Fermentation, Structure, Lipid Lowering And Liver Protecting Activities Of Polysaccharides Produced By Lachnum YM281

In this paper, the yield, purification, structure, conformation and lipidlowering and liver protecting activities of polysaccharides prouduced byLachnum YM281were studied.The main results were as follow:Simultaneous improvement of the yields of intracellular polysaccharide(LIP) and extracellular polysaccharide (LEP) prouduced by Lachnum YM281in submerged cultivation was studied. Results showed that there was asignificant linear relationship between the yield of LIP (Y) and the biomass(Z): Z=12.561Y-0.0148. The yields of LIP (Y) and LEP (X) were positivelycorrelated, but the linear relationship was insignificant. Accordingly, in orderto improve the two synchronously, the two response variables (X, Y) wereintegrated into a single response variable using the desirability functions andthe fermentation conditions of LIP and LEP of Lachnum YM281wereoptimized synchronously by uniform design. Under the optimum conditions(46.6g/L glucose,14.6g/L yeast extract,6.50mg/L glycine, initial pH value=7.5,12days’ fermentation at25℃, the other factors being the same as thoseof the basic fermentation condition), the yields of LIP and LEP (2.35g/L and6.28g/L) were improved by1.4times and1.2times, respectively, comparingto those before optimization.Purification, structure, conformation of extracellular polysaccharidesproduced by Lachnum YM281were studied. A homogeneous polysaccharide(LEP-1b) was separated and purified from extracellular polysaccharides ofLachnum YM281(LEP) with DEAE-Cellulose52and SepharoseCL-6Bcolumn chromatography. LEP-1b was detected as homogeneouspolysaccharide with molecular weight of4.02×104Da by high performanceliquid gel permeation chromatography (HPGPC). On the basis of hydrolysis,methylation analysis, periodate oxidation, Smith degradation, partial acidhydrolysis, IR and NMR analysis, LEP-1b was deduced to be a(1→3)-,(1→6)-β-D-glucan. The backbone chain of LEP-1b was consisted ofβ-1,3-D-Pyran glucose residues, five glucose residues constituting a repeatunit, and each repeat unit contained a branch chain (two D-Pyran glucose residues linked by β-1,3-linkage), which was linked at C6of the backbonechain by β-1,6-linkage. The repeating unit of LEP-1b was established asConformational analysis revealed the triple helical conformation of LEP-1b.The lipid lowering and liver protecting activities of extracellularpolysaccharide produced by Lachnum YM281（LEP-1b）were studied. Resultsshowed that LEP-1b significantly lowered the serum lipids (TC, TG andLDL-C) levels, liver lipids（TC, TG and fat） levels， atherogenic index (AI),aminotransferase （ALT、AST) activities，liver MDA content and liver Indexof model mice with hyperlipidemic fatty liver, and significantly increased theserum HDL-C level, lipids excretions in excrement(TBA, TC and fat) andliver SOD activity, promoted the recovery of damaged liver tissues of modelmice with hyperlipidemic fatty liver, exhibiting a dose-effect relationship. Allthose results indicated that LEP-1b had a strong lipid lowering and liverprotecting effects on mice with hyperlipidemic fatty liver.