In vitro efficacy of the lipopeptide biosurfactant surfactin-C₁₅ and its complexes with divalent counterions to inhibit Candida albicans biofilm and hyphal formation

Abstract

Surfactin is a type of cyclic lipopeptide biosurfactant implicated in a wide range of applications. Although its antimicrobial activity has been characterized, its effect on Candida albicans physiology remains to be elucidated. The present study evaluated the influence of surfactin-C₁₅ (SF) and its complexes with divalent counterions on C. albicans biofilm formation and preformed biofilms. The SF and metal(II)-SF complexes inhibited biofilm formation and reduced the metabolic activity of mature biofilms in a concentration-dependent manner. The same concentrations of the compounds studied dislodged preexisting biofilms grown on polystyrene plates. Moreover, SF and its metal(II) complexes reduced the mRNA expression of hypha-specific genes HWP1, ALS1, ALS3, ECE1 and SAP4 without exhibiting significant growth inhibition. Further research showed that the compounds tested reduced cellular surface hydrophobicity (CSH). These results suggest that SF and metal(II)-SF complexes could be used as anti-biofilm agents against C. albicans hypha-related infections in clinical practice.

Keywords:

• Candida albicans
• biofilms
• biosurfactants
• surfactin
• morphogenesis
• hypha-specific genes

Acknowledgements

We thank Prof. Henny van der Mei (University of Groningen and University Medical Center Groningen, the Netherlands) for generously providing C. albicans strain P_HWP1-GFP.

Disclosure statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Additional information

Funding

This work was supported by the National Science Centre, Poland, project 2018/02/X/NZ6/02201.

Notes on contributors

Tomasz Janek

TJ conceived the project, contributed to the experimental design, performed most of the experiments, interpreted the data, and wrote the manuscript. KD performed the RT-PCR experiments. TJ and AD contributed the reagents, materials, and analysis tools. All authors read and approved the final version of the manuscript.