Actividad interfacial en el Sistema Dodecano-Agua de las mutaciones 6 y 12 de la proteína transmembranal a (OMPA) provenientes de la Bacteria Escherichia Coli.

Abstract

The effort to develop products that do not threaten the environment has led researchers to seek new alternatives that can replace petroleum products, among these are biosurfactants, which represent an alternative to replace conventional surfactants. Currently, it has been shown that certain types of proteins are potential biosurfactants, within these are transmembrane protein OmpA, which has been widely investigated (Aguilera-Segura et al., 2016) and through random modifications in its gene has shown better performance. In a previous study by the research group of the Universidad de los Andes, this protein was cloned and random modifications were made to the gene, obtaining that mutants 6 and 12 were potential biosurfactants, having a lower interfacial value than the OmpA protein, these tests were made with the protein extract (unpurified). The interfacial tension affects the mass transfer through the liquid-liquid interface and the stability of dispersed systems, when this tension is reduced with a biosurfactant, the molecule of the dispersed phase is dispersed in the continuous phase in the form of small droplets (Zhao et al., 2022). This project used E. coli BL21 with mutations 6 and 12 that were inducible with isopropyl-β-D-thiogalactopyranoside (IPTG), overexpressing the histidine-tagged mutations (encoded on plasmid PET6xHN-N), which were purified by chromatography by affinity, the interfacial tension and its ability to stabilize emulsions at the dodecane-water interface were evaluated. Using proteins as surfactants has positive effects on interfacial tension since when using wash 2 of both mutations, it exhibited a decrease in tension of 9.10 dyn/cm for mutation 6 and 15.15 dyn/cm for mutation 12, unlike tween 20 (petroleum-derived surfactant) that had a decrease in interfacial tension of 22.00 dyn/cm by means of the hanging drop method. With the turbiscan stability index and backscattering light analysis, it was found that the emulsion was more stable with mutation 6 compared to the emulsion prepared with mutation 12.