Department of Biotechnology, School of Life Sciences, Pondicherry University, Puducherry 605014, India.
Department of Biotechnology, School of Life Sciences, Pondicherry University, Puducherry 605014, India.
Int J Biol Macromol. 2020 Jan 15;143:797-805. doi: 10.1016/j.ijbiomac.2019.09.139. Epub 2019 Nov 9.
The present study focused on production, optimization and characterization of exopolysaccharide (EPS) from Weissella confusa MD1. The purified EPS MD1 was also evaluated for in vitro biological activities. The maximum yield of EPS (10.07 ± 0.32 g/L) was obtained with optimized culture conditions of 35 °C at pH 6.5 for 36 h with 4% (w/v) galactose and 1% (w/v) ammonium nitrate supplemented in MRS broth. The crude EPS was purified with diethylamino ethanol-Sepharose Fast Flow column and Sephadex-G 75 column. The physicochemical and functional characterization of the EPS was done by high-performance thin-layer chromatography (HPTLC), high-performance gel permeation chromatography (HPGPC), fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), thermo gravimetric and differential scanning calorimetric (TG-DSC) analysis, x-ray diffraction (XRD) and scanning electron microscopy (SEM). HPGPC analysis showed molecular weight of purified EPS MD1 as 2.909 KDa. Monosaccharide analysis showed that EPS was a novel mannan with mannose as the only monomeric unit present, suggesting EPS to be a homopolysaccharide containing → 6) α-Man p (1 → linkages. Microstructure studies by SEM showed MD1 EPS has globular and porous structure. The purified EPS MD1 exhibited higher thermal stability having degradation temperature around 267.74 °C with melting enthalpy value (Δ H) of 337.7 J/g. The EPS showed promising antioxidant activities with excellent antibiofilm activity against Staphylococcus aureus, Listeria monocytogenes, Salmonella enterica and Salmonella typhi. These striking physicochemical characteristics features and bioactivities of EPS would serve as potential candidate in food processing industry to be used as food adjunct in foods with health benefits. This is the first study reporting a mannan homopolysaccharide from Weissella sp. to be structurally characterized.
本研究聚焦于从魏斯氏菌（Weissella confusa MD1）中生产、优化和表征胞外多糖（EPS）。还评估了纯化的 EPS MD1 的体外生物活性。在 MRS 肉汤中添加 4%（w/v）半乳糖和 1%（w/v）硝酸铵，在 35°C 和 pH 6.5 下优化培养 36 小时，可获得最大 EPS 产量（10.07±0.32 g/L）。粗 EPS 用二乙氨基乙醇-琼脂糖快速流动柱和 Sephadex-G 75 柱纯化。通过高效薄层层析（HPTLC）、高效凝胶渗透色谱（HPGPC）、傅里叶变换红外（FTIR）光谱、核磁共振（NMR）、热重和差示扫描量热（TG-DSC）分析、X 射线衍射（XRD）和扫描电子显微镜（SEM）对 EPS 的理化和功能特性进行了表征。HPGPC 分析表明，纯化的 EPS MD1 的分子量为 2.909 kDa。单糖分析表明，EPS 是一种新型甘露聚糖，仅由甘露糖作为单体单元组成，表明 EPS 是一种含有→6）α-Man p（1→键的均多糖。SEM 的微观结构研究表明，MD1 EPS 具有球形和多孔结构。纯化的 EPS MD1 表现出较高的热稳定性，降解温度约为 267.74°C，熔融焓值（ΔH）为 337.7 J/g。EPS 表现出有前景的抗氧化活性，对金黄色葡萄球菌、单核细胞增生李斯特菌、肠炎沙门氏菌和伤寒沙门氏菌具有优异的抗生物膜活性。这些引人注目的理化特性和生物活性使 EPS 成为食品加工业的潜在候选物，可作为具有健康益处的食品中的食品添加剂。这是首次报道从魏斯氏菌属中分离出甘露聚糖均多糖并对其进行结构表征的研究。
