Abstract
The present investigation was designed to determine whether any synergism exists between surfactin and natto in improving the lipid metabolism of rat. Rats were divided into four groups and fed four different diets each having a high cholesterol and lard content. The diet of the control group did not contain either surfactin or natto, whereas the three experimental groups were given a diet containing surfactin alone (surfactin group), natto alone (natto group), and a mixture of surfactin and natto (surfactin-natto group). Analyses revealed that the levels of serum lipids, total cholesterol (T-chol), arteriosclerosis index (AI), and triacylglycerol (TG) were decreased significantly or tended to decrease in the three experimental groups. With regard to the amount of lipids in liver, total lipid (TL) was decreased in the surfactin-natto group, cholesterol was decreased in both the surfactin and the surfactin-natto groups, and TG was decreased in all the experimental groups. The cholesterol excretion ratio was increased in the surfactin-natto group and cholic acid excretion was markedly increased in all the experimental groups, while the enzyme activity responsible for lipid synthesis in the liver was decreased in the natto and surfactin-natto groups. These results indicate that surfactin and natto exhibit synergism in improving the lipid metabolism of rats by lowering the levels of serum T-chol and liver TG and by increasing the cholesterol excretion ratio, suggesting that the development of surfactin-rich natto would be of potential value.
