Effects of different concentrations of NaNO2 on the degradation ability,nitrite reductase (NiR) activity and cell surface properties of Lactobacillus plantarum (Lp) FQR were investigated,and the cell morphology of which was observed by electron microscope.The results showed that the degradation ability and NiR activity of FQR was decreasing with the increase of NaNO2 concentrations within 0-0.150％.Under the condition of 0.045％ NaN02,FQR could efficiently degrade NaNO2 within 16 h with (94.85 ± 2.96)％ of degradation rate and (174.60 ± 13.67) U/104 of NiR activity.In addition,high concentrations of NaN02 could also contribute to the significant increase of cell surface hydrophobicity and membrane permeability.There were no differences in cell surface morphology of FQR between the nitrite-free group and 0.045％ NaNO2 group,whereas the surface of FQR exposed to 0.120％ NaNO2 appeared depression and wrinkle by observation through scanning electron microscope.FQR in nitrite-free group exhibited numerous energy storage granules,number of which decreased obviously with increasing concentration of NaNO2.The intracellular energy storage material almost disappeared,and external flow of cytoplasm was observed through transmission electron microscope when FQR exposed to 0.120％ NaNO2.In summary,high concentrations of NaNO2 can cause changes in the surface morphology and internal structure of bacteria obviously.%研究不同NaN02浓度对植物乳杆菌(Lp) FQR降解NaNO2能力、亚硝酸盐还原酶(NiR)活性以及细胞表面特性的影响,并经电镜观察细胞形态.结果表明,在0～0.150％ NaN02范围内,随着浓度的增大,FQR降解能力以及NiR活性均呈下降趋势,在0.045％ NaN02条件下,FQR能够高效降解NaN02,16h降解率达(94.85±2.96)％,NiR活力(174.60±13.67) U/104细胞,而高浓度NaNO2会引起细胞表面疏水性和膜通透性发生显著升高.扫描电镜观察发现,0.045％ NaNO2条件下FQR表面形态与对照组相比未发现明显变化,但0.120％NaNO2时菌体表面出现褶皱和凹陷.透射电镜观察发现,对照组中FQR存在大量储能颗粒,随着NaNO2浓度增大,颗粒物数量明显下降;在0.120％ NaNO2时胞内储能物质几乎消失,并出现细胞质空化现象.高浓度NaN02会引起菌体表面形态和内部结构发生明显变化.
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