青砖茶渥堆发酵中嗜热细菌筛选、鉴定及产酶特性研究

The Screening,Identification and Enzyme Production of Thermophilic Bacteria in Pile-fermentation of Qingzhuan Tea

渥堆发酵是青砖茶独特品质形成的关键技术环节。对来自青砖茶渥堆发酵样品中的细菌进行高温筛选和鉴定。结果表明,通过筛选得到20株能在高温条件下良好生长的细菌,其中15株菌株能够在含茶汤的培养基中生长。3株菌株的最适生长温度为55℃,为嗜热细菌。结合嗜热菌株的形态特征和16 S rDNA基因序列分析,确定1株为枯草芽孢杆菌(Bacillus subtilis),2株为地衣芽孢杆菌(Bacillus licheniformis)。经嗜热细菌发酵晒青毛茶的产酶试验可知,嗜热菌株在发酵茶叶时能够产生纤维素酶、淀粉酶和单宁酶,其酶活力分别可达215.69、259.28、4.85 U。

Pile-fermentation(PF)is a key step for the formation of the unique quality of Qingzhuan tea.In this study,high-temperature screening and identification of bacteria from PF samples of Qingzhuan tea were carried out.The results show that 20 strains of bacteria that could grow under high temperature conditions were obtained through screening,of which 15 strains could grow on a tea-containing medium.The optimum temperature of 3 thermophilic bacteria strains was 55℃.Combined with the morphological characteristics and the 16 S rDNA gene sequence analysis,it was found that one strain was Bacillus subtilis and the other two were Bacillus licheniformis.The enzyme production test on raw tea by thermophilic bacteria shows that three thermophilic bacteria could produce cellulase,amylase and tannin during tea fermentation,and the enzyme activities reached 215.69 U,259.28 U,and 4.85 U,respectively.