Process Biochemistry ( IF 4.4 ) Pub Date : 2021-08-26 , DOI: 10.1016/j.procbio.2021.08.021 Younus Mohd Tilwani 1 , Avinash Kant Lakra 1 , Latha Domdi 1 , Sumedha Yadav 1 , Natwar Jha 1 , Venkatesan Arul 1
In the present study, Enterococcus faecium MC-5 isolated from the fish gut was cultured in the MRS broth to produce exopolysaccharide (EPS). The maximum EPS production was optimized using Response Surface Methodology (RSM) with three different factors which include sucrose, ammonium nitrate and pH. RSM result predicted that maximum EPS (16.48 g/L) production could be attained by supplementing 30 g/L sucrose and 15 g/L ammonium nitrate in the MRS broth with the initial pH of 6.407. The EPS produced was subjected to purification by column chromatography techniques. Monosaccharide analysis by HPLC confirmed the presence of fructose monomer. The purified EPS MC-5 showed a molecular weight of 24 kDa. The purified EPS was further characterized by FT-IR and NMR which confirmed the presence of β-(2,6) fructofuranoside units and suggested that the EPS MC-5 is a levan-type polysaccharide. Congo red analysis suggested that the EPS MC-5 possesses a triple-helix structure whereas the SEM images showed that the EPS has a porous and globular structure. The EPS was found to be semi-crystalline through XRD analysis. Thermogravimetric analysis showed EPS MC-5 possesses higher thermal stability having a degradation temperature of 338.13 °C. The EPS MC-5 exhibited excellent antioxidant activities and showed promising antibiofilm activity against Listeria monocytogenes, Salmonella enterica, Salmonella typhi and Vibrio anguillarum. The present study is the first report of levan-type EPS production by Enterococcus faecium sp., which has been characterized for its physicochemical and biological properties. These properties associated with EPS MC-5 suggested that it can serve as a potential ingredient or supplement in the food system with significant health benefits.
中文翻译:
具有潜在生物活性的屎肠球菌MC-5低分子果聚糖的优化和理化表征
在本研究中,粪肠球菌从鱼肠中分离出的 MC-5 在 MRS 肉汤中培养以产生胞外多糖 (EPS)。使用响应面方法 (RSM) 和三个不同的因素(包括蔗糖、硝酸铵和 pH 值)对最大 EPS 产量进行了优化。RSM 结果预测,通过在初始 pH 值为 6.407 的 MRS 肉汤中补充 30 g/L 蔗糖和 15 g/L 硝酸铵,可以获得最大的 EPS (16.48 g/L) 产量。产生的EPS通过柱层析技术进行纯化。HPLC 的单糖分析证实了果糖单体的存在。纯化的 EPS MC-5 的分子量为 24 kDa。纯化的 EPS 通过 FT-IR 和 NMR 进一步表征,证实了 β-(2,6) 呋喃果糖苷单元的存在,并表明 EPS MC-5 是一种左聚糖型多糖。刚果红分析表明 EPS MC-5 具有三螺旋结构,而 SEM 图像显示 EPS 具有多孔和球状结构。通过XRD分析发现EPS是半结晶的。热重分析表明,EPS MC-5 具有更高的热稳定性,降解温度为 338.13 °C。EPS MC-5 表现出优异的抗氧化活性,并显示出有希望的抗生物膜活性单核细胞增生李斯特菌、肠沙门氏菌、伤寒沙门氏菌和鳗鲡弧菌。本研究是屎肠球菌生产果聚糖型 EPS 的第一份报告,其理化和生物学特性已得到表征。EPS MC-5 的这些特性表明它可以作为食品系统中的潜在成分或补充剂,具有显着的健康益处。