五株双歧杆菌胞外多糖功能特性的差异分析

Differential analysis of functional properties of exopolysaccharides from five strains of Bifidobacterium

该研究旨在分析比较5株双歧杆菌(假小链双歧杆菌BP-1、长双歧杆菌BL-3、动物双歧杆菌BA-5、动物双歧杆菌BA-6和婴儿双歧杆菌BI-38)胞外多糖(exopolysaccharides,EPS)理化性质的差异。通过水提醇沉法提取了5株双歧杆菌的EPS,分析比较了其抗氧化活性、抑菌特性、表观形态、官能团种类和流变特性等。结果表明,BA-5的产量为(552.69±3.38)mg/L,显著高于其他菌株(P<0.05);体外抗氧化试验结果表明,5种EPS对DPPH自由基和羟自由基均具有较强的清除能力,其中BA-6 EPS对超氧阴离子自由基的清除率达到(67.78±0.68)%,显著高于其他EPS。抑菌试验结果发现,5种EPS对大肠杆菌、金黄色葡萄球菌和单增李斯特菌均有抑菌活性,其中BA-6 EPS对单增李斯特菌抑菌率高达(94.96±1.43)%。扫描电子显微镜(scanning electron microscope,SEM)观察发现5种EPS的表观形态存在差异,傅里叶中远变换红外光谱(Fourier middle far transform infrared spectroscopy,FT-IR)图谱分析发现5种EPS官能团的种类没有明显差异。流变学结果表明,EPS溶液的表观黏度随着剪切速率的增加呈现下降趋势,表现出典型的剪切变稀的非牛顿流体特征,且BA-6 EPS比其他4种EPS拥有更高的初始表观黏度。差示扫描量热仪(differential scanning calorimetry,DSC)测定结果表明5种EPS具有较高的热稳定性。这些结果表明,不同来源和种类的双歧杆菌EPS在功能特性方面具有差异,并且动物双歧杆菌BA-6各项功能特性比较优良,具有较高的潜在应用价值。

The aim of this study is to analyze and compare the physical and chemical properties of exopolysaccharides from five strains of Bifidobacterium(Bifidobacterium pseudocatenulatum BP-1,Bifidobacterium longum BL-3,Bifidobacterium animalis BA-5,Bifidobacte-rium animalis BA-6,and Bifidobacterium infantis BI-38).The exopolysaccharides from five strains of Bifidobacterium were extracted by water extraction and alcohol precipitation,and their antioxidant activity,antibacterial properties,apparent morphology,functional group types and rheological properties were analyzed and compared.The results showed that the yield of BA-5 was(552.69±3.38)mg/L,which was significantly higher than that of the other strains(P<0.05);In vitro antioxidant tests results showed that the five exopolysac-charides exhibited strong scavenging ability on both DPPH radical and hydroxyl radical.Among these,the scavenging rate of BA-6 exopo-lysaccharides to superoxide anion radical reached(67.78±0.68)%,which was significantly higher than that of other exopolysacchar-ides.The results of the antibacterial test showed that all of the five exopolysaccharides had antibacterial activities against Escherichia coli,Staphylococcus aureus and Listeria monocytogenes,of which BA-6 exopolysaccharides had a highest bacteriostatic rate of(94.96±1.43)%against L.monocytogenes.There were differences among the apparent morphologies of the five exopolysaccharides under scanning electron microscope,and there were no differences among types of functional groups in exopolysaccharides with Fourier middle far trans-form infrared spectroscopy.The apparent viscosity of exopolysaccharides solution decreased with the increase of shear rate,typical shear thinning non-Newtonian fluid characteristics was certified,and BA-6 exopolysaccharides had higher initial apparent viscosity than the oth-ers.Differential scanning calorimetry results indicated that all five exopolysaccharides showed higher thermal stability.These results showed that the functional properties of Bifidobacterium exopolysaccharides from different sources and species were different,and those of B.animalis BA-6 was better and had higher potential value for application.