# Physicochemical and Functional Characterizations of Biosurfactants Produced by Pseudomonas aeruginosa N33 for Oil Removal

## TL;DR

A biosurfactant from Pseudomonas aeruginosa N33 effectively removes various oils, showing promise as an eco-friendly cleaning agent.

## Contribution

Identification of a glycolipid biosurfactant from P. aeruginosa N33 with high oil-removal efficacy.

## Key findings

- The biosurfactant achieved oil-displacing ring diameters of 6.3 cm for vegetable oil and 3.8 cm for crude oil.
- It reduced contact angles of oils on glass slides from over 90° to below 20°, significantly improving wettability.
- Capillary oil removal assays confirmed its ability to strip oil films efficiently.

## Abstract

Bacterial biosurfactants have potential applications in green cleaning due to their environmental friendliness. Among all isolated bacterial strains in this study, strain N33 exhibited the most potent oil-displacing activity and was identified as Pseudomonas aeruginosa. Its biosurfactant yield was approximately 550 mg/L, and structural characterization revealed it to be a glycolipid-type biosurfactant. The oil-displacing ring diameters of the biosurfactant against vegetable oil, paraffin oil, and crude oil reached 6.3 ± 0.3 cm, 5.8 ± 0.2 cm, and 3.8 ± 0.5 cm, respectively. Its critical micelle concentration (CMC) was determined to be 150 mg/L, with a corresponding surface tension of 39.55 mN/m. Notably, this bacterial biosurfactant significantly improved interfacial wettability, reducing the contact angles of vegetable oil, paraffin oil, and crude oil on oil-wetted glass slides from 93.0°, 99.0°, and 98.8° to 10.0°, 15.0°, and 19.0°, respectively. The emulsification efficiency for the three oils was 80%, 57%, and 10%, respectively. Furthermore, capillary oil removal assays verified that the biosurfactant could efficiently strip oil films from the inner walls of capillaries. These findings demonstrate that the biosurfactant produced by P. aeruginosa strain N33 possesses considerable oil-removal efficacy, thereby providing a novel candidate for the research, development, and application of green detergents.