No abstract

This study aimed to investigate the biological activities of aqueous extract of the edible insect Protaetia brevitarsis seulensis (PB) larvae fermented by Bacillus subtilis KACC 91157. On the other hand, the soluble solids of PB increased reaching the maximum level about 5.6 °Brix after 7 days of fermentation. Protein concentration also increased during the fermentation period and the highest protein content was measured in the PB fermented for 6 days with B. subtilis. Protein content was analyzed by SDS (sodium dodecyl sulfate)-polyacrylamide gel electrophoresis, and it was observed that most of the protein bands were completely degraded after 3 days of fermentation. The phenolic and flavonoid compounds were higher in the fermented group than the non-fermented group. They showed the highest amounts during 2-3 days of fermentation. The highest reducing power and DPPH (α,α'-diphenyl-β-picrylhydrazyl) radical scavenging activity were observed in PB fermented for 3 days, and no major changes occurred during the subsequent fermentation. Similarly, fibrinolytic activity was the highest at the 3 rd day of fermentation. This experiment showed that fermentation of PB for 3 days by B. subtilis is the optimum time to achieve the desired physicochemical properties and highest biological activities.

We investigated the effect of Protaetia brevitarsis seulensis larvae fermented by Bacillus subtilis (FPb) on the orotic-acid-induced fatty livers of Sprague-Dawley (SD) rats. FPb was found to reduce SD-rat organ size and serum triglyceride levels. Conversely, serum lipid levels were elevated to normal levels, which helped to improve the liver. Total lipid and free fatty acid levels in the serum were lower in the group fed with FPb than in the group fed with Protaetia brevitarsis seulensis larvae (NPb) and showed an overall improvement in lipid metabolism. In a similar manner, the FPb group exhibited an HDL-cholesterol content that was similar to the normal group fed with NPb compared to the group fed only with orotic acid. On the other hand, the group administered with a high concentration of FPb exhibited intracellular toxicity. Pathological observations of liver tissue also revealed that hepatic lobular liver cells were uniformly arranged in the group fed with FPb powder, thereby improving the fatty liver. Protaetia brevitarsis seulensis larvae fermented by Bacillus subtilis improves the non-alcoholic fatty liver and can be used as an effective health food material for enhancing liver function.