Valdemir Alexandre dos Santos

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.

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.

Some aspects of heavy metals contamination remediation and role of biosurfactants

Contamination by heavy metals is the result of different industrial activities. The presence of heavy metals in soil and water causes serious problems, as these materials are not biodegradable and do contaminate both biological systems and the subsoil. Biological surface-active compounds otherwise known as biosurfactants in general and rhamnolipids biosurfactants in particular have been successfully employed in the remediation of environments contaminated with heavy metal ions. The aim of the present review is to highlight potential applications of these tensioactive compounds for use in environmental heavy metals removal and bioremediation and processes involved.

Enhancement of Biosurfactant Production from Pseudomonas cepacia CCT6659 Through Optimisation of Nutritional Parameters Using Response Surface Methodology

Abstract The aim of the present study was to optimise the production of a biosurfactant by a new strain of Pseudomonas cepacia CCT6659 with aid of a combination of central composite rotatable design (CCRD) and response surface methodology (RSM). The factors selected for optimisation of the growth conditions were canola waste frying oil, corn steep liquor and NaNO3 substrate concentrations. Surface tension was chosen as the response variable. All factors studied were important within the ranges investigated. The empirical forecast model developed through RSM regarding effective nutritional factors was adequate for explaining 89 % of the variation observed in biosurfactant production. Maximal reduction in surface tension of 26 mN m–1 was obtained under the optimal conditions of 2 % waste frying oil, 3 % corn steep liquor and 0.2 % NaNO3. The accumulation of isolated biosurfactant increased from 2 g L–1 to 8.0 g L–1 under these conditions, demonstrating that the factorial design is adequate for identifying the optimal conditions for biosurfactant production.

Effect of Biosurfactant Addition in a Pilot Scale Dissolved Air Flotation System

Effluent production of oily water type has generated many environmental problems for several industries. The use of flotation as a separation process of oily waters has been described, although it has been sometimes criticized due to the toxicity of collectors. The development and use of biodegradable surfactants may enhance the further acceptance of this separation technology. This work investigated the removal of the emulsified oil products in water by dissolved air flotation (DAF) with and without the use of a biosurfactant, in pilot scale. The biosurfactant added considerable value to the process, increasing from 80.0% to 98.0% the separation efficiency.

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.

Formulation of a Commercial Biosurfactant for Application as a Dispersant of Petroleum and By-products Spilled in Oceans

Oil spills in oceans cause irreparable damage to marine life and harm the coastal populations of affected areas. It is therefore fundamental to develop treatment strategies for such spills. Currently, chemical dispersants have been used during oil spills, although these agents have been increasingly restricted due to their toxic potential. Thus, the aim of the present study was to formulate a biodegradable commercial biosurfactant for application as a dispersant. Biosurfactants are scientifically known biomolecules produced by microorganisms capable of allowing water-oil interaction. Thus, a biosurfactant was produced by the yeast Candida bombicola URM 3718 cultivated in industrial waste and formulated with the addition of a potassium sorbate preservative for fractionated sterilization (tyndallization) and the combination of fluent vaporization with the preservative. After formulation, samples were stored for 120 days, followed by surface tension, emulsification and oil dispersant tests in sea water. The results were promising for the biosurfactant formulated with the preservative, which demonstrated stability and an absence of toxicity in experiments with a marine indicator. The commercial biosurfactant was tested at different pH values, temperatures and in the presence of salt, demonstrating potential industrial application at a cost compatible with the environmental field. The formulation process developed in this research was patented in the Brazilian National Intellectual Property Institute (patent number BR1020140179631).

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.

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.