Evaluation of antibacterial properties of sulfated polysaccharide extracted from green alga Ulva intestinalis and its ability to inhibit polyphenol oxidase enzyme of western white shrimp (Litopenaeus vannamei)

Marine polysaccharides are natural bioactive compounds with valuable applications. In the current study, sulfated polysaccharide from green alga Ulva intestinalis was extracted using water-based solvents, and some of its properties such as functional groups, antibacterial activity, and its ability to inhibit the western white shrimp polyphenol oxidase enzyme were measured. The results of Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of sulfate-containing functional groups in the polysaccharide. Sulfated polysaccharide in both concentrations of 25 and 50 mg/mL showed antibacterial activity against 2 strains of gram-positive bacteria Micrococcus luteus and Staphylococcus aureus and 2 strains of gram-negative bacteria Escherichia coli and Salmonella typhimurium (P<0.05). Also, this combination with a concentration of 1.5% after 1 and 3 minutes showed the highest ability in inhibiting the activity of the western white shrimp polyphenol oxidase enzyme with 63.03 and 48.74%, respectively, compared to other concentrations (0.05>P). In general, according to the results of the present study, the use of sulfated polysaccharide obtained from green alga U. intestinalis is suggested in the shrimp processing industry.