Characterization of a biosurfactant produced by Peruvian strain Pseudomonas aeruginosa 6K-11

Obregon-Maldonado P.M.; Merino-Rafael F.A.; Gutiérrez-Moreno S.M. · Journal of Chemical Technology and Biotechnology (2024) · DOI: 10.1002/jctb.7583

Resumen

BACKGROUND: The oil industry has a big impact on the environment by itself and by using chemically synthesized surfactants. Biosurfactants are an ecofriendly alternative, especially rhamnolipids produced by Pseudomonas aeruginosa. Rhamnolipids in a determined concentration decrease the liquid surface tension, and this allows access oil hydrocarbon to be degraded. The objective of this research is to characterize the biosurfactant produced by the native strain P. aeruginosa 6K-11 by determining its critical micelle concentration (CMC), Krafft point, and emulsifying activity. RESULTS: Experiments were initially performed with rhamnolipid produced by P. aeruginosa 6K-11 growing on Siegmund-Wagner medium with 1% of waste oil as carbon source and at 31.26 °C, 186 rpm after 42 h of incubation. After that, the biosurfactant was purified according to acid precipitation methodology. The first conductivity measurement, 34 μS/cm, was obtained with 12.5 g/L of rhamnolipid by using an APERA conductivity meter. The rhamnolipid CMC was 5.86 g/L due to the conductivity measurements graph and 0.49 was the dissociation degree. The equations of both lines were found by the method of least squares. The rhamnolipid has produced 1.97 Units of Emulsifying Activity (UEA) and 50% stability was observed based on the E24 Index. The highest conductivity achieved under 39 °C, as calculated from a conductivity against temperature graph, was the Krafft point. CONCLUSION: These findings give important parameters to characterize the P. aeruginosa 6K-11 biosurfactant activity that can be used to accelerate oil biodegradation in bioremediation processes.

Instituciones: Universidad Nacional Mayor de San Marcos