Extracellular Polysaccharides Produced By Four Microorganisms From Different Environments

Microbial resources are increasingly attracted researchers’ attention. Microorganisms which survived in the ocean, high saline and other special environmentent could produce extracellular polysaccharides with unique structures and various activities. In this paper, the extracellular polysaccharides were obtained from the fermented broth of four different microorganisms using column chromatography. The physicochemical properties, antioxidant activities and structural characterizations of the extracellular polysaccharides were investigated by a variety of chemical methods and modern analytical technologies. The results are as follows:The extracellular polysaccharide TW from the fermented broth of the mangrove mud derived actinomycete THS-55 was isolated, and purified by Q Sepharose Fast Flow anion exchange chromatography. Two polysaccharides TWB and TWA were obtained. TWB was further purified by Sephacryl S-100 gel chromatography to give the pure product TWB-A. High performance gel permeation chromatography (HPGPC) and PMP pre-column derivatization HPLC (PMP-HPLC) analyses showed that the molecular weight of TWB-A was about 30.8 kDa. TWB-A mainly consisted of Glc and Man in a molar ratio of 13.67:1. Based on the methylation analysis and nuclear magnetic resonance spectroscopy, the main chain of TWB-A was characterized to mainly consist of â†'3)Glcp(1â†', with additional branches at C-4 consisting of Glcp(1â†' residues. The antioxidant activity of TWB-A was evaluated with the scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide and hydroxyl radicals in vitro, and the results indicated that TWB-A had a high antioxidant activity, especially scavenging ability on DPPH radicals. The EC50 values of TWB-A for superoxide, DPPH and hydroxyl radicals were 4.89 mg/mL,1.79 mg/mL and 6.21 mg/mL, respectively. The results showed that TWB-A was a novel extracellular polysaccharide with antioxidant activity. Marine actinomycete is an abundant source of bioactive extracellular polysaccharides.The extracellular polysaccharide HS from the fermented broth of Binzhou saline plant endophytic fungus SXH-69 was isolated, and purified by Q Sepharose Fast Flow anion-exchange chromatography and Sephacryl S-100 gel-permeation chromatography. Two extracellular polysaccharides HSA-M and HSC-N were obtained. HPGPC analysis showed that the molecular weights of HSA-M and HSC-N were 13.5 kDa and 18.3 kDa, respectively. PMP-HPLC analysis showed that HSA-M mainly contained Man, GlcN, Glc and Gal in a molar ratio of 2.21:0.20:0.68:1.00. HSC-N was mainly composed of Man, Glc and Gal with a molar ratio of 5.06:0.31:1.00. IR and methylation analyses indicated that HSA-M mainly consisted of â†'4)Man(1â†',â†'2)Gal(1â†',â†'6)Glc(1â†' andâ†'6)Man(1â†', with small amounts of Glc(1â†'. terminal Man and â†'2,4)Man(1â†'. HSC-A was mainly composed of â†'4)Man(1â†',â†'6)Man(1â†',â†'2,6)Gal(1â†'and â†'>2,4)Man(1â†', with minor amounts of Man(1â†' and â†'2)Glc(1â†'. The results of in vitro antioxidant activity showed that HSA-M had better scavenging abilities of DPPH and hydroxyl radicals. The EC50 values of HSA-M for superoxide anion, DPPH and hydroxyl radicals were 8.17 mg/mL,1.87 mg/mL and 2.98 mg/mL, respectively.The crude extracellular polysaccharide ZD from the fermented broth of Jiaozhou Bay algae symbiotic fungus 2S-2 was isolated, and purified by Q Sepharose Fast Flow anion-exchange chromatography and Sephacryl S-100 gel-permeation chromatography. Two extracellular polysaccharides ZDA-M and ZDB-N were obtained. HPGPC analysis showed that the molecular weights of ZDA-M and ZDB-N were 3.65 kDa and 3.75 kDa, respectively. PMP-HPLC analysis showed that ZDA-M and ZDB-N mainly consisted of Man and Glc, and the molar ratios were 1:21.9 and 1:28.3, respectively. Based on the methylation analysis, the main chain of ZDA-M was characterized to be composed of â†'4)Glc(1â†', terminal Glc,â†'6)Glc(1â†'and â†'2,4)Glc(1â†'. The results of in vitro antioxidant activity showed that ZDA-M exhibited better scavenging activity of DPPH radicals. The EC50 values of ZDA-M for DPPH and hydroxyl radicals were 2.89 mg/mL and 7.54mg/mL, respectively.The crude extracellular polysaccharide ZY from the fermented broth of Xisha sponge-derived fungus Paraphaeosphaeriasp ZXM-5 was isolated, and purified by Q Sepharose Fast Flow anion-exchange chromatography and Sephacryl S-100 gel-permeation chromatography. An extracellular polysaccharide ZYB-A was obtained, its yield was 0.37g/L. HPGPC analysis showed that the molecular weight of ZYB-A was about 16.3 kDa. PMP-HPLC analysis indicated that ZYB-A mainly consisted of Man, Glc and Gal in a molar ratio of 7.71:0.76:1.78. Methylation analysis showed that ZYB-A are mainly composed of terminated Man, â†'3)Gal(1â†', â†'3)Man(1â†' andâ†'3,4)Man(1â†' with a small amount of â†'6)Glc(1â†'.The investigation provided novel marine extracellular polysaccharides for the "marine polysaccharides library", lay important foundation for further research and development of extracellular polysaccharides from marine microorganisms.