Research On Characterization Of Wheat Bran Polysaccharides Before And After Probiotic Fermentation And Its Effects On Antioxidant Function And Intestinal Health Of Zebrafish

In this study,water-soluble polysaccharides（WBP）and FWBP were extracted from Wheat bran before and after probiotic fermentation.The structure characteristics,activity and function of wheat bran polysaccharide before and after fermentation were investigated.The main contents and conclusions are as follows:（1）Effects of probiotic fermentation on physicochemical characteristics of WBPThe effects of fermentation on physicochemical characteristics of WBP were studied by separation and purification of unfermented and fermented wheat bran polysaccharide.The crude polysaccharides extracted from WB and FWB were purified by anion exchange chromatography on DEAE-52 cellulose columns,and four polysaccharide fractions were obtained:WBP-1,WBP-2,FWBP-1 and FWBP-2.The fractions with the highest yield were collected and used in subsequent study.The structural properties of wheat bran polysaccharides before and after fermentation were characterised by fourier transform-infrared（FT-IR）,high performance liquid chromatography（HPLC）and gel permeation chromatography（GPC）.FT-IR showed that both WBP-1 and FWBP-1 had typical absorption peaks for polysaccharides,with FWBP-1 having broader absorption peaks at 3400,1600,1400 and 1040 cm^-1.The monosaccharide composition showed that WBP-1 and FWBP-1were both mainly composed of glucose,xylose,arabinose,galactose and mannose,but there were differences in their proportions and the presence of fucose in FWBP-1.GPC analysis the Mw of FWBP-1 was markedly lower after the fermentation.（2）Comparative study on the effect of wheat bran polysaccharide on antioxidant function of zebrafish embryos before and after probiotic fermentationThe antioxidant activities of wheat bran polysaccharide before and after fermentation were evaluated by reducing power,DPPH and scavenging ability of hydroxyl radical.The effects of WBP-1 and FWBP-1 on the antioxidant function of zebrafish embryos were compared using the oxidative stress model induced by normal zebrafish embryos and AAPH embryos,respectively.It was found that the reducing power and free radical scavenging ability of FWBP-1 was significantly higher than that of WBP-1（P<0.05）.The ROS production,lipid peroxidation rate and cell death of zebrafish embryos treated by FWBP-1were significantly lower than those treated by WBP-1 at 200μg/m L,the activities of CAT,SOD and GSH-Px in FWBP-1 group were significantly higher than those in WBP-1 group（P<0.05）.At the concentration of 50μg/m L,FWBP-1 significantly alleviated ROS production than WBP-1（P<0.05）.（3）Effect of wheat bran polysaccharide on intestinal peristalsis of zebrafish before and after probiotic fermentationZebrafish larvae were used as a model to evaluate the intestinal peristalsis of WBP-1and FWBP-1.The results showed that the promotion of intestinal motility in zebrafish was significantly stronger with FWBP-1 than with WBP-1 at concentrations of 10 and 20μg/m L（P<0.05）.Furthermore,loperamide hydrochloride was used to induce intestinal motility inhibition of zebrafish,we found that at a concentration of 20μg/m L,the relief of intestinal motility inhibition in zebrafish was stronger with FWBP-1 than with WBP-1（P<0.05）.（4）Effects of feeding wheat bran polysaccharides before and after fermentation on growth performance and intestinal health of zebrafishStudy on the effects of wheat bran polysaccharide on growth performance and intestinal health of zebrafish before and after probiotic fermentation using zebrafish as an animal model.Healthy,35-day-old zebrafish of similar weight were selected for the trial.The experimental rats were divided into 5 groups:basal diet（control group）,basal diet+500mg/kg WBP-1 group,basal diet+1000 mg/kg WBP-1 group,basal diet+500 mg/kg FWBP-1and basal diet+1000 mg/kg FWBP-1 group.Six replicates of 10 fish per replicate per group for a trial period of 56 days.The results showed that the intestinal villus height of zebrafish in FWBP-1 group was significantly higher than that in WBP-1 group,the relative abundance of Proteobacteria of FWBP-1 was significantly lower than that of WBP-1,and the relative abundance of Bacteroidetes,Actinomycetes and Firmicutes was significantly higher than that of WBP-1 at 500 mg/kg supplemental level（P<0.05）.At 1000 mg/kg,The WG and SGR of zebrafish in FWBP-1 group were significantly higher than those in WBP-1,while FCR was significantly lower than that in WBP-1（P<0.05）;the m RNA expression of p38,Nrf2,CAT,GST,TJP1α,Mucin2.1,Mucin5.1,MMP9 and defensin1 in the intestine of adult zebrafish was significantly higher with FWBP-1 than with WBP-1（P<0.05）;the relative abundance of the phylum Proteobacteria in FWBP-1 was significantly lower than that of WBP-1,and the relative abundance of the phylum Actinobacteria and Firmicutes was significantly higher than that of WBP-1;the abundance of Aeromonas in FWBP-1 group was significantly lower than that in WBP-1 group（P<0.05）.In summary,the probiotic fermentation modified the basic structural characteristics and improved the in vitro antioxidant properties of wheat bran polysaccharides.The fermented wheat bran polysaccharides exhibited superior effects on improving intestinal antioxidant function and intestinal health of zebrafish.