Viable and Heat-Resistant Microbiota with Probiotic Potential in Fermented and Non-Fermented Tea Leaves and Brews

The live microbiota of tea has not been extensively investigated. This study aimed to identify the live, culturable microbiota from four types of tea with varying oxidation levels, before and after brewing. Tea leaves and brews from oolong and fermented teas were analyzed for total viable counts of aerobic bacteria, lactobacilli, fungi, and <i>Enterobacteriaceae</i>. Cultivation was performed and isolates were identified by Sanger sequencing. Heat resistance was assessed at 70 °C and 90 °C. Random Amplified Polymorphic DNA (RAPD) was used to determine strain-level diversity. Fully oxidized, post-fermented Pu-erh tea had the highest viable bacterial count. Most isolates belonged to <i>Bacillaceae</i>, <i>Staphylococcaceae,</i> and <i>Paenibacillaceae</i>, families associated with soil or human skin. Only two potentially pathogenic species were identified: <i>Staphylococcus epidermidis</i> and <i>Bacillus cereus</i>. In Pu-erh, live bacteria were detected after brewing at 90 °C, including <i>Heyndrickxia coagulans</i>, a spore forming probiotic species. <i>H. coagulans</i> strains remained in vegetative state after hot water exposure and survived at 70 °C, indicating thermotolerance. RAPD-analysis revealed nine distinct <i>H. coagulans</i> strains across six Pu-erh teas. Conclusion: This study provides new insight into the viable microbiota of different teas and their survival during brewing, highlighting safety concerns and probiotic species like <i>H. coagulans</i>.