云南小粒咖啡湿法发酵过程中细菌分离与鉴定

咖啡发酵过程中微生物种类、数量的变化及它们的代谢产物如酸等引起的发酵体系变化将直接影响着咖啡的最终品质。本文首次对云南小粒咖啡湿法发酵体系中的pH值和8种有机酸的含量变化进行了测定，并分离和鉴定了发酵过程中的细菌种类。结果发现在整个发酵过程中，pH值变化整体呈下降趋势；本文所测pH值变化与利用HPLC法检测的有机酸草酸、乙酸、乳酸含量变化规律相吻合，而苹果酸、柠檬酸、琥珀酸和丙酸基本上保持不变，其中丙酸含量最低。在20℃下，结合发酵过程中的pH值，采用传统的微生物培养法，对整个发酵过程的细菌进行了分离、纯化和鉴定。结果发现存在大量的产果胶酶的细菌，包括产气肠杆菌Enterobacter aerogenes、肠膜明串珠菌Leuconostoc mesenteroides、枯草芽孢杆菌Bacillus subtilis、蜡样芽孢杆菌Bacillus cereus、巨大芽孢杆菌Bacillus megaterium，冰核活性细菌Erwinia herbicola、肺炎克雷伯菌Klebsiella pneumoniae等，并对分离、鉴定出来的细菌在发酵中所起的作用进行了剖析。

Isolation and identification of bacteria in wet processed Yunnan arabica coffee

The change of microbial species, quantities and their metabolites such as acids, enzymes and etc in the coffee fermentation process would affect the final quality of coffee directly. In this paper, for the first time we determined the change rules of pH value, content variations of the eight kinds of organic acids, isolated and identified the bacterial community in the whole fermentation of Yunnan arabica coffee processed by wet method. It was found that the variation of pH values showed a decrease trend, corresponding with the change of contents of oxalic acid, acetic acid and lactic acid which were measured by high performance liquid chromatography (HPLC) method. However, the contents of malic acid, citric acid, succinic acid and propionic acid remained substantially constant, among which the content of propionic acid was the minimum. Isolation, purification and identification of bacteria were conducted by using the traditional microbial culture method at an environmental temperature of 20℃ and the same pH value as the fermentation system. The results showed a large number of bacteria existed which could metabolize pectinase, including Enterobacter aerogenes, Leuconostoc mesenteroides, Bacillus subtilis, Bacillus cereus, Bacillus megaterium, Erwinia herbicola, Klebsiella pneumonia, etc. And the role of the identified bacteria in the coffee fermentation was also analyzed.