Qualitative and quantitative estimation of beta-glucan (β-1,3-glucan) extracted from keratitis causing Fusarium spp.

Keratitis is a corneal inflammation caused by invasion of the epithelium, stroma, and endothelium. Fusarium is the predominant fungal pathogen associated with keratitis, and β-1,3-glucan is an important component in fungi's cell walls. The study involved 15 isolates for β-1,3-glucan quantification using enzyme-linked immunosorbent assay (ELISA) and Congo red assays, followed by characterization using thin layer chromatography (TLC) and Fourier Transform Infrared (FT-IR) spectroscopy. Quantitative expression of genes contributing to β-glucan synthesis was done for Fusarium solani species complex (FSSC) isolates and immunomodulatory effects of mycelia and extracted β-glucan were studied. Among the 2 major groups FSSC and Fusarium dimerum species complex (FDSC) studied, the β-glucan concentration lies in a narrow range in FSSC but in the case of FDSC, the β-glucan concentration varies highly among the studied isolates. Also, this study reported the expression of glucanases and glucan synthase genes in two FSSC isolates with the highest and lowest β-glucan content. Lastly, it was shown that FDSC (CSH-4) beta- glucan & mycelia induced more TNF alpha production compared to FSSC (CSH5). The scarcity of investigations on the regulation of β-glucan synthesis makes this study very important to understand Fusarium infection and management.