تاثیر کاربرد لئوناردیت بر جذب آنتی‌بیوتیک سیپروفلوکساسین توسط گیاه تره (allium iranicum)

سیپروفلوکساسین یکی از آنتی‌بیوتیک‌های گروه فلوروکینولون‌ها، به دلیل نیمه‌عمر طولانی و استفاده گسترده در پزشکی و دام‌پزشکی، به‌عنوان آلاینده در محیط خاک تجمع یافته و توسط گیاه جذب می‌شود. از این‌رو در این پژوهش، تاثیر نوعی ماده آلی به نام لئوناردیت بر جذب سیپروفلوکساسین، به‌عنوان روشی برای کاهش تحرک این آلاینده در محیط خاک و کاهش ورود آن به گیاه بررسی شد. به این منظور آزمایشی با غلظت mmol l–1و8.0 سیپروفلوکساسین در مقادیر مختلف لئوناردیت (صفر، 2 و 5 درصد وزنی) در یک خاک آهکی انجام گرفت. سپس تره (allium iranicum) به‌صورت آرایش فاکتوریل در قالب طرح بلوک‌های کامل تصادفی با تیمار لئوناردیت (صفر، 2 و 5 درصد) و سیپروفلوکساسین (صفر و mmol l–1و2) در سه تکرار در گلخانه کشت شد. گیاهان پس از 6 هفته برداشت شده و غلظت سیپروفلوکساسین با استفاده از دستگاه کروماتوگرافی مایع با کارایی بالا (hplc) اندازه‌گیری شد. نتایج نشان داد با مصرف لئوناردیت، جذب سیپروفلوکساسین در خاک افزایش می‌یابد. به‌طوری‌که با کاربرد 5 درصد لئوناردیت میزان جذب (qe) سیپروفلوکساسین از 5102 به mg kg-1و5756 رسید. همچنین ضریب توزیع (kd) سیپروفلوکساسین در حضور 5 درصد لئوناردیت نسبت به شاهد 5 برابر افزایش یافت که بیانگر کاهش تحرک سیپروفلوکساسین به‌علت جذب شدید آن توسط لئوناردیت است. غلظت سیپروفلوکساسین در گیاه تره در اثر کاربرد لئوناردیت به‌طور معنی‌داری کاهش یافت و در حضور 2 و 5 درصد لئوناردیت در مقایسه با شاهد از مقدار µg g-1و5.4 به‌ترتیب به مقادیر 2.3 و µg g-1و7.1 رسید. در کل، به‌نظر می‌رسد کاربرد لئوناردیت می‌تواند برای کنترل سیپروفلوکساسین در محیط خاک و کاهش ورود آن به گیاهان زراعی به‌ویژه سبزیجات موثر باشد. 

the effect of using leonardite on uptake of antibiotic ciprofloxacin by leek (allium iranicum)

abstractciprofloxacin, one of the fluoroquinolone antibiotics, accumulates as a pollutant in the soil environment and is taken up by plants due to the widespread use in human and veterinary medicine and its long half-life. therefore, this study investigated the effect of a type of organic material called leonardite on ciprofloxacin adsorption. this was considered as a method to reduce the mobility of this pollutant in the soil environment and its uptake by plants. for this purpose, an experiment was carried out with a concentration of ciprofloxacin (0.8 mmol l-1) at different levels of leonardite (0, 2 and 5%) in a calcareous soil. leek (allium iranicum) was grown in a factorial experiment based on a randomized complete block design with the treatments of leonardite (0, 2 and, 5 %) and ciprofloxacin (0 and 2 mmol l-1) in three replications. the plants were harvested 42 days after planting and the concentration of ciprofloxacin in the plants were determined using the high performance liquid chromatography (hplc). the results showed that application of leonardite increased the ciprofloxacin adsorption in the soil; the adsorption amount (qe) of ciprofloxacin reached from 5102 to 5756 mg kg-1 with the use of 5% leonardite. in addition, the distribution coefficient (kd) of ciprofloxacin in the presence of 5% leonardite increased five times compared to the control, which indicates the immobilization of ciprofloxacin due to its strong adsorption by leonardite. the concentration of ciprofloxacin in leek plants was significantly reduced through the use of leonardite, and it decreased from 4.5 to 3.2 and 1.7 µg g-1, respectively, in the presence of 2 and 5% leonardite compared to the control. in general, it seems that leonardite usage can be effective to stabilize ciprofloxacin in polluted soil and to reduce its entry into crops, especially vegetables.background and objective: antibiotics are used in treating a wide spectrum of diseases, and are extensively employed to promote animal growth (cycon et al., 2019). as many of those pharmaceuticals are only partially absorbed by the digestive system, a considerable fraction is excreted in its original active form or only partially metabolized. therefore, the use of animal excrement in agriculture represents one of the principal routes of insertion of antibiotics into the environment. within that context, plants, principally those of agricultural interest, will be exposed to those compounds when present in the soil (rocha et al., 2021). hence the present study investigated the effect of organic material of leonardite on ciprofloxacin uptake by leek (allium iranicum).methods: soil (0–20 cm) was collected from an agricultural farm in urmia university, and air-dried. after removal of large pieces of plant materials by screening through a 2-mm sieve, the soil was mixed well and stored at 4 °c until use. pot experiment had two treatments with leonardite (0, 2 and 5%), and ciprofloxacin (0 and 2 mmol l-1) in three replicates. seeds of leek (allium iranicum) were sown at a depth of 0.5 cm in the pots. during the test period, the treated pots were placed in a greenhouse at a temperature of 25 °c and the soil water content was maintained at 0.8 of field capacity (20%w/w), every day by adding appropriate amount of water. the plants were harvested at the 42th day after planting and the ciprofloxacin concentration in the plants was measured using the hplc (liu et al., 2009).results: the results showed that the application of leonardite increased adsorption of ciprofloxacin in the calcareous soil, and decreased concentration of ciprofloxacin in the leek plants. the adsorption amount (qe) of ciprofloxacin reached from 5102 to 5756 mg kg-1 with the use of 5% leonardite. in addition, the distribution coefficient (kd) of ciprofloxacin in the presence of 5% leonardite increased five times compared to the control, which indicates the immobilization of ciprofloxacin due to its strong adsorption by leonardite. the uptake of ciprofloxacin by leek plants was significantly reduced through the use of leonardite, and it decreased from 4.5 to 3.2 and 1.7 µg g-1, respectively, in the presence of 2 and 5% leonardite compared to the control.conclusions: leonardite application is a good choice for controlling ciprofloxacin in the soil environment and preventing its entry into crops, especially vegetables. the solution to reduce pollution caused by ciprofloxacin is to use efficient and low-cost adsorbents such as leonardite. it will be necessary, however, to consider the co-occurrence of antibiotics in existing environmental matrices (instead of focusing on only a single contaminant).references:1. cycon, m., mrozik, a., piotrowska-seget, z., 2019. antibiotics in the soil environment-degradation and their impact on microbial activity and diversity. front. microbial. 338, 1–45.2. rocha, d.c., rocha, c.s., tavares, d.s., calado, s.l.m., gomes, m.p., 2021. veterinary antibiotics and plant physiology: an overview. sci. total environ. 767, 144902.3. liu, f., ying, g., tao, r., zhao, j., yang, j., zhao, l., 2009. effects of six selected antibiotics on plant growth and soil microbial and enzymatic activities. environ. pollut. 157(5), 1636–42.