Tannin-Tolerant and Extracellular Tannase Producing Isolated from Traditional Fermented Tea Leaves and Their Probiotic Functional Properties.

A total of 117 strains were isolated from Miang, a culture relevant fermented tea of northern Thailand. These strains were collected from 16 sampling sites in north Thailand. In this collection 95 isolates were tannin-tolerant capable of growth on nutrient agar supplemented with 0.5% (/) total tannins from tea leaves extract (TE). The strains were also positive for pectinase, xylanase and amylase activity, while 91 and 86 isolates were positive for cellulase and β-mannanase, respectively. Only 21 isolates producing extracellular tannase were selected for further characterization. Identification by 16S rRNA gene sequence analysis revealed that more than 50% (11 of 21 isolates) were , whereas the remaining were (3), (3), (3) and (1). K34.2 produced the highest extracellular tannase activity of 0.60 U/mL after cultivation at 37 °C for 48 h. In addition, all 21 isolates were resistant to 0.3% (/) bile salt, sensitive to gentamicin, erythromycin, vancomycin and kanamycin and also tolerant to acidic condition. Cell hydrophobicity varied from 9.4 to 80.4% and neutralized culture supernatants of some isolates showed bacteriocin producing potentiality against serovar Typhimurium TISTR 292. All tested probiotic properties indicated that K19.3, K34.2 and K19.1 had high probiotic potential. This is the first report describing tannin-tolerant and their extracellular tannase producing capability in Miang, a traditional fermented tea of Thailand.