In this study, we investigated the diversity of AAB from fermenting cocoa and the production of acetic acid in response to various environmental conditions. Ribosomal 16S gene sequence analysis and PCR-RFLP showed a restricted microbiota mainly composed of Acetobacter pasteurianus, Acetobacter tropicalis and Acetobacter okinawensis sp., consistently found in all six regions studied. Meanwhile Acetobacter malorum, Acetobacter ghanensis and Gluconobacter oxydans were isolated as minor species in specific regions. The dominant species were mainly isolated in the first 72 h period of natural cocoa fermentation while the minor species were present toward the later stages. Acetobacter okinawensis, a newly isolated species, was able to yield an unusually high quantity, up to 62 g/L of acetic acid at 30 °C. However, a shift of temperature to 35 °C severely impaired acid production in most strains of this species. While acetic acid production increases for up to 6 days in Acetobacter okinawensis and Acetobacter pasteurianus, it decreases beyond 4 days in Acetobacter tropicalis strains. The production of acetic acid was strongly dependent on environmental conditions, with optimal production between pH 4 and 5, under ethanol concentration below 8% and temperatures above 35–40 °C, corresponding to conditions prevailing in the first half of fermentation process. Acetobacter tropicalis was more productive at higher ethanol concentration and Acetobacter okinawensis at low pH. Species diversity and different behavior of strains highlight the importance of valuable starter selection for well-controlled cocoa fermentation.

中文翻译：

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象牙海岸可可发酵所涉及的乙酸细菌（AAB）：物种多样性和乙酸生产性能。

在这项研究中，我们调查了可可豆发酵AAB的多样性以及响应各种环境条件产生的乙酸。核糖体16S基因序列分析和PCR-RFLP表现出有限的微生物主要由醋酸杆菌，醋热带和醋okinawensis属，在所研究的所有六个地区不断发现。同时，在特定区域中分离出次要种为苹果醋杆菌，加纳醋杆菌和氧化葡糖杆菌。主要的物种主要是在自然可可发酵的前72小时内分离出来的，而次要的物种则出现在后期。刚分离出的一类醋杆菌（Acetobacter okinawensis）能够产生异常高的数量，在30°C时乙酸的含量高达62 g / L。但是，温度移至35°C会严重损害该物种大多数菌株的产酸能力。虽然在醋酸醋杆菌和巴氏醋杆菌中乙酸产量最多增加6天，但在热带醋杆菌菌株中乙酸产量减少超过4天。乙酸的生产在很大程度上取决于环境条件，在乙醇浓度低于8％且温度高于35–40°C（与发酵过程的前半段普遍存在的条件）相对应的情况下，pH值在4到5之间的最佳产量。热带醋杆菌在较高的乙醇浓度下产量较高，而在较低的pH值下产醋杆菌。物种的多样性和菌株的不同行为突出了对可控可可发酵进行有价值的起子选择的重要性。