Probiotic Potential of a Novel Vitamin B2-Overproducing Lactobacillus plantarum Strain, HY7715, Isolated from Kimchi

Abstract

Vitamin B2, also known as riboflavin, is essential for maintaining human health. The purpose of this study was to isolate novel lactic acid bacteria that overproduce vitamin B2 and to validate their potential as probiotics. In this study, Lactobacillus plantarum HY7715 (HY7715) was selected among lactic acid bacteria isolated from Kimchi. HY7715 showed a very high riboflavin-producing ability compared to the control strain due to the high expression of ribA, ribB, ribC, ribH, and ribG genes. HY7715 produced 34.5 ± 2.41 mg/L of riboflavin for 24 h without consuming riboflavin in the medium under optimal growth conditions. It was able to produce riboflavin in an in vitro model of the intestinal environment. In addition, when riboflavin deficiency was induced in mice through nutritional restriction, higher levels of riboflavin were detected in plasma and urine in the HY7715 administration group than in the control group. HY7715 showed high survival rate in simulated gastrointestinal conditions and had antibiotic resistance below the cutoff MIC value suggested by the European Food Safety Authority; moreover, it did not cause hemolysis. In conclusion, HY7715 could be considered a beneficial probiotic strain for human and animal applications, suggesting that it could be a new alternative to address riboflavin deficiency.

Effects of L. plantarum HY7715 on the Gut Microbial Community and Riboflavin Production in a Three-Stage Semi-Continuous Simulated Gut System

“…Studies on the selection and effectiveness of probiotic strains with an excellent riboflavin-producing ability have been reported, and the production of riboflavin after intestinal settlement through probiotics has been reported to have a double effect on the basic functionality of probiotics [29,30]. In our previous studies, we demonstrated the vitamin B2 production ability and high survival rate of the L. plantarum HY7715 (HY7715) strain against gastric and bile acids, and the safety of the HY7715 strain was confirmed through Minimum Inhibitory Concentration (MIC) and hemolysis tests [31].…”

Spontaneous Riboflavin-Overproducing Limosilactobacillus reuteri for Biofortification of Fermented Foods

“…In this study, we characterized the healthy human isolate L. reuteri AMBV339 with natural riboflavin production levels of 18.36 μg/ml in standard laboratory conditions. Based on the available literature, L. reuteri AMBV339 demonstrates the highest riboflavin production levels described for non-modified lactobacilli isolates in standard non-optimized growth conditions (MRS broth, 37°C, 24 h), which so far appear to be in the maximum range of 3–5 μg/ml ( 14 , 16 – 18 ). Although genetic modification of the riboflavin biosynthesis pathway in Lactococcus lactis NZ9000 resulted in overproduction up to 24 μg/ml of riboflavin ( 50 ), live genetically modified strains are currently not allowed to be used for food fortification in the European Union according to the opinion of the EFSA Panel on Genetically Modified Organisms ( 51 ).…”

“…To our knowledge, this is the first study describing an L. reuteri strain with a spontaneous riboflavin-overproducing phenotype. Besides the well-reported investigation and applications of overproducing L. plantarum strains ( 16 , 18 , 52 – 56 ) only few other species of food-grade bacteria including L. lactis ( 50 ), Leuconostoc mesenteroides, Propionibacterium freudenreichii ( 43 ); Limosilactobacillus fermentum ( 57 ); Weissella cibaria , and Leuconostoc spp. ( 58 ) have been reported for the vitamin B2 bio-enrichment of fermented foods.…”

“…Riboflavin production is a highly strain-specific property of lactobacilli ( 14 ). While some probiotic strains such as Lacticaseibacillus rhamnosus GG ( 14 , 15 ) cannot produce this vitamin, riboflavin production levels up to 3–5 μg/ml have been described for natural riboflavin-producing lactobacilli isolates such as Lactiplantibacillus plantarum strains M5MA1-B2 and HY7715 grown under standard non-optimized laboratory conditions ( 16 – 18 ). The ability of specific lactobacilli to increase riboflavin content in plant-based alternatives for milk is especially important, since these alternatives gain worldwide popularity, yet they often lack specific vitamins.…”

“…Moreover, the acidification capacity of these bacteria can inhibit pathogenic growth, typically resulting in longer shelf life ( 20 ). In addition to the ability of the lactobacilli to produce riboflavin in a range of food matrices, it can be beneficial if the selected strains survive the gastrointestinal tract, so that the vitamins can be produced in situ at the target site to further enhance delivery and maximize the chance of reaching required daily intake levels ( 16 , 21 ).…”