Effect of antibiotics on sedimentary microbiota as characterized by biomarker analysis.

抗生素用于治疗性和预防性治疗。由于饲料浪费和某些抗生素的消化效率较低，很大一部分药物可以释放到环境中并沉积到沉积物中。在孵化场，抗生素也被用于治疗幼虫。在含有链霉素的海水中对贝类幼虫进行处理后，海水被排放到邻近的沿海环境中。因此，抗生素的使用及其在沉积物中的积累可能会影响天然沉积微生物群。为了解抗生素对沉积物微生物生物量及其群落结构的影响，对添加不同浓度链霉素的沉积物进行了磷脂酯连接脂肪酸（PLFA）分析。在孵育过程中，沉积物参数没有明显变化。海水中链霉素浓度高于沉积物中链霉素浓度。此外，在孵育期间，由于添加了链霉素，链霉素的浓度增加。根据总PLFA计算，三种浓度添加链霉素的沉积物中沉积微生物生物量均有所减少。与对照相比，微生物生物量的减少顺序为20 ppm > 10ppm > 5ppm。在孵育结束时，沉积物中总PLFA水平（10和20 ppm链霉素）要么很高，要么与对照值相当，这表明沉积微生物种群可能已产生抗生素耐药性。三种链霉素浓度下沉积物中PLFA群的分布模式不同。聚类分析揭示了链霉素对沉积物微生物群落的影响。多维标度图的结果也表明，由于链霉素的加入和天然微生物群的破坏，PLFA谱发生了变化。

Antibiotics are used in both therapeutic and prophylactic treatment of the stocks. Because of wasted feed and low digestive efficiencies of some antibiotics, a substantial fraction of the drug can be released to the environment and is deposited to the sediment. Antibiotics are also used to treat the larvae in hatcheries. After treating the shellfish larvae in seawater containing streptomycin, the seawater has been discharged into the adjacent coastal environment. Thus antibiotic use and its accumulation in the sediment may influence the natural sedimentary microbiota. In order to know the impact of antibiotics on sedimentary microbial biomass, and its community structure, phospholipid ester-linked fatty acid(PLFA)analysis of sediment supplemented with different concentrations of streptomycin was carried out.Sediment parameters did not show significant changes during the incubation. Concentrations of streptomycin in seawater were higher than that in sediments. Furthermore, concentrations of streptomycin increased during the incubation period due to the addition of streptomycin. Sedimentary microbial biomass, as calculated by total PLFA, was decreased in all the three concentrations of streptomycin added sediments. The decrease of microbial biomass over control was in the order of 20 ppm > 10ppm > 5ppm. At the end of the incubation, levels of total PLFA in sediments(10 and 20 ppm streptomycin)were either high or comparable to the control values indicating that sedimentary microbial populations might have developed antibiotic resistance. The pattern of PLFA groups in sediments was different among the three concentrations of streptomycin used. Cluster analysis of PLFA profiles revealed the changes in microbial communities of sediments amended with streptomycin. The results of multidimensional scaling plot also indicated changes in PLFA profiles due to the addition of streptomycin and also disruption of the natural microbiota.