Primary Study On The Thermophiles From Pu'er Tea During Pile-Fermentation Process

Pu'er tea is made from by post-fermented of the raw tea, in which the microbes play an important role. Many fungi have been found in Pu'er tea, such as Aspergillus spp, Penicillium spp, Rhizopus spp and yeasts, but not bacterium, all of them are mesophilic. Modern fermentation has to last more than 45 days, however, the temperature will be above 50℃when the Pu'er tea is piled and fermented for 3 days, and the temperature will be above 70℃if pile-turning is not carried out. So the existence and contribution of thermophiles should not be neglected.In this paper, the isolation of thermophiles was carried out at beginning, then many thermoduric bacteria isolated were also studied. Samples were collected in PengCheng Tea Factory in Menghai, Yunnan Province. All of the 13 bacteria were isolated through ISP1, ISP4, ISP7 and half nutrition culture medium. In the meanwhile, the colonies seemed similar was counted, then the quantity change of bacteria was tested while the tea was in fermentation.The growth characteristics of the isolates were studied, such as the optimum temperature and pH for growth were tested. The results indicated that ten strains of them were thermoduric bacteria, and three were thermophiles. The optimum pH for growth of the strains was almost neutrality, and the strains could adapt the high temperature environment of Pu'er tea fermentation.The influence of each isolate to Pu'er tea's fermentation was studied. By contrast of the control group, the content changes of polyphenols, caffeine, free amino acid, theaflavin, thearubigin and theabrownine were tested. The results indicated that the strains affected the Pu'er tea fermentation differently.The activities of the isolates'enzymes were studied, and the results indicated that the isoamylase, endoglucanase, exoglucanase, pectinase and alkaline protease activities of each strain's ferment liquid were different, some strains were relatively higher.At last, the 16S rDNA of some strains were amplified, sequenced, sequence alignment and phyligenetic constructed. Then the homologous analyses showed that three of isolates were of Actinomyces. Furthermore, the study of physiological and biochemical characteristics indicated that two isolates present some differences from that of type strains.