微量热法研究黄芪多糖对大肠杆菌的抑制功能及机理

摘要

The effects of pH,temperature,ionic strength and Astragalus Polysaccharides (APS)on the growth of Escherichia coli (E.coli)were studied by means of microcalorimetry method.The results show that when pH is lower than 5 or higher 9,metabolism of E.coli growth slows down gradually.The same phenomenon can be observed under different temperature conditions.The addition of NaCl can stimulate the growth rate constant.The low dose of APS can stimulate the growth of E.coli,but the high dose of APS can inhibit E. coli,which can even be completely inhibited.In the presence of APS,the permeability of the cell membrane gradually increased,even cell membrane was damaged.The inhibition zone formed in the presence of APS is about 30 mm,which indicates that it has strong antibacterial function.%通过微量热法研究了 pH、温度、离子强度和黄芪多糖对大肠杆菌生长的影响,探讨了黄芪多糖对大肠杆菌的抑制作用和机理.研究发现：pH 降低到5或升高到9,或升高或降低温度,大肠杆菌的生长代谢逐渐变慢,表现为停滞期增加,进入对数期的时间增加,最大放热功率降低；适量 NaCl(0．1 mol/L)能够刺激生长速率常数急剧上升；低剂量的黄芪多糖能够刺激大肠杆菌的生长,但高剂量的黄芪多糖能够抑制大肠杆菌,甚至能够完全抑制.黄芪多糖的不断加入,导致测量DP H 的荧光偏振度逐渐提高,表明细胞膜通透性在逐渐增加,细胞膜的流动性却在不断降低,说明细胞膜逐步遭到了破坏.黄芪多糖存在下形成的抑菌圈为30 mm左右,表明具有较强的抑菌功能.