Investigating the role of biosurfactant-producing lactobacilli isolated from the vagina in preventing biofilm formation by pathogenic Candida strains / Jakline Nelson Saddik Hanalla ; Supervised Mohamed Abdelhalim Ramadan , Ramy Karam Aziz , Meselhy Salah Mansy

Thesis (Ph.D.) - Cairo University - Faculty of Pharmacy - Department of Microbiology and Immunology

The vaginal microbiota is dominated by lactic acid bacteria (LAB), notably lactobacilli, which are well adapted to the vaginal environment. They form a critical line of defense against pathogenic microorganisms that have the ability to form biofilms, such as Candida species. This study aimed to investigate the anti-adhesion capabilities of vaginal Lactobacillus isolates against biofilms formed by pathogenic Candida species. When the extracellular biosurfactant activities of culture supernatants from 120 Lactobacillus isolates were evaluated by the oil-spreading method, clear spreading zones were recognized. Biofilm formation was quantified by the crystal violet plate assay, and different isolates exhibited anti-adhesion activity that ranged from 65.6 to 74.4% inhibition against Candida spp. biofilm. Liquid chromatography high-resolution electrospray ionization mass spectrometry (LC-HRESIMS) identified biosurfactants, extracted from three representative Lactobacillus isolates, as surfactin, iturin and lichenysin. Finally, the distribution of representative genes from six different biosynthetic clusters, related to the production of different biosurfactants, was investigated by the polymerase chain reaction. In conclusion, surfactin, iturin and lichenysin were identified for the first time in vaginal Lactobacillus spp.These biosurfactants, which showed strong anti-adherence activity may be used as promising antibiofilm agents in equipment care to prevent vaginal infections by pathogenic Candida spp. with the prospect of reducing nosocomial infections

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