Vilhelmsson Oddur, Miller Karen J
Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA.
Appl Environ Microbiol. 2002 May;68(5):2353-8. doi: 10.1128/AEM.68.5.2353-2358.2002.
The pyruvate dehydrogenase multienzyme complex (PDHC) was found to be upregulated by osmotic stress in the osmotolerant pathogen Staphylococcus aureus. Upregulation was detectable in the levels of both activity and protein and was judged to be about fourfold when sodium chloride was used to adjust the water activity (a(w)) of the growth medium to 0.94. The upregulation of the PDHC was also found to be humectant dependent and was greatest when impermeant, nonmetabolizable humectants were used to adjust a(w). Further experiments provided evidence that in addition to osmotic upregulation, the PDHC complex is also subject to catabolite repression, thus providing a possible explanation for the observation that high concentrations of carbohydrates are generally more inhibitory to the growth of this bacterial pathogen than are high concentrations of salts.
在耐渗透压病原体金黄色葡萄球菌中，丙酮酸脱氢酶多酶复合物（PDHC）被发现会因渗透压应激而上调。活性和蛋白质水平均能检测到上调，当用氯化钠将生长培养基的水活度（a(w)）调节至0.94时，上调幅度约为四倍。还发现PDHC的上调取决于保湿剂，当使用不可渗透、不可代谢的保湿剂来调节a(w)时上调幅度最大。进一步的实验提供了证据，表明除了渗透压上调外，PDHC复合物还受到分解代谢物阻遏，从而为以下观察结果提供了一种可能的解释：高浓度碳水化合物通常比高浓度盐对这种细菌病原体的生长抑制作用更强。
