Fermentation,Physicochemical Properties, Biological Activities Of Polyphenols Produced By Lachnum YMU50

The fermentation condition optimization, purification, physicochemical properties and biological activities of Lachnum YMU50extracellular polyphenols were studied in this paper and results were as follows:A high polyphenol-producing strain Lachnum YMU50was obtained by UV mutagenesis of protoplast. The extracellular polyphenols and biomass yield of Lachnum YMU50mutant increased by71.11%and83.47%, respectively. The optimal fermentation conditions of YUM50were as follows:sucrose20g/L, peptone5g/L, magnesium chloride0.81g/L, tyrosine0.01g/L and pH6.The effect of sodium nitroprusside (SNP) on biomass and extracellular polyphenols accumulation of Lachnum YMU50and its antioxidant defense system had been studied. Results were as follows:application of SNP at low concentration could accelerate the growth of Lachnum YMU50mycelium, increase Lachnum YMU50PAL activity and promote the Lachnum YMU50total extracellular polyphenols (LTEP) accumulation. Furthermore, application of SNP at high concentration significantly inhibited the growth of Lachnum YMU50, and was adverse to the accumulation of biomass and LTEP. Application of SNP at low concentration significantly increased the CAT, SOD and APX activities in Lachnum YMU50mycelium, decreased H2O2and MDA contents, and induced and activated the antioxidant defense system of Lachnum YMU50. However, application of SNP at high concentration reduced the CAT, SOD and APX activities in Lachnum YMU50mycelium, and increased the H2O2and MDA contents, and damaged the antioxidant defense system of Lachnum YMU50.Results showed that polyamide resin with80-100mesh provide the best static adsorption and desorption properties. LTEP was purified by using polyamide resin with80-100mesh. Results of single factor experiments showed that the optimal adsorption conditions were:sample concentration2mg/mL, sample pH4, sample flow rate1BV/h. the optimal dynamic desorption conditions were:ethanol concentration20%, desorption flow rate1BV/h, the amount of ethanol500mL, pH8.5. A response surface analysis was made for further optimization of desorption conditions and the results were:ethanol concentration18%, desorption flow rate0.98BV/h, the amount of ethancol600mL, pH9. The purity of the obtained LTEP reached75.45%under the optimal adsorption and desorption condition. UV, IR and GC-MS analysis of LTEP purified by polyamide resin were performed. Results showed that LTEP had a typical maximum absorption peak at270nm and340nm. IR indicated that LTEP had characteristic absorption peaks of polyphenols at3354.360cm-1and1048.762cm-1. GC-MS analysis showed LTEP included benzoic acid,3,3’,4’,5,7-pentahydroxyflavone,2-bromo-4-hydroxy-5-methoxy-phenyl acetic acid,3-bromo-5-ethoxy-4-hydroxybenzaldehyde etc.The scavenging effect of LTEP on O2-·, DPPH,·OH and NO2-were determined to evaluate the antioxidant ability of LTEP. When the concentration of LTEP was2mg/mL, the scavenging rate of O2-·、DPPH·、·OH、and NO2-were76.43%、72.7%、55.56%、and59.4%, respectively. Antibacterial effect of LTEP suggested that it had the strongest antibacterial effect against Staphylococcus aureus among the tested bacterials, MIC of Staphylococcus aureus, S. cerevisiae, E. coli, Salmonella were0.05,0.1,0.1and0.2mg/mL, respectively.