College of Resources and Environment, Key Laboratory of Agricultural Environment in Universities of Shandong, Shandong Agricultural University, 61 Daizong Road, Taian, 271018, People's Republic of China.
Environ Geochem Health. 2018 Apr;40(2):763-776. doi: 10.1007/s10653-017-0022-7. Epub 2017 Oct 12.
The production of commercial livestock and poultry often involves using with antibiotics and feed additives, such as oxytetracycline (OTC) and copper (Cu). These are often excreted into the soil by animal feces; hence, combined pollutants may contaminate the soil. To evaluate single and combined toxic effects of OTC and Cu on the soil ecology, changes in quantities of bacteria, fungi, and actinomycetes in the soil were studied over a 28-d incubation period by a plate count method, microbes numbers counted on days 7, 14, 21, and 28. Abundances of ammonia monooxygenase (amoA) gene expression by ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in soil samples also were tested by real-time polymerase chain reactions (RT-PCRs) on day 21. The results revealed that the numbers of bacteria, fungi and actinomycetes and amoA genes copies of AOA and AOB were reduced seriously by exposure to Cu (1.60 mmol/kg). Similarly, the combined pollution treatments (mole ratios of OTC: Cu was 1:2, 1:8, and 1:32) also had inhibitory effect on bacteria, fungi, and actinomycetes numbers and amoA gene copies of AOA and AOB; the inhibitory rate was on obvious growth trend with the increasing mole ratios. Effects from single OTC pollution were found on bacteria (days 7 and 14), fungi (days 7, 14, 21, and 28), and AOA-amoA gene copies (day 21), with promotion at a low concentration (0.05 mmol/kg) and suppression at higher concentrations (0.2 and 0.8 mmol/kg). Also, numbers of bacteria, fungi, and actinomycetes decreased with longer culture times. Combining OTC and Cu led to a higher inhibition of soil microbes than when either chemical was used alone. However, there was no significant relationship between single and combined toxic chemicals because of their complicated interactions, either antagonistic or synergistic. The results also indicated the sensitivity of bacteria, fungi, actinomycetes on toxic chemicals existed difference and that the AOA were more tolerant than the AOB to these chemicals.
商业牲畜和家禽的生产通常涉及使用抗生素和饲料添加剂，如土霉素（OTC）和铜（Cu）。这些通常通过动物粪便排泄到土壤中；因此，复合污染物可能会污染土壤。为了评估 OTC 和 Cu 对土壤生态的单一和联合毒性作用，通过平板计数法研究了 28 天孵育期内土壤中细菌、真菌和放线菌数量的变化，在第 7、14、21 和 28 天计数微生物数量。还通过实时聚合酶链反应（RT-PCR）测试了土壤样品中氨氧化细菌（AOB）和氨氧化古菌（AOA）的氨单加氧酶（amoA）基因表达丰度。结果表明，Cu（1.60 mmol/kg）暴露严重降低了细菌、真菌和放线菌的数量以及 AOA 和 AOB 的 amoA 基因拷贝数。同样，联合污染处理（OTC：Cu 的摩尔比为 1:2、1:8 和 1:32）也对细菌、真菌和放线菌的数量以及 AOA 和 AOB 的 amoA 基因拷贝数有抑制作用；随着摩尔比的增加，抑制率呈明显的增长趋势。单一 OTC 污染对细菌（第 7 和 14 天）、真菌（第 7、14、21 和 28 天）和 AOA-amoA 基因拷贝数（第 21 天）有影响，在低浓度（0.05 mmol/kg）时促进，在高浓度（0.2 和 0.8 mmol/kg）时抑制。此外，随着培养时间的延长，细菌、真菌和放线菌的数量减少。与单独使用任何一种化学物质相比，将 OTC 和 Cu 结合使用会导致土壤微生物受到更高的抑制。然而，由于它们之间复杂的相互作用，无论是拮抗还是协同，单一和联合有毒化学物质之间没有显著的关系。结果还表明，有毒化学物质对细菌、真菌和放线菌的敏感性存在差异，AOA 对这些化学物质的耐受性强于 AOB。
