Abstract:The effects of different stress systems on the biofilm formation and protease-producing activity of Lactobacillus plantarum zwq9 were analyzed by microplate semi-quantitative method.The results showed that the biofilm of L.plantarum zwq9 was significantly destroyed by proteinase K，while no significant change was found in that treated with sodium periodate.Under lactic acid stress，the growth and biofilm formation of L.plantarum zwq9 were significantly inhibited（P＜0.05）when the concentration of lactic acid reached above 0.8%，and the protease-producing activity of L.plantarum zwq9 was also reduced by more than 90%（P＜0.05）.Under culture temperature stress，the biofilm formation and protease-producing activity of L.plantarum zwq9 at 30℃-40 ℃ were significantly higher than those of other groups（P＜0.05）.Under salt stress，NaCl at lower concentrations（1%-4%）had no significant effect on the biofilm formation of L.plantarum zwq9（P＞0.05），but significantly enhanced its protease-producing activity （P＜0.05）.When the concentration of NaCl was higher than 8%，the biofilm formation and protease-producing activities of L.plantarum zwq9 both decreased by more than 90%.The correlation analysis indicated that the biofilm formation and protease-producing activity of L.plantarum zwq9 had a significant positive correlation（P＜0.01）under the stress conditions of lactic acid and salt.