Effect of Dimethyl Dicarbonate Combined with Nisin on Cell Membrane Functions of Leuconostoc mesenteroides in Model Juice
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Abstract:
The effects of dimethyl dicarbonate (DMDC) and nisin treatment on the inactivation of Leuconostoc mesenteroides present in model juice and cell membrane functions were investigated. Combined treatment with DMDC and nisin had a fractional bactericidal concentration index of 0.38 (<0.5) against L. mesenteroides, indicating a strong synergistic bactericidal effect of DMDC and nisin. Scanning electron microscopy analysis showed no obvious changes in the cell morphology of L. mesenteroides treated with these antibacterial agents. Treatment with nisin alone increased the membrane permeability of approximately 7% of the cell population; this effect was stronger than that of treatment with DMDC alone. Despite this effect on membrane permeability and the resultant increase in the cellular uptake of extracellular polar substances, nisin treatment could not significantly reduce the loss of intracellular substances. The ultraviolet absorption value of L. mesenteroides cell suspension increased by approximately 60% after treatment with high concentrations of DMDC. To summarize, DMDC and nisin exhibited a synergistic effect on the inactivation of dehydrogenase activity in L. mesenteroides, but not on membrane permeability, loss of intracellular substances, and alteration of intracellular pH.
