Biochemical Studies on Oxidation of catechin by Pseudomonas cepasia

澄清了不同地区后热发酵茶的风味成分.此外，我们已经从后加热的发酵茶中分离出许多微生物。通过使用这些微生物，风味成分的影响进行了检查。其中，对影响茶儿茶素的假单胞菌进行了研究。在后热发酵茶的生产过程中，从茶桶中分离到一株假单胞菌。该微生物包含在Goishi-cha（GOS3）中。Laphet-so（PBJ17）和Miang（LAO P.D. R B2TS2）。P.cepasia是一种阴性杆菌。此外，检查了P.cepasia的性质。结果，如此分离的P.cepasia显示类似于典型培养物的S形生长曲线。分离的P.cepasia即使在100 ℃的热处理中也保持稳定，因此显示出较高的热稳定性。关于最适pH值，发现与典型培养物相比，该分离的P.cepasia在碱性区域生长。在模型实验中。在后热发酵茶生产中将细叶假单胞菌添加到桶中，并监测风味成分的变化。结果，儿茶素含量降低。特别地，（-）-表没食子儿茶素没食子酸酯（（-）-EGCg）显示出显著的降低。此外，对似乎在很大程度上影响儿茶素氧化的酶进行了检测。因此，发现在培养期间通过添加儿茶素降低了（-）-EGCg等。还阐明了降解儿茶素的能力不是出现在P.cepasia培养基中，而是出现在细胞中。为了从细胞中提取酶，使用法式压榨机破碎细胞是一种有效的手段。还发现儿茶素中的（-）-EGCg是主要底物。

We have clarified flavor components of post heated fermented teas in various are as. Also, we have isolated a number of microorganisms from post-heated fermented teas. By using these microorganisms, effect on flavor components were examined. Among all, Examination was made on Pseudomonas cepasia (P. cepasia) affecting tea catechins. P. cepasia was isolated front a bucket in the process of post-heated fermented tea production . This microorganism was contained in Goishi-cha (GOS3). Laphet-so (PBJ17) and Miang (LAO P.D.R B2TS2). P. cepasia was a grain-negative bactellium. Further, properties of P. cepasia was examined. As a result, the thus isolated P. cepasia showed an S-shape growth curve similar to the type culture . The isolated P. cepasia remained stable even in a heat treatment at 100℃, thus showing a high heat stability. Regarding the optimum pH value, it was found out that this isolated P. cepasia grew in the alkaline region compared with the type culture. In a model experiment . P. cepasia was added in the bucket in the post-heated fermented tea production and changes in the flavor components ware monitored. As a result, the catechin content was decreased. In particular, (-)-epigallocatechin gallate((-)-EGCg) showed a remarkable decrease- Also, examination was made on enzymes seemingly largely affecting the oxidation of catechin- Thus it was found out that (-)-EGCg, etc. were decreased by adding catechin during the culture period. It was also clarified that the capability of degrading catechin appeared not in the P. cepasia culture medium but in the cells. To extract the enzymes from the cells, cell disruption with the use of a French press was an efficacious means . It was also found out that (-)-EGCg, among catechins, served as the major substrate.