Occurrence and diversity of yeasts involved in fermentation of West African cocoa beans
Occurrence and diversity of yeasts involved in fermentation of West African cocoa beans
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DOI：
10.1016/j.femsyr.2004.11.002
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发表时间：
2005-02-01
影响因子：
3.2
通讯作者：
Jakobsen, M
中科院分区：
文献类型：
--
作者：
Jespersen, L;Nielsen, DS;Jakobsen, M
在西非加纳的堆积和托盘发酵过程中，在两个不同的场合采集了可可豆样品。通过常规微生物分析和扩增ITS 1 -5.8S rDNA-ITS 2区域，共鉴定了496株酵母菌。对于重要的物种，通过大亚基（26 S）rDNA 5'端的D1/D2结构域的测序来确认鉴定。进行了有机酸和其他碳化合物的同化。对于优势酵母，通过使用脉冲场计数器测定染色体长度多态性（CLP）来检查种内变异。对于堆式发酵，最大酵母细胞计数达到9.1 x 10（7），而对于托盘发酵，最大酵母细胞计数达到6.0 x 10（6）。结果表明，在堆式发酵过程中，克柔假丝酵母是优势菌种，其次是膜产假单胞菌、克氏假单胞菌、季也蒙汉逊酵母和阿萨希丝孢酵母;而在托盘发酵过程中，酿酒酵母和膜产假单胞菌是优势菌种，其次是克柔假丝酵母、克氏假单胞菌、季也蒙汉逊酵母和阿萨希丝孢酵母。Guilliermondii和一些次要的酵母物种。对于所有优势种内的分离株，CLP都很明显，这表明涉及几种不同的菌株。在发酵中。分离到克柔念珠菌（C. krusei）、膜生假单胞菌（P. membranifaciens）、H. guilliermondii、T asahii和Rhodotorula cereus可以在可可豆荚的表面上发现，在某些情况下在生产设备上发现，而例如S.总之，所获得的结果表明，可可豆的发酵是一个非常不均匀的过程，酵母计数和物种组成都有很大的变化。这些变化似乎特别取决于加工过程，但季节和收获后储存也可能影响酵母计数和物种组成。(C)2004年，欧洲微生物学会联合会。Elsevier B. V.出版，保留所有权利。
Samples of cocoa beans were taken on two separate occasions during heap and tray fermentations in Ghana, West Africa. In total 496 yeast isolates were identified by conventional microbiological analyses and by amplification of their ITS1-5.8S rDNA-ITS2 regions. For important species the identifications were confirmed by sequencing of the D1/D2 domain of the 5' end of the large subunit (26S) rDNA. Assimilations of organic acids and other carbon compounds were conducted. For dominant yeasts intraspecies variations were examined by determination of chromosome length polymorphism (CLP) using pulsed-field get electrophoresis.For the heap fermentations maximum yeast cell counts of 9.1 x 10(7) were reached, whereas maximum yeast counts of 6.0 x 10(6) were reached for the tray fermentations. Candida krusei was found to be the dominant species during heap fermentation, followed by P. membranifaciens, P. kluyveri, Hanseniaspora guilliermondii and Trichosporon asahii, whereas Saccharomyces cerevisiae and P. membranifaciens were found to be the dominant species during tray fermentation followed by low numbers of C krusei, P. kluyveri, H. guilliermondii and some yeast species of minor importance. For isolates within all dominant species CLP was evident, indicating that several different strains are involved. in the fermentations. Isolates of C krusei, P. membranifaciens, H. guilliermondii, T asahii and Rhodotorula glutinis could be found on the surface of the cocoa pods and in some cases on the production equipment, whereas the origin of e.g. S. cerevisiae was not indicated by the results obtained.In conclusion, the results obtained show that fermentation of cocoa beans is a very inhomogeneous process with great variations in both yeast counts and species composition. The variations seem to depend especially on the processing procedure, but also the season and the post-harvest storage are likely to influence the yeast counts and the species composition. (C) 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.