Application Tetrahymena thermophila for Assessment Biotoxicity of Sodium Benzoate

Abstract:

For investigation the application of protozoan Tetrahymena thermophila on food safety detection，two strains of protozoan T. thermophila Cu428.2 and B2086.2 were used as substrate to study the biotoxicity of food preservative sodium benzoate（SB）. Effect of SB on T. thermophila was assessed from changes in cell shape，movement style，population growth and superoxide dismutase（SOD） activity after adding SB to the culture of T. thermophila in Neff medium. Cell morphology and movement of T. thermophila were observed under inverted microscope at 6 h after adding 0%，0.01%，0.05%，0.1%，0.25%，0.5%SB to the culture. The results showed that in 0.01% and 0.05% SB，both strains of T. thermophila cells became shrunken and smaller，the speed of cell movement in the media was significantly slower than the control group. While in 0.1%~0.5% SB，cells morphology turned round from oval，holes appeared in the cell membrane，rupture and death cells were found. The higher the concentration of SB was，the greater damage of the cell membrane and the more the apoptotic cells appeared. Population growth curve and 24 h SOD activity of the two strains of T. thermophila cultured in Neff medium were determined in 0.000 1%，0.001%，0.005%，0.01% ，0.05% SB compared to the control group. The results suggested with the increase of SB concentration，population growth rate of T.thermophila decreased and 0.05% SB even killed the original seeded cells，however 0.000 1% SB promoted the population growth. While as the SB concentration increased ，the activity of T. thermophila SOD basically decreased，however，lower concentration of SB could enhanced the activity of SOD in a certain period of time.