Simple method for quantification of anionic biosurfactants in aqueous solutions

Gabriele Sass; Marie-Christine Groleau; Eric Déziel; David A Stevens

doi:10.3389/fbioe.2023.1253652

Simple method for quantification of anionic biosurfactants in aqueous solutions

Front Bioeng Biotechnol. 2023 Oct 10:11:1253652. doi: 10.3389/fbioe.2023.1253652. eCollection 2023.

Authors

Gabriele Sass¹, Marie-Christine Groleau², Eric Déziel², David A Stevens^{1

3}

Affiliations

¹ California Institute for Medical Research, San Jose, CA, United States.
² Institut National de la Recherche Scientific-Centre Armand-Frappier Santé Biotechnologie, Laval, QC, Canada.
³ Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, United States.

Abstract

Biosurfactants are microbial products that have applications as cleaning agents, emulsifiers, and dispersants. Detection and quantification of biosurfactants can be done by various methods, including colorimetric tests, high performance liquid chromatography (HPLC) coupled to several types of detectors, and tests that take advantage of biosurfactants reducing surface tension of aqueous liquids, allowing for spreading and droplet formation of oils. We present a new and simple method for quantifying biosurfactants by their ability, on paper, to reduce surface tension of aqueous solutions, causing droplet dispersion on an oiled surface in correlation with biosurfactant content. We validated this method with rhamnolipids, surfactin, sophorolipids, and ananatoside B; all are anionic microbial surfactants. Linear ranges for quantification in aqueous solutions for all tested biosurfactants were between 10 and 500 µM. Our method showed time-dependent biosurfactant accumulation in cultures of Pseudomonas aeruginosa strains PA14 and PAO1, and Burkholderia thailandensis E264. Mutants in genes responsible for surfactant production showed negligible activity on oiled paper. In summary, our simple assay provides the opportunity to quantify biosurfactant contents of aqueous solutions, for a diversity of surfactants, by means readily available in any laboratory.

Keywords: Burkholderia; Pseudomonas; assay; biosurfactant; quantification; rhamnolipids.

Grants and funding

These studies were funded by ongoing support by the Foundation for Research in Infectious Diseases (FRID, grant 8201). Research on biosurfactants in the Déziel laboratory is supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) under award number RGPIN-2020-06771. The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.