关键词: 关键词：乳酸乳球菌, 镉胁迫, 电镜, 亚细胞结构

Abstract: Abstract：By scanning electron microscopy (SEM)the cell face and subcellular structure in different contration of Cd were investigated.In the medium containing 0mg/L,10 mg/L, 50 mg/L, 100 mg/L, 200 mg/L Cd2 + Lactococcus lactis cells were observed .The SEM result showed that the PC strain(with no Cd2 +) was spherical and had smooth surface;the long diameter was 960 nm and the short diameter was 775 nm. When the added Cd=50 mg/L, there were many white bulkloads on the surface. The amount of Survival Stains began to fall under 100 mg/L Cd2 + and the white bulkloads aggregated to conglobation and became biolith with 200 mg/L Cd stress. The TEM results showed that PC strain structure was intact and cellular content were well distributed with no Cd2 +; the strain keep well in 10, 50 mg/L ，when exposed to 100 ,200 mg/L Cd2 + it began to change anormaly such as cell lysis and the release of cellular contens from holes in the cell membrance ,in addition , there were piasmolysis and disappear in cell wall and membrance. The total results indicated that the low concentration of Cd2 + (≤50 mg/L) have nearly no effection to PC strain and began to inhibit the normal growth of it when Cd2 + up to 100, 200 mg/L.

Key words: Lactococcus lactis, Cadmium stress, Electric mirror, Subcellular structure