reduction in surface tension and the highest biosurfactant yield were 29.98 mNm-1 and 4.19 gL-1, respectively, which were simultaneously obtained under the optimum conditions of 2.5% waste frying oil, 2.5%, corn steep liquor, 2.5% molasses, and 2% inoculum size. To validate the efficiency of the statistically optimized variables, biosurfactant production was also carried out in 2 and 50 L bioreactors, with yields of 5.87 and 7.36 gL-1, respectively. Finally, the biosurfactant was applied in motor oil dispersion, reaching up to 75% dispersion. Results demonstrated that the CCRD was suitable for identifying the optimum production conditions and that the new biosurfactant is a promising dispersant for application in the oil industry.

Yeasts and bacterial biosurfactants as demulsifiers for petroleum derivative in seawater emulsions.

Oil sludge or waste generated in transport, storage or refining forms highly stable mixtures due to the presence and additives with surfactant properties and water forming complex emulsions. Thus, demulsification is necessary to separate this residual oil from the aqueous phase for oil processing and water treatment/disposal. Most used chemical demulsifiers, although effective, are environmental contaminants and do not meet the desired levels of biodegradation. We investigated the application of microbial biosurfactants as potential natural demulsifiers of petroleum derivatives in water emulsions. Biosurfactants crude extracts, produced by yeasts (Candida guilliermondii, Candida lipolytica and Candida sphaerica) and bacteria (Pseudomonas aeruginosa, Pseudomonas cepacia and Bacillus sp.) grown in industrial residues, were tested for demulsification capacity in their crude and pure forms. The best results obtained were for bacterial biosurfactants, which were able to recover about 65% of the seawater emulsified with motor oil compared to 35-40% only for yeasts products. Biosurfactants were also tested with oil-in-water (O/W) and water-in-oil (W/O) kerosene model emulsions. No relationship between interfacial tension, cell hydrophobicity and demulsification ratios was observed with all the biosurfactants tested. Microscopic illustrations of the emulsions in the presence of the biosurfactants showed the aspects of the emulsion and demulsification process. The results obtained demonstrate the potential of these agents as demulsifiers in marine environments.

Candida lipolytica UCP0988 Biosurfactant: Potential as a Bioremediation Agent and in Formulating a Commercial Related Product.

The aim of the present study was to investigate the potential application of the biosurfactant from Candida lipolytica grown in low-cost substrates, which has previously been produced and characterized under optimized conditions as an adjunct material to enhance the remediation processes of hydrophobic pollutants and heavy metals generated by the oil industry and propose the formulation of a safe and stable remediation agent. In tests carried out with seawater, the crude biosurfactant demonstrated 80% oil spreading efficiency. The dispersion rate was 50% for the biosurfactant at a concentration twice that of the CMC. The biosurfactant removed 70% of motor oil from contaminated cotton cloth in detergency tests. The crude biosurfactant also removed 30-40% of Cu and Pb from standard sand, while the isolated biosurfactant removed ~30% of the heavy metals. The conductivity of solutions containing Cd and Pb was sharply reduced after biosurfactants' addition. A product was prepared through adding 0.2% potassium sorbate as preservative and tested over 120 days. The formulated biosurfactant was analyzed for emulsification and surface tension under different pH values, temperatures, and salt concentrations and tested for toxicity against the fish Poecilia vivipara. The results showed that the formulation had no toxicity and did not cause significant changes in the tensoactive capacity of the biomolecule while maintaining activity demonstrating suitability for potential future commercial product formulation.

Biosurfactants: Promising Molecules for Petroleum Biotechnology Advances.

The growing global demand for sustainable technologies that improves the efficiency of petrochemical processes in the oil industry has driven advances in petroleum biotechnology in recent years. Petroleum industry uses substantial amounts of petrochemical-based synthetic surfactants in its activities as mobilizing agents to increase the availability or recovery of hydrocarbons as well as many other applications related to extraction, treatment, cleaning, and transportation. However, biosurfactants have several potential applications for use across the oil processing chain and in the formulations of petrochemical products such as emulsifying/demulsifying agents, anticorrosive, biocides for sulfate-reducing bacteria, fuel formulation, extraction of bitumen from tar sands, and many other innovative applications. Due to their versatility and proven efficiency, biosurfactants are often presented as valuable versatile tools that can transform and modernize petroleum biotechnology in an attempt to provide a true picture of state of the art and directions or use in the oil industry. We believe that biosurfactants are going to have a significant role in many future applications in the oil industries and in this review therefore, we highlight recent important relevant applications, patents disclosures and potential future applications for biosurfactants in petroleum and related industries.