Preparation and antibacterial activity studies of degraded polysaccharide selenide from Enteromorpha prolifera

•Degraded polysaccharide selenide was synthesized from sodium selenite and degraded polysaccharide with the catalysis of nitric acid.•Antibacterial activity experiments of degraded polysaccharide selenide and degraded polysaccharide were tested.•LEP and Se-LEP were characterized by UV, IR, and thermal stability. Polysaccharide extracted from Enteromorpha prolifera possessed excellent biological activities, but its molecular weight was greatly high which influenced the activity. Organic Se had higher biological activities and was safer than inorganic Se species. In the present study, degraded polysaccharide selenide (Se-LEP) was synthesized from sodium selenite and degraded polysaccharide (LEP) with the catalysis of nitric acid. The preparation conditions of LEP and Se-LEP were optimized by orthogonal experiments. The selenite ester group was formed, and the selenium content was 1335.27µg/g. The thermal stability of Se-LEP decreased. LEP had less inhibitory effects on bacteria and plant pathogenic fungi. Se-LEP had stronger inhibitory effect on Eschetichia coli, and weaker inhibitory effect on Staphylococcus aureus than polysaccharide selenide (Se-EP). Se-LEP also had better inhibitory effects on plant pathogenic fungi.