Structural characterization and immunostimulatory activity of a water-soluble polysaccharide from abalone(Haliotis discus hannai Ino)muscle

A water-soluble polysaccharide from abalone muscle(AMPP)was isolated.The contents of carbohydrate,protein,uronic acid,and sulfate in AMPP were 83.5%,0.5%,2.7%,and 2.6%,respectively.High-performance liquid chromatography analysis indicated that AMPP was homogeneous and had an average molecular weight of approximately 3.2 kDa.The main monosaccharides of AMPP were glucose(Glc)and mannose with a molar ratio of 99.7:0.3.The structural characteristics of AMPP were elucidated through methylation analysis,Fourier transform infrared spectroscopy,and nuclear magnetic resonance spectroscopy.The linkages of AMPP consisted of terminal,1,4-linked,1,6-linked,and 1,4,6-linked Glcp with a molar ratio of 3.1:7.2:1.0:2.5.In one repeat unit of the proposed AMPP structure,the backbone chain was composed of eight 1→4 glycosidic bonds and one 1→6 glycosidic bond,with three branch chains linked by 1→6 glycosidic bond.In addition,AMPP was found to possess potent immunostimulatory activity via rising phagocytosis of RAW264.7 cells and promoting secretion of TNF-α.

Antibacterial and antibiofi lm activity of peptide PvGBP2 against pathogenic bacteria that contaminate Auricularia auricular culture bags

Bacteria contamination in Auricularia auricular culture bags reduces yield and increases the risk of food safety.In this study,5 species of bacteria,mainly gram-positive bacteria including three species of Bacillus spp.,Arthrobacter arilaitensis and Staphylococcus warneri,were isolated and identifi ed from bacteria-contaminated A.auricular culture bags.An in silico predicted antimicrobial peptide from theβ-1,3-glucan-binding protein sequence of Penaeus vannamei,designated Pv GBP2(FLKLGRKSRYGMLKL),was screened and its antibacterial effect and mechanism of action on the isolated Bacillus spp.explored.The minimal inhibitory concentrations(MIC)of Pv GBP2 on Bacillus spp.were 15.6–31.25μg/m L.Peptide Pv GBP2 could inhibit Bacillus subtilis in A.auricular culture bags to maintain growth and yield of A.auricular.Transmission electron microscopy(TEM)revealed that Pv GBP2 kills bacteria by perforating the cell wall,destroying membrane integrity and resulting in the leakage of intracellular solutes.In addition,Pv GBP2 inhibits biofi lm formation by B.subtilis by 90.6%at 1×MIC.Thus,peptide Pv GBP2 could be potentially applied as an antibacterial agent to control bacterial infection of A.auricular cultivation and the spread of foodborne pathogens.