Biodegradação de 2-metilnaftaleno e fenantreno por pseudomonas aeruginosa AP029-glviia na presença de dispersante industrial em meio aquoso

Abstract

Oil stands out as one of the precursors for the production of materials, fuels and even medicines. Knowing this great importance, extraction and refining processes are frequent and due to this great exploration, accidents can happen causing spills in soils and oceans. Due to its high carcinogenicity and mutagenic aspects, the presence of some polycyclic aromatic hydrocarbons (PAHs), present in the composition of the oil, pose risks to humans and wild animals. Thus, in order to mitigate the environmental problems caused by PAHs in the event of a spill, the use of microorganisms for biodegradation has been seen as a potential solution. One factor that hinders the microbiological decomposition of PAHs is the hydrophobicity of the molecules, which is why the industry invests in the development of dispersants that reduce surface tension at the hydrocarbon/water interface. In this context, the literature has demonstrated the advantages of biosurfactants (surfactants of biological origin) in relation to surfactants from the chemical industry. The main objective of the present study is to evaluate the biodegradation capacity of 2-Methylnaphthalene and Phenanthrene (model hydrocarbons) by Pseudomonas aeruginosa AP029-GLVIIA in the presence of industrial biosurfactant using microcosm cultures. The biosurfactant provided by the company Syensqo Oil & Gas Solutions was characterized in terms of surface tension and emulsification index (E%). Biodegradation tests were carried out by varying the concentration of hydrocarbons and biosurfactant for 10 days, monitoring pH, bacterial growth and biodegradation rate, and also evaluating the degradation of the hydrocarbon mixture. The results demonstrate that the industrial biosurfactant presented satisfactory emulsification index results for toluene and lubricating oil, presenting values above 40% for concentrations of NaCl added and in small concentrations of biosurfactant, after 240 hours of cultivation. The biosurfactant, in addition to acting as a dispersant, reducing the surface tension of the hydrocarbon/water interface, acted as a carbon source for growth for Pseudomonas aeruginosa AP029-GLVIIA, thus favoring its greater growth. The bacteria was able to degrade phenanthrene (FEN) and 2-Methylnaphthalene (2-MN) obtaining degradation values of up to 61.43% and 97.22% respectively, within the same conditions, presenting a concentration of 17. 69 g/L of biosurfactant. It was also observed that the biosurfactant improved the biodegradation rate, with phenanthrene being the only variable that had a significant influence on the studied response, while for 2-MN the model showed that all variables and their interactions are significant to the proposed model. Furthermore, the model developed from the results of the statistical analysis managed to explain 92.31% of the data presented for the degradation of phenanthrene and around 98.0% for the biodegradation of 2- MN. The mixture of the two model hydrocarbons studied presented a degradation rate of 11.12% and 82.95% for phenanthrene and 2-MN respectively. The results showed that the biodegradation of PAHs by Pseudomonas aeruginosa AP029-GLVIIA was favored in the presence of the biosurfactant, with 2-MN as the preferred hydrocarbon.