Analysis and Characterization of Purified Levan from Leuconostoc mesenteroides ssp. cremoris and its Effects on Candida albicans Virulence Factors

[摘要] The objective of the current study is to characterize levan purified from Leuconostoc mesenteroides ssp. cremoris and the detection of its effects against the growth and virulence factors of C. albicans. The purification and characterization of levan produced by local isolates was done using thin layer chromatography (TLC) and High performance liquid chromatography (HPLC) analysis which determined and proved that purified levan is a homopolysaccharide consisting only of fructose. The determination of functional group analysis of levan was studied using Fourier transform infrared spectroscopy (FTIR). The results showed that the bond region in 857.60 cm-1 is typical to carbohydrates (identification of polysaccharides). The melting point was also determined. Levan began to liquefy at 224 ºC, and was completely melting at 330 ºC. The antifungal activity of levan was determined against fourteen isolates of Candida albicans taken from oral and vaginal specimens. The MIC for all of the C. albicans isolates was between (50 –100) mg/mL. The effects of purified levan (at sub MIC) on C. albicans virulence factors which included phospholipase, haemolysin production, biofilm formation and hyphal transition were determined. The results showed that purified levan had the ability to inhibit the virulence factors of C. albicans with significant differences compared with the control. The change in the Pz value of most isolates was recorded and turned from strong isolates to moderate isolates. On the other hand, the inhibition of haemolysin production was recorded. The highest inhibition percentage was 58.53 %, while the lowest percentage was 53.84 %. The purified levan showed inhibitory effects on C. albicans biofilm formation in microtiter plates and acrylic denture resin specimens at different incubation times of 24, 48, and 72 hours. In the microtiter plates, the highest inhibition percentage of biofilm formation was 70.58 % at a seventy-two- hour incubation time, whereas for the acrylic denture resin specimens, the highest inhibition percentage of biofilm formation was 68 % at a seventy-two-hour incubation time. Also, the inhibition of hyphal transition was recorded, and the highest inhibition percentage of hyphal transition was 59.26 %. In conclusion, purified levan showed inhibitory effects on the growth and virulence factors of C. albicans.

[学科分类] 生物科学（综合）

[关键词] Levan;Leuconostoc mesenteroides;Inhibitory effect;Candida albicans;Virulence factors