School of Food and Biological Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang 212013, Jiangsu, PR China.
School of Materials Science and Engineering, Dalian Jiaotong University, Huanghe Road 794, Dalian 116028, Liaoning, PR China.
Int J Biol Macromol. 2024 Nov;279(Pt 2):135225. doi: 10.1016/j.ijbiomac.2024.135225. Epub 2024 Aug 30.
The production conditions of exopolysaccharide (EPS) from Leuconostoc mesenteroides XR1 were optimized by response surface methodology (RSM). Maximum EPS yield was 56.59 ± 0.51 g/L under fermentation conditions with 2.6 g/L ammonium citrate, initial pH 6.5 and temperature 23 °C, which was 6.21-fold greater than the EPS yield before optimization. Characterization of the chain conformation using Congo red test and circular dichroism (CD) showed that EPS exhibited a random coil structure in aqueous solution. The CD results revealed that the EPS concentration altered its hydrogen-bond interactions and chirality, but did not change its chain conformation. The average polydispersity index (PDI) of the EPS solution was only 27.16 %, indicating that it was uniformly distributed in the aqueous solution with high stability. The degradation temperature of EPS was 253.11 °C, indicating high thermal stability. EPS possessed the ability to scavenge activities of free radicals and was protective against oxidative stress-induced plasmid DNA damage. In addition, stable hydrogels could be formed at EPS concentrations above 5 % (w/v). These results collectively showed that EPS can be used commercially as an antioxidant and drug delivery carrier.
响应面法优化肠膜明串珠菌 XR1 胞外多糖（EPS）的生产条件。在发酵条件为 2.6 g/L 柠檬酸铵、初始 pH 值 6.5 和温度 23°C 时，EPS 的最大产量为 56.59±0.51 g/L，比优化前的 EPS 产量提高了 6.21 倍。刚果红试验和圆二色性（CD）分析表明，EPS 在水溶液中呈现无规卷曲构象。CD 结果表明，EPS 浓度改变了其氢键相互作用和手性，但不改变其链构象。EPS 溶液的平均多分散指数（PDI）仅为 27.16%，表明其在水溶液中分布均匀，具有高稳定性。EPS 的降解温度为 253.11°C，表明其具有较高的热稳定性。EPS 具有清除自由基活性的能力，能够保护氧化应激诱导的质粒 DNA 损伤。此外，当 EPS 浓度高于 5%（w/v）时，可以形成稳定的水凝胶。这些结果表明，EPS 可以作为一种抗氧化剂和药物载体在商业上应用。
