In vitro cholesterol-lowering properties of Lactobacillus plantarum AN6 isolated from aji-narezushi

Aji‐narezushi is a traditional lactic acid‐fermented fish. In this study, we screened for lactose‐utilizing, acidophilic, bile‐resistant and cholesterol‐lowering lactic acid bacteria (LAB) from aji‐narezushi for use as starter strains for fermented foods, as well as for use as probiotics. Of the 301 LAB isolates, 277 fermented lactose, and among these, 171 grew in de Man, Rogosa and Sharpe broth adjusted to pH 3·5. Thirty‐four of the isolates were grown in a broth containing 3% (w/v) bile. All of the isolates were lactobacilli. Seven isolates that demonstrated cholesterol‐lowering activity in ethanolic solution were selected. All of the isolates were identified as Lactobacillus plantarum. Lactobacillus plantarum AN6 showed the highest cholesterol‐lowering activity. AN6 was more resistant to acid, salt and bile than the type strain NBRC15891T. One‐half of the cholesterol‐lowering effect remained after boiling AN6 for 10 min. The Fourier transform infrared (FT‐IR) analysis indicated that the content of cell wall polysaccharides in AN6 is higher than ones in the type strain. These results indicate that Lact. plantarum AN6 can be used as a profitable starter organism and probiotic. Lactobacillus plantarum AN6 was isolated from aji‐narezushi. Cholesterol‐lowering activity of AN6 was higher than ones of the type strain. Cell surface of AN6 was rough. FT‐IR analysis indicated that the content of cell wall polysaccharides of AN6 is higher than ones in the type strain. These results indicate that AN6 can be used as a new profitable starter and probiotic.