Smith D J, Craig A M, Duringer J M, Chaney R L
Animal Metabolism-Agricultural Chemicals Research Unit, USDA ARS, 1605 Albrecht Blvd. Fargo, North Dakota, 58105-5674, USA.
Environ Sci Technol. 2008 Apr 1;42(7):2563-9. doi: 10.1021/es702601n.
The compound 2,4,6-trinitrotoluene (TNT) is a persistent contaminant of some industrial and military sites. Biological bioremediation techniques typically rely on the immobilization of TNT reduction products rather than on TNT mineralization. We hypothesized that sheep ruminal microbes would be suitable for TNT destruction after phytoremediation of TNT-contaminated soils by cool-season grasses. Therefore we investigated the fate of [14C]TNT in ruminating sheep to determine the utility of ruminant animals as a portion of the bioremediation process. Three wether sheep were dosed with 35.5 mg each of dietary unlabeled TNT for 21 consecutive days. On day 22 sheep (41.9 +/- 3.0 kg) were orally dosed with 35.5 mg of [14C]TNT (129 microCi; 99.1% radiochemical purity). Blood, urine, and feces were collected at regular intervals for 72 h. At slaughter, tissues were quantitatively collected. Tissues and blood were analyzed for total radioactive residues (TRR); excreta were analyzed for TRR, bound residues, and TNT metabolites. Plasma radioactivity peaked within 1 h of dosing and was essentially depleted within 18 h. Approximately 76% of the radiocarbon was excreted in feces, 17% in urine, with 5% being retained in the gastrointestinal tract and 1% retained in tissues. Parent TNT, dinitroamino metabolites, and diaminonitro metabolites were not detected in excreta. Ruminal and fecal radioactivity was essentially nonextractable using ethyl acetate, acetone, and methanol; covalent binding of fecal radioactive residues was evenly distributed among extractable organic molecules (i.e., soluble organic matter, soluble carbohydrate, protein, lipid, and nucleic acid fractions) and undigested fibers (cellulose, hemicellulose, and lignin). This study demonstrated that TNT reduction within the ruminant gastrointestinal tract leads to substantial immobilization of residues to organic matter, a fate similar to TNT in other strongly reducing environments.
化合物2,4,6-三硝基甲苯（TNT）是一些工业和军事场地的持久性污染物。生物修复技术通常依赖于TNT还原产物的固定化，而非TNT的矿化作用。我们推测，在利用冷季型草对受TNT污染的土壤进行植物修复后，绵羊瘤胃微生物将适合用于TNT的降解。因此，我们研究了反刍绵羊体内[14C]TNT的归宿，以确定反刍动物作为生物修复过程一部分的效用。三只去势公羊连续21天每天投喂35.5毫克未标记的日粮TNT。在第22天，给绵羊（体重41.9±3.0千克）口服35.5毫克[14C]TNT（129微居里；放射化学纯度99.1%）。在72小时内定期采集血液、尿液和粪便。屠宰时，定量采集组织。分析组织和血液中的总放射性残留（TRR）；分析排泄物中的TRR、结合残留和TNT代谢物。给药后1小时内血浆放射性达到峰值，18小时内基本耗尽。约76%的放射性碳通过粪便排出，17%通过尿液排出，5%保留在胃肠道，1%保留在组织中。排泄物中未检测到母体TNT、二硝基氨基代谢物和二氨基硝基代谢物。瘤胃和粪便放射性物质基本上不能用乙酸乙酯、丙酮和甲醇提取；粪便放射性残留的共价结合均匀分布在可提取有机分子（即可溶性有机物、可溶性碳水化合物、蛋白质、脂质和核酸部分）和未消化纤维（纤维素、半纤维素和木质素）之间。本研究表明，反刍动物胃肠道内的TNT还原导致残留物质大量固定到有机物上，这一归宿与其他强还原环境中的TNT相似。
