Frohlich B T, d'Alarcao M, Feldberg R S, Nicholson M L, Siber G R, Swartz R W
Department of Chemical Engineering and the Biotechnology Center, Tufts University, Medford, MA 02155, USA.
J Biotechnol. 1996 Feb 28;45(2):137-48. doi: 10.1016/0168-1656(95)00155-7.
Palmitic, palmitoleic and stearic acids were found in the extracted cellular lipids of virulent Bordetella pertussis as unesterified acids in confirmation of earlier taxonomic analyses. The same free fatty acids (FFAs) were found in the spent culture supernatant in concentrations higher than in the uninoculated medium, indicating that they are released into the extracellular medium. These long-chain fatty acids are known to inhibit the growth of B. pertussis at concentrations as low as 1 ppm. Measurement of palmitate cell-medium partitioning demonstrated a strong tendency of FFAs for cellular adsorption. Inhibition kinetics indicated that the cell-bound FFA was responsible for inhibition and that the specific cellular FFA concentrations actually found during growth were similar to those determined to be inhibitory. Autoinhibition by these endogenous FFAs provides an explanation of the low maximum cell concentrations currently attainable in liquid media. Addition of soluble dimethyl-beta-cyclodextrin (MebetaCD) to FFA-inhibited cultures resulted in a rapid reversal of the inhibition. A corresponding shift in the distribution of FFAs from the cells to the extracellular medium demonstrated that MebetaCD sequesters FFAs. Although MebetaCD did not increase final cell concentrations and even had an adverse effect on growth at concentrations above 1 g l-1, it did (at 1 g l-1 extend the initial period of high growth rate leading to shorter cultivation times.
在有毒百日咳博德特氏菌提取的细胞脂质中发现了棕榈酸、棕榈油酸和硬脂酸，它们以未酯化酸的形式存在，这证实了早期的分类学分析。在培养后的上清液中也发现了相同的游离脂肪酸（FFA），其浓度高于未接种培养基中的浓度，这表明它们被释放到细胞外培养基中。已知这些长链脂肪酸在低至1 ppm的浓度下就能抑制百日咳博德特氏菌的生长。棕榈酸细胞 - 培养基分配的测量表明FFA具有强烈的细胞吸附倾向。抑制动力学表明，细胞结合的FFA是抑制作用的原因，并且在生长过程中实际发现的特定细胞FFA浓度与确定具有抑制作用的浓度相似。这些内源性FFA的自抑制作用解释了目前在液体培养基中可达到的低最大细胞浓度。向受FFA抑制的培养物中添加可溶性二甲基 - β - 环糊精（MebetaCD）导致抑制作用迅速逆转。FFA从细胞到细胞外培养基的相应分布变化表明MebetaCD螯合了FFA。尽管MebetaCD没有增加最终细胞浓度，甚至在浓度高于1 g l-1时对生长有不利影响，但它（在1 g l-1时）延长了高生长速率的初始阶段，从而缩短了培养时间。
