Exopolysaccharide analysis of biofilm‐forming Candida albicans

Abstract

Aim: The major objective of the study was to analyse exopolysaccharide produced by a biofilm forming‐clinical strain of Candida albicans. Methods and Results: The biofilm‐forming ability of C. albicans recovered from infected intrauterine devices (IUDs) was evaluated using XTT (2,3‐bis[2‐methoxy‐4‐nitro‐5‐sulfophenyl]‐2H‐tetrazolium‐5‐carboxanilide) reduction assay. The morphological characteristics of the biofilm were assessed using scanning electron microscopy (SEM), atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). Biochemical characterization of the exopolysaccharide was carried out by gel permeation chromatography, gas chromatography (GC), Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. Microscopic studies of C. albicans biofilm revealed complex, heterogeneous three‐dimensional structure, in which yeast cells and hyphal elements were entrenched within exopolysaccharides matrix. Chromatographic analysis data indicated C. albicans exopolysaccharide (c. 300 kDa) to be made up of four major sugar units. The FTIR spectrum revealed specific absorbance of O–H, C–H, O=C=O, C=O, C–N and C–C ring stretching. 1H and 13C NMR data showed the presence of β (1→6) and β (1→3) linkages in the exopolysaccharide chain that were assigned to α‐d‐glucose and β‐d‐glucose, α‐d‐mannose, α‐l‐rhamnose and N‐acetyl glucosamine (β‐d‐GlcNAc), respectively. Conclusions: Study suggested the production of a water soluble c. 300 kDa exopolysaccharide by C. albicans made up of glucose, mannose, rhamnose and N‐acetyl glucosamine subunits. Significance and Impact of the Study: The study could assist in the development of novel therapeutics aimed at disrupting C. albicans biofilms that will translate into improved clearance of Candida‐related infections.

Sustained Release of a Novel Anti-Quorum-Sensing Agent against Oral Fungal Biofilms

“…Our data clearly showed a dose-dependent decrease in biofilm thickness, which could be explained by the differences in cell morphology observed by light microscopy, as well as differences in the amounts of EPS in samples treated with SRM-S-8 compared to controls. C. albicans biofilms secrete a thick layer of EPS, which is associated with immobilization and inhibition of antifungal drug penetration into the biofilm (46,47). A notable reduction in EPS production in biofilms exposed to SRM-S-8 can be related to the reduced biomass and modified morphology of the cells.…”

Biofilm formation by zygomycetes: quantification, structure and matrix composition

“…Immunolabelling studies have further revealed the presence of galactomannan, galactosaminogalactan and a-1,3 glucans (Beauvais et al, 2007;Loussert et al, 2010). C. albicans biofilms usually contain glucose (16-32.2 %), hexosamine (3.3 %), proteins (5 %), phosphorus (0.5 %) and uronic acid (0.1 %) as well as mannose, rhamnose and galactose in the matrix (Al-Fattani & Douglas, 2006;Baillie & Douglas, 2000;Lal et al, 2010). However, C. tropicalis biofilm matrix comprises mainly hexosamine (27.4 %), with smaller amounts of other carbohydrates (3.3 %, including 0.5 % glucose), protein (3.3 %) and phosphorus (0.2 %) (Al-Fattani & Douglas, 2006).…”

“…By contrast, glucose is the major component of Candida and Aspergillus fumigatus biofilms (Al-Fattani & Douglas, 2006;Baillie & Douglas, 2000;Beauvais et al, 2007;Lal et al, 2010;Silva et al, 2009). In A. fumigatus biofilms, the EPS consists of glucose (74 %), mannitol (18 %), trehalose (3 %), glycerol (5 %), and melanin and proteins (2 %) (Beauvais et al, 2007).…”

Biosynthesis of UDP-4-keto-6-deoxyglucose and UDP-rhamnose in Pathogenic Fungi Magnaporthe grisea and Botryotinia fuckeliana

“…The N-linked glycan portion of this glycoprotein is composed of mannose and rhamnose and is believed to be involved in the adherence of the fungus to dermal tissue (34). The opportunistic human pathogen Candida albicans, the causal agent of candidiasis, when grown under conditions that favor biofilm production secretes a large exopolysaccharide composed of rhamnose, mannose, glucose, and glucosamine (35). However, under normal growth conditions, the yeast and hyphal forms lack rhamnose.…”