黄原胶寡糖对野油菜黄单胞菌的抑菌性能研究

碱性条件下对黄原胶进行氧化降解,透析得到三种黄原胶寡糖（XGO-A,XGO-B和XGO-C）,对产物进行FT-IR表征,GPC法测定其分子量分别为3600、7500和10100。三种黄原胶寡糖的丙酮酸含量分别为5.7%、5.3%和4.8%;还原糖含量分别为23.7%、22.5%和21.1%。采用琼脂平板打孔法、最低抑菌浓度以及生长曲线方法,考察了三种黄原胶寡糖对野油菜黄单胞菌的抑菌能力;同时检测了三种寡糖对野油菜黄单胞菌细胞膜通透性的影响。结果表明,分子量为7500的XGO-B具有更好的抑菌性能。而当丙酮酸和还原糖含量相近时,对野油菜黄单胞菌的抑菌性能可能与黄原胶寡糖的分子量有关;随着分子量的上升,寡糖对野油菜黄单胞菌细胞膜破坏增强,这表明破坏细胞膜通透性是抑菌机理之一。 

Antibacterial activities of Xanthan Oligosaccharides against Xanthomonas campestris

Three xanthan oligosaccharides ( XGO-A, XGO-B and XGO-C) were prepared by oxidative degradation in alkaline condition.The products were characterized by FT- IR, and the molecular weights of the products determined by GPC method were 3600, 7500 and 10100, respectively.The pyruvate acid contents of the three xanthan oligosaccharides were 5.7%, 5.3% and 4.8%, respectively, and reducing sugar contents were 23.7%, 22.5% and 21.1%, respectively.The antibacterial activity of three xanthan oligosaccharides against the X.campestris was investigated by the inhibition zone, minimal inhibitory concentration ( MIC) and the influence on the growth of X. campestris.Effects of xanthan oligosaccharides on electric conductivity of liquid medium of X.campestris were also determined.The results indicated that XGO-B exhibited higher antibacterial activity than XGO-A and XGO-C. It meant that the antibacterial effect of xanthan oligosaccharides may be related to their molecular weight.The effect of xanthan oligosaccharides on the cell membrane permeability of X.campestris became stronger when the molecular weight of xanthan oligosaccharides increased.It indicated that the damage of cell membrane of X.campestris is one of the antibacterial mechanisms to X.campestris.