Structural characteristics and immune-enhancing activity of an extracellular polysaccharide produced by marine Halomonas sp. 2E1

Microbial polysaccharides from extreme environments, such as cold seeps and hydrothermal vents, usually exhibit novel structural features and diverse biological activities. In this study, an exopolysaccharide (EPS2E1) was isolated from cold-seep bacterium Halomonas sp. 2E1 and its immune-enhancing activity was evaluated. The total sugar content and protein content were determined as 83.1% and 7.9%, respectively. EPS2E1 contained mannose and glucose with the molar ratio of 3.76: 1. The molecular weight was determined to be 47.0 kDa. Structural analysis indicated that EPS2E1 was highly branched, the backbone mainly consisted of -> 2)-Man-(alpha-1 -> and -> 2, 6)-Man-(alpha-1 -> with the ratio of 2.45: 1.00. The chain also contained -> 4)-Glc-(alpha-1 ->, -> 6)-Man-(alpha-1 -> and -> 3)-Glc-(beta-1 ->. EPS2E1 could significantly increase the production of NO, COX-2, TNF-alpha, IL-1 beta and IL-6 by activating the MAPK and NF-KB pathways on RAW264.7 macrophages. EPS2E1 exhibits the potential to be an immunopotentiator in the near future. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

EPS2E1, an exopolysaccharide isolated from cold-seep bacterium Halomonas sp. 2E1, exhibits immune-enhancing activity by activating MAPK and NF-KB pathways in RAW264.7 macrophages. It contains mannose and glucose, and has the potential to be an immunopotentiator in the future.