Department of Animal Science, University of Minnesota, St. Paul, MN 55108, USA.
J Anim Sci. 2013 May;91(5):2395-404. doi: 10.2527/jas.2012-5714. Epub 2013 Mar 5.
Antibiotics are used in ethanol production to control bacteria from competing with yeast for nutrients during starch fermentation. However, there is no published scientific information on whether antibiotic residues are present in distillers grains (DG), co-products from ethanol production, or whether they retain their biological activity. Therefore, the objectives of this study were to quantify concentrations of various antibiotic residues in DG and determine whether residues were biologically active. Twenty distillers wet grains and 20 distillers dried grains samples were collected quarterly from 9 states and 43 ethanol plants in the United States. Samples were analyzed for DM, CP, NDF, crude fat, S, P, and pH to describe the nutritional characteristics of the samples evaluated. Samples were also analyzed for the presence of erythromycin, penicillin G, tetracycline, tylosin, and virginiamycin M1, using liquid chromatography and mass spectrometry. Additionally, virginiamycin residues were determined, using a U.S. Food and Drug Administration-approved bioassay method. Samples were extracted and further analyzed for biological activity by exposing the sample extracts to 10(4) to 10(7) CFU/mL concentrations of sentinel bacterial strains Escherichia coli ATCC 8739 and Listeria monocytogenes ATCC 19115. Extracts that inhibited bacterial growth were considered to have biological activity. Physiochemical characteristics varied among samples but were consistent with previous findings. Thirteen percent of all samples contained low (≤1.12 mg/kg) antibiotic concentrations. Only 1 sample extract inhibited growth of Escherichia coli at 10(4) CFU/mL, but this sample contained no detectable concentrations of antibiotic residues. No extracts inhibited Listeria monocytogenes growth. These data indicate that the likelihood of detectable concentrations of antibiotic residues in DG is low; and if detected, they are found in very low concentrations. The inhibition in only 1 DG sample by sentinel bacteria suggests that antibiotic residues in DG were inactivated during the production process or are present in sublethal concentrations.
抗生素被用于乙醇生产中，以控制细菌在淀粉发酵过程中与酵母争夺营养。然而，目前还没有关于抗生素残留是否存在于酒糟（DG）中，或者它们是否保留其生物活性的公开科学信息。因此，本研究的目的是定量测定 DG 中各种抗生素残留的浓度，并确定残留是否具有生物活性。从美国 9 个州的 43 家乙醇厂每季收集了 20 个湿酒糟和 20 个干酒糟样本。对样本进行了 DM、CP、NDF、粗脂肪、S、P 和 pH 的分析，以描述所评估样本的营养特性。还使用液相色谱和质谱法分析了样本中是否存在红霉素、青霉素 G、四环素、泰乐菌素和维吉尼亚霉素 M1。此外，使用美国食品和药物管理局批准的生物测定方法测定了维吉尼亚霉素残留。对样本进行了提取，并通过将样本提取物暴露于 10（4）至 10（7）CFU/mL 浓度的指示性细菌菌株大肠杆菌 ATCC 8739 和单核细胞增生李斯特菌 ATCC 19115 来进一步分析其生物活性。抑制细菌生长的提取物被认为具有生物活性。样本之间的理化特性有所不同，但与以前的发现一致。13%的样本中含有低浓度（≤1.12mg/kg）的抗生素。只有 1 个样本提取物在 10（4）CFU/mL 时抑制了大肠杆菌的生长，但该样本中未检测到抗生素残留。没有提取物抑制单核细胞增生李斯特菌的生长。这些数据表明，DG 中检测到抗生素残留的可能性很低；如果检测到，残留的浓度也非常低。只有 1 个 DG 样本中的指示性细菌被抑制，这表明抗生素残留在生产过程中失活，或者存在亚致死浓度。
