The structure, characterization and immunomodulatory potential of exopolysaccharide produced by Planococcus rifietoensis AP-5 from deep-sea sediments of the Northwest Pacific

Polysaccharides derived from microorganisms exhibit diverse structures and bioactivities, making them promising candidates for the treatment of various diseases. However, marine-derived polysaccharides and their activities are relatively little known. In this work, fifteen marine strains were isolated from surface sediments in the Northwest Pacific Ocean for screening of EPS production. Planococcus rifietoensis AP-5 produced a maximum yield of EPS at 4.80 g/L. The purified EPS (referred to as PPS) had a molecular weight of 51,062 Da and contained amino, hydroxyl, and carbonyl groups as its major functional groups. PPS primarily consisted of & RARR;3)-& alpha;-DGalp-(1 & RARR; 4)-& alpha;-D-Manp-(1 & RARR; 2)-& alpha;-D-Manp-(1 & RARR; 4)-& alpha;-D-Manp-(1 & RARR; 4,6)-& alpha;-D-Glcp-(1 & RARR; 6)-& beta;-D-Galp-(1 & RARR;, with a branch consisting of T-& beta;-D-Glcp-(1 & RARR;. Additionally, surface morphology of PPS was hollow, porous, and spherelike stack. PPS primarily contained C, N, and O elements, with a surface area of 33.76 m2/g, a pore volume of 0.13 cc/g, and a pore diameter of 1.69 nm, respectively. Based on the TG curve, the degradation temperature of PPS was measured to be 247 degrees C. Furthermore, PPS demonstrated immunomodulatory activity through dosedependently upregulating the expression level of cytokines. It significantly enhanced the cytokine secretion at a concentration of 5 & mu;g/mL. To sum up, this study offers valuable insights for screening marine polysaccharidebased immunomodulators.

Automated summary

This study isolated fifteen marine strains from surface sediments in the Northwest Pacific Ocean and screened for EPS production. Planococcus rifietoensis AP-5 produced the highest yield of EPS, which was purified and characterized. The purified EPS (PPS) exhibited immunomodulatory activity and had significant surface area and pore volume. This study provides valuable insights for screening marine polysaccharide-based immunomodulators.