Structural Characterizations Of The Extracellular Polysaccharides Produced By3Marine Microorganisms

Marine contains abundant microbe resources. The marine microorganisms oftenproduce various extracellular polysaccharides with novel activities due to their specialliving environments. In the paper, the chemical compositions and structuralcharacterizations of the extracellular polysaccharides isolated from the fermentedbroth of three different marine microorganisms were investigated. The research resultsare as follows:1Crude extracellular polysaccharide LD was isolated from the fermented brothof sea mud actinomycetes streptomyces sp., and purified by Q-Sepharose Fast Flowcolumn and Sephacryl S-100column. The purified extracellular polysaccharide,designated LDS2, was obtained. Monosaccharide composition analysis byreversed-phase HPLC showed that LDS2was a mannan with only Man. LDS2appeared as symmetrical sharp peak in the HPGPC chromarogram, indicating itshomogenity. The molecular weight of LDS2was21kDa. The results of IR spectra andmethylation analysis demonstrated that LDS2mainly consisted of three kinds oflinkage type units, including�'2)Manp(1�',�'6)Manp(1�'and�'2,6)Manp(1�'.The results indicated that LDS2was an extracellular polysaccharide with highbranched chain structures.2Crude extracellular polysaccharide BB was isolated from the fermented brothof sea mud actinomycetes streptomyces sp., and purified by Q-Sepharose Fast Flowcolumn and Sephacryl S-100column. The two purified extracellular polysaccharides,designated BBW2-1and BBS2-1, were obtained. Monosaccharide compositionanalysis by reversed-phase HPLC showed that BBW2-1contained Man and Glc withmolar ratio of1.0:15.4, and BBS2-1also contains Man and Glc with the molar ratio of1.0:11.8. BBW2-1and BBS2-1consisted of high proportion of Glc. BBW2-1andBBS2-1appeared as symmetrical sharp peaks in the HPGPC chromarograms,indicating their homogenities.The molecular weights of BBW2-1and BBS2-1were 6.2kDa and6.1kDa, respectively. The results of IR spectra and methylation analysisdemonstrated that BBW2-1and BBS2-1mainly consisted of�'4)Glcp(1�'and�'6)Glcp(1�', and also contained high ratio of�'4,6)Glcp(1�'residues. Thus,BBW2-1and BBS2-1had high amount of branched chains. In addition, smallamounts of�'2)Glcp(1�'and�'4)Manp(1�'were also found in BBS2-1.3Crude extracellular polysaccharide HB was isolated from the fermented brothof mangrove root fungus Aspergillus sp., and purified by Q-Sepharose Fast Flowcolumn and Sephacryl S-100column. The four purified polysaccharide, designatedHBW2-2, HBW2-3, HBS1and HBS2, were obtained. Monosaccharide compositionanalysis by reversed–phase HPLC showed that HBW2-2and HBW2-3mainlycontained Man and Gal, with small amount of GalNAc and minor amounts of GlcNand Glc. Both of HBS1and HBS2were mainly composed of Man. Besides, HBS1contained a small amount of GalNAc，and HBS2contained a small amount of Galwith a minor amount of Glc. HPGPC analyses showed that HBW2-2, HBW2-3, HBS1and HBS2all appeared as symmetrical sharp peaks in the HPGPC chromatograms,indicating their homogeneities.The molecular weights of HBW2-2, HBW2-3, HBS1and HBS2were12.5,7.1,34.1,9.4kDa, respectively. The results of IR andmethylation analyses demonstrated that HBW2-2mainly contained four kinds oflinkage type units�'4)Galp(1�',�'3)Manp(1�',�'2)Manp(1�'and�'2,6)Manp(1�', indicating the presence of branched chain. HBW2-3mainlyconsisted of�'4)Galp(1�',�'2)Manp(1�',�'6)Manp(1�',�'2,6)Manp(1�',suggesting the presence of the branched chain. Particularly, both of HBW2-2andHBW2-3had the Galf(1�'units. HBS1contained the similar proportions of linkagetype units�'2)Manp(1�',�'4)Manp(1�',�'6)Manp(1�', and large amount of�'2,6)Manp(1�', indicating the presence of the high branched chain. HBS2containedsimilar proportions of linkage type units�'4)Galp(1�',�'2)Manp(1�',�'6)Manp(1�', and several amounts of�'2,6)Manp(1�'and�'2,3)Manp(1�', andthe result suggested that HBS2had the presence of the high levels of branched chains.The same as HBW2-2and HBW2-3, HBS2also had Galf(1�'units.The results provided novel marine polysaccharides for the “marine polysaccharides database” and established the basis for further development ofextracellular polysaccharide products from marine microorganism.