Zhang Zilian, Cai Ruanhong, Zhang Wenhui, Fu Yingnan, Jiao Nianzhi
State Key Laboratory of Marine Environmental Science, Institute of Marine Microbes and Ecospheres, Xiamen University, Xiamen 361102, China.
Mar Drugs. 2017 Jun 12;15(6):175. doi: 10.3390/md15060175.
Most marine bacteria can produce exopolysaccharides (EPS). However, very few structures of EPS produced by marine bacteria have been determined. The characterization of EPS structure is important for the elucidation of their biological functions and ecological roles. In this study, the structure of EPS produced by a marine bacterium, sp. JL2810, was characterized, and the biosorption of the EPS for heavy metals Cu, Ni, and Cr was also investigated. Nuclear magnetic resonance (NMR) analysis indicated that the JL2810 EPS have a novel structure consisting of the repeating unit of [-3)-α-Rha-(1→3)-α-Man-(1→4)-α-3OAc-GalA-(1→]. The biosorption of the EPS for heavy metals was affected by a medium pH; the maximum biosorption capacities for Cu and Ni were 140.8 ± 8.2 mg/g and 226.3 ± 3.3 mg/g at pH 5.0; however, for Cr it was 215.2 ± 5.1 mg/g at pH 5.5. Infrared spectrometry analysis demonstrated that the groups of O-H, C=O, and C-O-C were the main function groups for the adsorption of JL2810 EPS with the heavy metals. The adsorption equilibrium of JL2810 EPS for Ni was further analyzed, and the equilibrium data could be better represented by the Langmuir isotherm model. The novel EPS could be potentially used in industrial applications as a novel bio-resource for the removal of heavy metals.
大多数海洋细菌都能产生胞外多糖（EPS）。然而，由海洋细菌产生的EPS的结构很少被确定。EPS结构的表征对于阐明其生物学功能和生态作用很重要。在本研究中，对一种海洋细菌sp. JL2810产生的EPS的结构进行了表征，并研究了该EPS对重金属铜、镍和铬的生物吸附作用。核磁共振（NMR）分析表明，JL2810 EPS具有一种新颖的结构，其重复单元为[-3)-α-鼠李糖-(1→3)-α-甘露糖-(1→4)-α-3-O-乙酰基-半乳糖醛酸-(1→]。EPS对重金属的生物吸附受培养基pH值的影响；在pH 5.0时，对铜和镍的最大生物吸附容量分别为140.8±8.2 mg/g和226.3±3.3 mg/g；然而，对铬而言，在pH 5.5时为215.2±5.1 mg/g。红外光谱分析表明，O-H、C=O和C-O-C基团是JL2810 EPS吸附重金属的主要官能团。进一步分析了JL2810 EPS对镍的吸附平衡，平衡数据可以更好地用朗缪尔等温线模型表示。这种新型EPS有可能作为一种新型生物资源用于工业应用中去除重金属。
