"Development of a novel probiotic supplement using lactobacilli with tannase activity"

Ro Osawa, B.V.M, Ph.D.

Department of Bioresource Science

Graduate School of Agricultural Science,

Kobe University,

Abstract 

Tannins comprise a large group of polyphenolic compounds that are widely distributed in the plant kingdom. They have the ability to bind proteins and form insoluble tannin-protein complexes, which are not readily degraded by mammalian digestive enzymes. These complexes potentially reduce the ability of animals to digest plant feed materials. However, some animals have overcome this problem through the degradation of tannins by the gut microflora, as reported for the koala, an arboreal marsupial feeding almost exclusively on tannin-rich Eucalyptus leaves. The koala has a symbiotic relationship with tannin-degrading bacteria (including a bacterium belonging to a previously un-described genus, Lonepinella koalarum) that colonize the hindgut of the animal. Evidence suggests that this symbiosis is one of the most reliable strategies adopted by certain herbivores in order to overcome the nutritional problems associated with plant tannins, thereby endowing them with a greater ecological advantage.

  Meanwhile green tea cathechins contained in green tea and wine are known to have strong anti-oxidative activities, in which they suppress carcinogenesis through “detoxification” of various oxygen-free radical generated in our body, prevent hardening of our arteries by inhibiting oxidation of blood cholesterols, and regulate concentration of sugar in our blood by affecting enzymatic activities related to glycogenesis, and thus have notable health maintenance/ promoting and disease-preventing effects. Majors cathechins contained in green tea include epi-gallo-cathechin-gallate (EGCg) and epi-cathechin-gallate (ECg) that are esterified with gallic acid (GA) like hydrolysable tannins, and epi-gallo-cathechin (EGC) and epi-cathechin (EC). Until now, we have isolated a number of lactobacilli from human fermented vegetables that have activity of tannase, where substrate EGCg is readily hydrolyzed to EGC and GA and those with very limited tannase activity. We have also revealed that tannase produced by Lactobacillus plantarum is structurally and enzymologically different from any known fungal tannases.

  Meanwhile, we have found that EGCg bind quickly with food ingredients (i.e. proteins) to form a complex that is likely to be inabsorbable through the intestine whereas most EGC molecules remain to be free-form, not complexing with the food ingredients.  Based on these findings, we have now come to an idea that if we place one of the lacotacilli with tannase activity in the host intestine, it would hydrolyze the EGCg and ECg complexed with food ingredients to release EGC and EG, which are readily absorbed through our intestine, thereby ensuring a maximum delivery of anti-oxidative power of the green tea to us.  Development of a novel probiotic supplement with use of L. plantarum with high tannase activity has been thus proposed.