Gerós H, Cássio F, Leão C
Centro de Ciências do Ambiente, Departamento de Biologia, Universidade do Minho, Braga, Portugal.
J Food Prot. 2000 Jan;63(1):96-101. doi: 10.4315/0362-028x-63.1.96.
The yeast Dekkera anomala IGC 5153 exhibited a restricted ability to use weak acids as the only carbon and energy sources. Of the monocarboxylic, dicarboxylic, and tricarboxylic acids tested, only acetic acid was used in such a way. The cells were able to grow at acetic acid concentrations of 0.1 to 3% (vol/vol) over a pH range of 3.5 to 5.5, and the specific growth rates decreased exponentially with the increase of the undissociated acetic acid concentration in the culture medium. Transport assays carried out in cells that exhibited higher specific growth rates showed the presence of an acetate-proton symport associated with a simple diffusion component of the undissociated acetic acid, the weight of the latter increasing with the undissociated acid concentration in the culture media. The acetate carrier was shared by propionic, formic, and sorbic acids and was inducible and repressed by glucose and concentrations of undissociated acetic acid in the culture medium above 0.3% (vol/vol). In undissociated acetic acid repression conditions, the lowest values for the yeast specific growth rates were obtained, and the simple diffusion of the undissociated acid was the only mechanism involved in the acetic acid uptake by the cells. The results will be discussed in terms of the high tolerance of D. anomala to the acidic stress conditions present in wine.
异常德克酵母IGC 5153利用弱酸作为唯一碳源和能源的能力有限。在所测试的一元羧酸、二元羧酸和三元羧酸中，只有乙酸能以这种方式被利用。细胞能够在乙酸浓度为0.1%至3%（体积/体积）、pH值范围为3.5至5.5的条件下生长，且比生长速率随着培养基中未解离乙酸浓度的增加呈指数下降。在比生长速率较高的细胞中进行的转运分析表明，存在一种乙酸 - 质子同向转运体，它与未解离乙酸的简单扩散成分相关，后者的权重随着培养基中未解离酸浓度的增加而增加。乙酸载体也被丙酸、甲酸和山梨酸共用，并且可被葡萄糖以及培养基中浓度高于0.3%（体积/体积）的未解离乙酸诱导和抑制。在未解离乙酸抑制条件下，酵母比生长速率达到最低值，未解离酸的简单扩散是细胞摄取乙酸的唯一机制。将根据异常德克酵母对葡萄酒中存在的酸性胁迫条件的高耐受性来讨论这些结果。
