Abstract: In this study, 70% ethanol extract from the bulbs of Allium macrostemon Bunge was tested for its antibacterial activities against five common microbes. Meanwhile, the stability of its inhibitory effects on E. coli, Aspergillus niger and Saccharomyces cerevisiae was explored. The results showed that the extract sequentially inhibited five common microbes in the following order: E. coli ＞ S. aureus ＞ Penicillium ＞ Saccharomyces cerevisiae ＞ Aspergillus niger. Stability experiments revealed that temperature and pH had strong influence on the antibacterial effect of the extract. The extract exhibited the strongest inhibitory activity at a temperature ranging between 50 ℃ and 60 ℃, which became lower when the temperature was higher than 100 ℃. In addition, the antibacterial activity of the extract was strong under neutral, slightly acidic and slightly alkaline conditions, and decreased with decreasing acidic pH or increasing alkaline pH, and was little affected by UV light illumination and K+, but was affected obviously by some divalent cations such as Mg2+, Ca2+ and Zn2+ as well as Fe3+ as a tervalent cation which had larger effect than these divalent cations.

Key words: Allium macrostemon Bunge, ethanol extract, bacteriostatic property