An Integrated Analysis of Intracellular Metabolites and Virulence Gene Expression during Biofilm Development of a Clinical Isolate of <i>Candida tropicalis</i> on Distinct Surfaces

• Main Authors: Maria Michela Salvatore, Angela Maione, Luisa Albarano, Elisabetta de Alteriis, Federica Carraturo, Anna Andolfi, Francesco Salvatore, Emilia Galdiero, Marco Guida
• Format: Article
• Language: English
• Published: MDPI AG 2021-08-01
• Series: International Journal of Molecular Sciences
• Subjects: biofilm; <i>Candida tropicalis</i>; medical devices; metabolomics; gene expression
• Online Access: https://www.mdpi.com/1422-0067/22/16/9038
• ISSN: 1661-6596; 1422-0067

Emergence of <i>Candida tropicalis</i>, which causes potential life-threatening invasive candidiasis, is often associated with colonization of medical devices as biofilm. Biofilm plays an important role in the virulence of the pathogen because of its complex structure, which provides resistance to conventional antimicrobials. In this study, the metabolic response of a clinical strain of <i>C. tropicalis</i> colonizing three distinct surfaces (polytetrafluoroethylene (PTFE), polystyrene, and polycarbonate) as well as the expression of virulence and stress related genes (<i>ALS3, Hsp21</i>, <i>SAP1</i>, <i>SAP2</i>, <i>SAP3</i>, and <i>CYR1</i>), were explored. Our results showed that lesser biofilm was developed on PTFE compared to polystyrene and polycarbonate. GS-MS metabolic analysis identified a total of 36 metabolites in the intracellular extract of cells grown on polystyrene, polycarbonate, and PTFE, essentially belonging to central carbon metabolism, amino acids, and lipids metabolism. The metabolic analysis showed that saturated and unsaturated fatty acids are preferentially produced during biofilm development on polycarbonate, whereas trehalose and vitamin B6, known as cellular protectors against a variety of stressors, were characteristic of biofilm on PTFE. The results of the transcriptomic analysis consider the different degrees of colonization of the three substrates, being <i>CYR1</i>, which encodes the component of signaling pathway of hyphal formation-cAMP-PKA, downregulated in PTFE biofilm compared to polycarbonate or polystyrene biofilms, while <i>Hsp21</i> was upregulated in concomitance with the potential unfavorable conditions for biofilm formation on PTFE. Overall, this work provides new insights into the knowledge of <i>C. tropicalis</i> biofilm development on surfaces of medical relevance in the perspective of improving the management of <i>Candida</i> infections.