Microalgae as photosynthetic microorganisms are the source of valuable compounds such as proteins, carotenoids, lipids and carbohydrate polymers. Among the different phyla, Porphyridium as part of the red microalgae (Rhodophyta) are of high importance as producers of sulfated polysaccharides. As the name suggests these microalgae are typically red; however, Porphyridium sordidum has an olive-green color and was recently described as a putative exopolysaccharide producer. Exopolysaccharides (EPS) are sugars polymers excrete to the culture medium. In this study P. sordidum is evaluated for the first time in detail as newly described EPS producer in direct comparison to the already characterized EPS producer Porphyridium purpureum. The evaluation was performed on several aspects, such as morphological differences between the two strains followed by the comparison of the growth behavior, nitrate and phosphate uptake during cultivation of both strains, and a detailed analysis of the EPS. P. purpureum consumed 51 ± 4.6% of nitrate and 95 ± 2.1% of phosphate compared to P. sordidum which utilized 17 ± 0.1% of nitrate and 68 ± 0.1% of phosphate at day 30 of cultivation. The produced EPS were analyzed and revealed the major constitutional carbohydrate monomers of the EPS to be xylose, galactose, glucose and glucuronic acid. In addition, other substituents that decorate the EPS were identified as sulfate and methyl groups. Finally, rheological measurements (viscosity curves and amplitude sweeps) were performed to analyze the physicochemical properties.

微藻作为光合微生物是有价值的化合物的来源，例如蛋白质，类胡萝卜素，脂质和碳水化合物聚合物。在这些不同的门类，紫球作为红色微藻（红藻门）的一部分是具有高重要性作为硫酸化多糖的生产者。顾名思义，这些微藻通常是红色的。然而，Sorphydium sordidum具有橄榄绿色，最近被描述为推定的胞外多糖生产商。胞外多糖（EPS）是分泌到培养基中的糖类聚合物。在这项研究中P. sordidum是用于详细首次评价为新近被描述的EPS生产者在直接比较中已经表征EPS生产者紫草。在几个方面进行了评估，例如两个菌株之间的形态差异，然后比较了两个菌株的生长行为，两个菌株在培养过程中硝酸盐和磷酸盐的吸收以及对EPS的详细分析。象草相比消耗硝酸盐的51±4.6％和磷酸的95±2.1％P. sordidum在培养的第30天使用了17±0.1％的硝酸盐和68±0.1％的磷酸盐。分析产生的EPS，发现EPS的主要构成碳水化合物单体是木糖，半乳糖，葡萄糖和葡糖醛酸。此外，装饰EPS的其他取代基被鉴定为硫酸根和甲基。最后，进行流变学测量（粘度曲线和振幅扫描）以分析理化性质。