Peteranderl R, Shotts E B, Wiegel J
Department of Microbiology, University of Georgia, Athens 30602.
Appl Environ Microbiol. 1990 Jun;56(6):1981-3. doi: 10.1128/aem.56.6.1981-1983.1990.
It was shown that the inhibitory effect of kanamycin and streptomycin in a growing culture of Clostridium thermohydrosulfuricum JW 102 is of limited duration. To screen a large number of antibiotics, their stability during incubation under the growth conditions of thermophilic clostridia was determined at 72 and 50 degrees C by using a 0.2% yeast extract-amended prereduced mineral medium with a pH of 7.3 or 5.0. Half-lives were determined in a modified MIC test with Escherichia coli, Staphylococcus aureus, and Bacillus megaterium as indicator strains. All compounds tested were similar at the two temperatures or more stable at 50 than at 72 degrees C. The half-life (t1/2) at pH 7.3 and 72 degrees C ranged from 3.3 h (k = 7.26 day-1, where k [degradation constant] = 1/t1/2) for ampicillin to no detectable loss of activity for kanamycin, neomycin, and other antibiotics. Apparently some compounds (e.g., lasalocid and neomycin) became more potent during incubation (k greater than 0). A change to pH 5.0 caused some compounds to become more labile (e.g., kanamycin) and others (e.g., streptomycin) to become more stable than at pH 7.3.
结果表明，卡那霉素和链霉素对嗜热栖热硫化叶菌JW 102生长培养物的抑制作用持续时间有限。为了筛选大量抗生素，通过使用pH值为7.3或5.0的0.2%酵母提取物改良预还原矿物培养基，在72℃和50℃下测定了它们在嗜热梭菌生长条件下孵育期间的稳定性。在以大肠杆菌、金黄色葡萄球菌和巨大芽孢杆菌为指示菌株的改良MIC试验中测定半衰期。所有测试的化合物在这两个温度下情况相似，或者在50℃比在72℃更稳定。在pH 7.3和72℃下，氨苄西林的半衰期（t1/2）为3.3小时（k = 7.26天-1，其中k[降解常数]= 1/t1/2），而卡那霉素、新霉素和其他抗生素的活性无明显损失。显然，一些化合物（如拉沙洛西和新霉素）在孵育过程中变得更有效（k大于0）。将pH值改为5.0会导致一些化合物变得更不稳定（如卡那霉素），而另一些化合物（如链霉素）则比在pH 7.3时更稳定。
