Studies On The Application Of Enzymatically Prepared Algae Oligosaccharides

Alginate oligosaccharide is a kind of oligosaccharides obtained by chemical degradation or enzymolysis of algin.Laminariajaponica is a kind of algae mainly used to extract algin,which is widely cultivated in littoral.In this paper,the methods of alkaline extraction of algin from Laminariajaponica and enzymolysis of algin to prepare alginate oligosaccharide were optimized.The enzymatic products were isolated and purified,and the constitunents were analyzed.The products were prepared through enzymolysis and acidolysis,whose bioactivities were studied.Then the effects of alginate oligosaccharides on aquiculture were studies.The results were as follows:1.The methods of alkali extraction of algin was optimized.The technological conditions were determined as follows:the extraction time of 4 h,the extraction temperature of 80 °C,the alkali concentration of 1%and the liquid-to-material ratio of 70:1 were found to be optimal for extracting algin from Laminariajaponica.The yield of algin was 30.30%.2.The effects of hydrolysis temperature,enzyme quantity and pH value,on the degree of hydrolysis of algin hydrolysed by the alginate lyases were studied by using response surface method on the basis of single factor experiment.A enzymatic hydrolysis time of 3 h,a substrate concentration of 0.7%(w/v),a pH value of 7.00,a hydrolysis temperature of 49.37?.A enzyme quantity of 0.33 U/mL,the yield of algin was 64.60%.The TLC,MS and NMR analysis showed that the composition of alginate oligosaccharides consist of three species,DP1?DP2?DP3 respectively.The main enzymatic hydrolysis products obtained from different time gradients were different,therefore,the alginate lyase was determined as endonuclease.3.The enzymic hydrolysates were separated with Bio-Gel P6 column with 0.2 mol/L ammonium bicarbonate solution as elution liquid.The alginate oligosaccharides with DP1?DP2.?DP3 were obtained.4.The antioxidant activity study showed that the product of enzymatic hydrolysis and acid hydrolysis,as well as DP3 had good scavenging activity of hydroxyl radical,ABTS,DPPH and reducing ability.The DP2 had certain scavenging activity of ABTS,DPPH,however,the effect of hydroxyl radical scavenging activity and reducing ability were not obvious.The enzymic hydrolysates and the product of acid hydrolysis,as well as DP3 have tyrosinase inhibit activity,with IC50 values of 6.05,3.68,0.75 mg/mL,respectively.5.The product of enzymatic hydrolysis and acid hydrolysis,as well as DP3 have antibacterial activity in vitro,with MIC values of 1.37 mg/mL,3.71 mg/mL,1.18 mg/mL of the inhibition of Vibrio vulnificus;The MIC values of the inhibition of JVibrio furnissii were 3.71 mg/mL,4.30 mg/mL,0.17 mg/mL,respectivly;The MIC values of the inhibition of Vibrioparahaemolyticus were 1.11 mg/mL,4.87 mg/mL,0.85 mg/mL.6.The growth performance of Pseudosciaena crocea and Rudd were significantly improved by alginate oligosaccharides,which include body weight,survival rate,full-length;The protein content in muscle,the EAA/TAA and EAA/NEAA of Pseudosciaena crocea and Rudd were significantly increased by alginate oligosaccharide;Alginate oligosaccharide also can significantly increase the activity of CAT and lysozyme in the serum of Pseudosciaena crocea,the activity of ACP,AKP,CAT and lysozyme in the serum of Rudd,the activity of protease in digestive system of Pseudosciaena crocea and Rudd.Algin was extracted from Laminaria japonica,and the components and activities of oligosaccharides were studied by enzymolysis of alginate lyase;Then the oligosaccharides prepared by enzymolysis were added into aquatic feed.This study provides a theoretical basis for the development and utilization of brown algae oligosaccharides.