黄原胶寡糖琥珀酸酯衍生物的制备及其对野油菜黄单胞菌的抑菌性能研究

将碱性条件下制备的黄原胶寡糖与琥珀酸酐进行反应,得到三种不同取代度的黄原胶寡糖琥珀酸酯衍生物（SA-XG-1、SA-XG-2、SA-XG-3）,凝胶渗透色谱（GPC）法测定产物分子量分别为7560、6400和7430u。三种衍生物的取代度分别为0.18、0.32和0.43。采用琼脂平板打孔法、最低抑菌浓度以及生长曲线法,考察了三种衍生物对野油菜黄单胞菌的抑菌能力;检测了三种衍生物对野油菜黄单胞菌细胞膜通透性影响。结果表明,随取代度的上升,抑菌圈缩小,最小抑菌浓度升高,对野油菜黄单胞菌细胞膜破坏能力减弱。当分子量相仿、丙酮酸和还原糖含量相近时,衍生物的抑菌性能可能与其取代度有关;但取代度上升,衍生物对野油菜黄单胞菌细胞膜破坏减弱,表明破坏细胞膜通透性是抑菌主要机理之一。 

Preparation of succinyl xanthan oligosaccharides and its antibacterial activities against Xanthomonas campestris

Three succinyl xanthan oligosaccharides with different substituting degrees (SA-XG-1, SA-XG-2 and SA-XG-3) were prepared. Their molecular weights determined by GPC method were 7560, 6400 and 7430 u, respectively. Their substituting degree was 0.18, 0.32 and 0.43, respectively. The antibacterial activities of three succinyl xanthan oligosaccharides against Xanthomonas campestris (X. campestris) were investigated by the inhibition zone, minimal inhibitory concentration (MIC) and the influence on the growth of X. campestris. The influence of three succinyl xanthan oligosaccharides on electric conductivity of X. campestris was also determined. The results showed that the inhibition zone was decreased, the MIC was increased, but the damage capability to cell membrane of X. campestris was decreased with the increasing of the substituting degrees, in other words, the SA-XG-1 possessed the best antibacterial activity. The results showed that the antibacterial activity of succinyl xanthan oligosaccharides may be related to the substituting degrees, and the damage capability to cell membrane of X. campestris may be the one of the main antibacterial mechanism of succinyl xanthan oligosaccharides.