钠型结冷胶与乳酸链球菌素的接枝条件优化

Optimization of grafting conditions between sodium type gellan and nisin

以1-乙基-(3-二甲基氨基丙基)碳二亚胺盐酸盐和N-羟基硫代琥珀酰亚胺钠盐为交联剂,对乳酸链球菌素接枝钠型结冷胶的反应条件进行单因素法优化,并利用傅里叶变换红外光谱和抑菌时效性实验对接枝物进行表征。结果表明,乳酸链球菌素与钠型结冷胶的最佳接枝反应条件为:1-乙基-(3-二甲基氨基丙基)碳二亚胺盐酸盐和N-羟基硫代琥珀酰亚胺钠盐的摩尔比为2∶1、反应体系pH为6、反应体系温度为40℃、钠型结冷胶的活化时间为70 min、加入乳酸链球菌素后的反应时间为16 h。接枝率由纯化前的不足5.0%提升至14.5%,弱碱性条件下对枯草芽孢杆菌的抑菌时效性也由12 h延长至24 h。

The antibacterial activity of nisin under weak alkali conditions can be reinforced by modification with sodium type gellan.Single factor method is used to optimize reaction conditions for the grafting reaction between nisin and sodium-type gellan with 1-ethyl-（3-dimethyl aminopropyl） carbodiimine hydrochloride（EDC HCl） and Nhydroxysulfosuccinimide sodium salt（NHSS） as crosslinking agents.Fourier transform infrared spectroscopy（FT-IR）and antibacterial timeliness tests are utilized to characterize the grafted copolymer.According to results,the optimal conditions for the grating reaction are as follows：the molar ratio of EDC HCl to NHSS is 2∶1,pH value is 6 for the reaction system,reaction temperature is at 40℃,activation time for gellan is 70 min and the reaction time is 16 h after nisin is added.The graft ratio of the copolymer under the optimal conditions achieves 14.5%,which is much higher than the less 5.0% under non-optimized conditions.The antibacterial timeliness of the graft copolymer against Bacillus subtilis increases 24 h under weak alkaline conditions,compared with the 12 h before optimization.