Fuel and oil spills during the exploration, refining, and distribution of oil and petrochemicals are primarily responsible for the accumulation of organic pollutants in the environment. The reduction in contamination caused by hydrocarbons, heavy metals, oily effluents, and particulate matter generated by industrial activities and the efficient recovery of oil at great depths in an environmentally friendly way pose a challenge, as recovery and cleaning processes require the direct application of surface-active agents, detergents, degreasers, or solvents, often generating other environmental problems due to the toxicity and accumulation of these substances. Thus, the application of natural surface-active agents is an attractive solution. Due to their amphipathic structures, microbial surfactants solubilize oil through the formation of small aggregates (micelles) that disperse in water, with numerous applications in the petroleum industry. Biosurfactants have proven their usefulness in solubilizing oil trapped in rock, which is a prerequisite for enhanced oil recovery (EOR). Biosurfactants are also important biotechnological agents in anti-corrosion processes, preventing incrustations and the formation of biofilms on metallic surfaces, and are used in formulations of emulsifiers/demulsifiers, facilitate the transport of heavy oil through pipelines, and have other innovative applications in the oil industry. The use of natural surfactants can reduce the generation of pollutants from the use of synthetic detergents or chemical solvents without sacrificing economic gains for the oil industry. Therefore, investments in biotechnological processes are essential. It is predicted that, in the not-too-distant future, natural surfactants will become viable from an economic standpoint and dominate the world market. The application of biosurfactants in these settings would lead to industrial growth and environmental sustainability. The main goal of this paper is to provide an overview of diverse applications of biosurfactants on environmental remediation, petroleum biotechnology, and the oil industry through a scientific literature review.

Oil spills occur during different operations in the energy sector, such as crude oil transport, tank filling and cleaning, and fueling. Such spills are one of the major causes of the accumulation of oil derivatives in the environment, requiring the remediation of soil and marine environments. The production of a biosurfactant by Starmerella bombicola ATCC 222214 was maximized by investigating the effect of different carbon/nitrogen sources and culture conditions. The mineral medium selected for its production was supplemented with 2.0% potato peel flour, 5.0% waste canola frying oil, and 0.20% urea. The culture conditions were a 200 rpm shaking speed, a fermentation time of 180 h, and a 4.0% inoculum size. The yield of isolated biosurfactant was 7.72 g/L. The emulsification rates of heavy oil and motor oil were 65.55 and 95.00%, respectively, indicating an affinity for complex hydrocarbons. In stability tests performed at different pH values, temperatures, and NaCl concentrations, the surface tension ranged from 27.14 to 31.08 mN/m. The critical micelle concentration was 2.0 g/L, at which the surface tension was 33.26 mN/m. The biosurfactant was composed of 6,6-dimethoxy-octanoic acid and azelaic acid, and it exhibited low toxicity to Brassica oleracea and Solanum lycopersicum. In the kinetic test, the biosurfactant allowed for the removal of 82.30%, 96.65%, and 98.25% of exhaust motor oil from sand, silty soil, and clay soil, while in the static test in packed columns, the removal yields were 66.62%, 63.03%, and 58.45%, respectively. The biosurfactant produced in this study is promising for environmental remediation applications in the energy sector.

Spills involving fuels and lubricating oils in industrial environments caused by the fueling of machines, inadequate storage and the washing of equipment are significant sources of environmental pollution, impacting soil and water bodies. Such incidents alter the microbiological, chemical and physical properties of affected environments. The use of biosurfactants is an effective option for the cleaning of storage tanks and the remediation of contaminated soils and effluents. The scope of this work was to assess the production and application of a Starmerella bombicola ATCC 22214 biosurfactant to remediate marine and terrestrial environment polluted by oil. The production of the biosurfactant was optimized in terms of carbon/nitrogen sources and culture conditions using flasks. The performance of the biosurfactant was tested in clayey soil, silty soil, and standard sand, as well as smooth surfaces and industrial effluents contaminated with oils (fuel oils B1 for thermal power generation, diesel, and motor oil). The ideal culture medium for the production of the biosurfactant contained 2% glucose and 5% glycerol, with agitation at 200 rpm, fermentation for 180 h and a 5% inoculum, resulting in a yield of 1.5 g/L. The biosurfactant had high emulsification indices (86.6% for motor oil and 51.7% for diesel) and exhibited good stability under different pH values, temperatures and concentrations of NaCl. The critical micelle concentration was 0.4 g/L, with a surface tension of 26.85 mN/m. In remediation tests, the biosurfactant enabled the removal of no less than 99% of motor oil from different types of soil. The results showed that the biosurfactant produced by Starmerella bombicola is a promising agent for the remediation of environments contaminated by oil derivatives, especially in industrial environments and for the treatment of oily effluents.

Corrosion is the deterioration of metals due to environmental exposure. Commercial inhibitors used to control corrosion often contain heavy metal salts, which are highly toxic to both the environment and human health. A biosurfactant produced by the bacterium Pseudomonas cepacia CCT 6659 was tested as a corrosion inhibitor on carbon steel and galvanized iron surfaces. Matrices based on plant ingredients with different compositions were tested in a laboratory-constructed accelerated corrosion chamber (ACC) simulating a critical maritime atmosphere in conditions of 40 °C, 5% NaCl, and 100% humidity. The most stable matrix was selected for biosurfactant incorporation in different concentrations, expressed as critical micellar concentration (CMC), and was applied to metal surfaces to evaluate its ability to inhibit corrosion. Additionally, to evaluate the potential of the biosurfactant as a low-toxicity corrosion inhibitor additive in paint systems, iron and carbon steel samples were coated with three biosurfactant-containing commercial paints and subjected to critical atmospheric conditions for testing coating effectiveness. The formulation containing vegetable resin as a plasticizer, oleic acid, ethanol, and CaCO₃ was chosen to incorporate the biosurfactant. The addition of the biosurfactant at twice its CMC led to a reduction in carbon steel sample mass loss from 123.6 to 82.2 g/m², while in the galvanized iron plates, the mass loss decreased from 285.9 to 226.7 g/m² at the same biosurfactant concentration. When supplemented with the biosurfactant, the alkyd resin-based paint (A) ensured less mass loss in samples (46.0 g/m²) compared to the control without biosurfactant (58.0 g/m²). Using the paint formulated with oil-based resin (B), the mass loss decreased from 53.0 to 24.1 g/m², while with that based on petroleum derivatives (C), it decreased from 82.2 to 27.6 g/m². These results confirm the feasibility of using biosurfactants in biodegradable coatings, reducing the need for commercial corrosion inhibitors.

Human development has led to increased production of oil and gas, mainly as energy sources, which, however, are responsible for contamination and metal corrosion in industrial, marine, and terrestrial environments. Lubricating oil, in particular, is widely used in generators and industrial machines in the electric sector and is responsible for contamination not only in industrial environments but also in many terrestrial and aquatic ecosystems. In this context, this study aimed to apply the Starmerella bombicola ATCC 222214 biosurfactant to inhibit metal corrosion in seawater and in an Accelerated Corrosion Chamber (ACC). For this purpose, its toxicity against the microcrustacean Artemia salina, its dispersion capacity, and its ability to promote oil biodegradation in a saline environment were investigated. The biosurfactant, when applied at twice its Critical Micellar Concentration (CMC), caused low mortality (30.0%) of microcrustaceans in a saline environment, and, in its crude form, the biosurfactant ensured the dispersion of no less than 77.56% of residual engine oil in seawater. Oil biodegradation by autochthonous microorganisms reached 94.39% in the presence of the biosurfactant in seawater. Furthermore, the biosurfactant, when used at twice its CMC, acted satisfactorily as a corrosion inhibitor by reducing the mass loss of galvanized iron specimens (plates) in seawater in a static system to only 0.36%. On the other hand, when the biosurfactant was added at the CMC as an atmospheric corrosion inhibitor, the reduction in mass loss of carbon steel plates treated in the ACC was 17.38% compared to the control containing only a biodegradable matrix based on vegetable resin. When the biosurfactant was incorporated into different paints applied to galvanized iron plates placed in contact with the salt spray produced in the ACC, the best result was obtained using the biomolecule at a concentration of 3% in the satin paint, ensuring a plate mass loss (29.236 g/m²) that was almost half that obtained without surfactant (52.967 g/m²). The study indicated the use of yeast biosurfactant as a sustainable alternative in combating the contamination of marine environments and metal corrosion, with the aim of preserving the environment and improving the quality of life in aquatic and terrestrial ecosystems.