Xu Linxiang, Wu Dan, Xu Haiyang, Zhao Ziyan, Chen Qianqian, Li Hanqi, Wei Zhen, Chen Li
Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, 59 Cangwu Road, Haizhou, Lianyungang 222005, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, 59 Cangwu Road, Lianyungang 222005, China; Jiangsu Institute of Marine Resources Development, 59 Cangwu Road, Haizhou, Lianyungang 222005, China; School of Food Science and Engineering, South China University of Technology, Guangzhou, China.
Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, 59 Cangwu Road, Haizhou, Lianyungang 222005, China.
Int J Biol Macromol. 2023 Oct 1;250:126330. doi: 10.1016/j.ijbiomac.2023.126330. Epub 2023 Aug 12.
Levan is a high-valued β-(2,6)-linked fructan with promising physicochemical and physiological properties and has diverse potential applications in the food, nutraceutical, pharmaceutical and cosmetic industry, but its commercial availability is still restricted to the relatively high costs of production. In this study, a strain identified as Microbacterium sp. XL1 was isolated from soil and highly produced exopolysaccharide (EPS). HPLC, FTIR and NMR spectroscopy revealed XL1-EPS is a levan-type fructan connected by β-(2, 6) linkages. SEM, DLS and TGA-DSC analysis showed that XL1-EPS processed high morphological versatility, narrow size distribution in its solutions and excellent thermal stability. The levan yield reached 83.67 ± 4.06 g/L with corresponding productivity of 3.49 ± 0.17 g/L/h and a conversion yield of 39.8 ± 1.9 % using sucrose (210 g/L) as substrates under the optimal cultivation conditions concluded by the response surface methodology (RSM). More strikingly, the XL1 strain also has multi-type fructanases to generate levanbiose, kestose, DFA IV and other L-FOSs. These results suggest Microbacterium sp. XL1 is a promising strain to produce levan and can provide various levan/inulin-degrading enzymes to create a great diversity of FOSs.
左聚糖是一种具有良好物理化学和生理特性的高价值β-(2,6)-连接的果聚糖，在食品、营养保健品、制药和化妆品行业有多种潜在应用，但其商业可得性仍受限于相对较高的生产成本。在本研究中，从土壤中分离出一株鉴定为微小杆菌属XL1的菌株，该菌株能高产胞外多糖（EPS）。高效液相色谱、傅里叶变换红外光谱和核磁共振光谱显示，XL1-EPS是一种通过β-(2,6)键连接的左聚糖型果聚糖。扫描电子显微镜、动态光散射和热重-差示扫描量热分析表明，XL1-EPS具有高度的形态多样性、溶液中窄的粒径分布和优异的热稳定性。在响应面法（RSM）得出的最佳培养条件下，以蔗糖（210 g/L）为底物时，左聚糖产量达到83.67±4.06 g/L，相应生产力为3.49±0.17 g/L/h，转化率为39.8±1.9%。更引人注目的是，XL1菌株还具有多种类型的果聚糖酶，可生成左糖二糖、蔗果三糖、四糖型蔗果低聚糖和其他低聚果糖。这些结果表明，微小杆菌属XL1是一种有潜力生产左聚糖的菌株，并且可以提供各种左聚糖/菊粉降解酶以产生多种多样的低聚果糖。
