Abstract：
A bioassay containing Kluyveromyces marxianus in microtiter plates was used to determine the inhibitory action of 28 antibiotics (aminoglycosides, beta-lactams, macrolides, quinolones, tetracyclines and sulfonamides) against this yeast in whey. For this purpose, the dose-response curve for each antibiotic was constructed using 16 replicates of 12 different concentrations of the antibiotic. The plates were incubated at 40°C until the negative samples exhibited their indicator (5-7h). Subsequently, the absorbances of the yeast cells in each plate were measured by the turbidimetric method (λ=600nm) and the logistic regression model was applied. The concentrations causing 10% (IC10) and 50% (IC50) of growth inhibition of the yeast were calculated. The results allowed to conclude that whey contaminated with cephalosporins, quinolones and tetracyclines at levels close to the Maximum Residue Limits inhibits the growth of K. marxianus. Therefore, previous inactivation treatments should be implemented in order to re-use this contaminated whey by fermentation with K. marxianus.
摘要：
使用在微量滴定板中含有马氏克鲁维酵母的生物测定法来确定28种抗生素的抑制作用（氨基糖苷，β-内酰胺,大环内酯类,喹诺酮类药物,四环素和磺胺类）对抗乳清中的这种酵母。为此,每种抗生素的剂量-反应曲线是使用12种不同浓度抗生素的16次重复构建的.将板在40°C下孵育,直到阴性样品表现出它们的指示(5-7h)。随后，用比浊法(λ=600nm)测定各板酵母细胞的吸光度,并应用logistic回归模型。计算引起酵母生长抑制的10%(IC10)和50%(IC50)的浓度。结果可以得出结论，乳清被头孢菌素污染，喹诺酮类药物和四环素类药物在接近最大残留限量的水平时抑制了K.marxianus的生长。因此,应实施先前的灭活处理，以便通过K.marxianus发酵重新使用这种受污染的乳清。
