Determination of the Absorption, Translocation, and Distribution of Imidacloprid in Wheat

Neonicotinoids, a class of insecticides, are widely used because of their novel modes of action, high insecticidal activity, and strong root uptake. ...

shandong agricultural university

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.

Toxic effects of oxytetracycline and copper, separately or combined, on soil microbial biomasses.

The negative effects of residues from antibiotics and heavy metals in agricultural soils are becoming an increasingly frequent concern. To evaluate the toxicity and interaction of antibiotics and heavy metals, enrofloxacin (ENR) and cadmium (Cd) were used as targets to study the individual effects of ENR (0.025, 0.1, 0.4mmol/kg) and Cd (0.4mmol/kg) and their combined effects (mole ratios of ENR to Cd of 1: 1, 1: 4 and 1: 16) on soil microbial biomass and function on days 7, 14, 21 and 28 of the study. The results demonstrated that microbial populations, which were counted during 4 sampling periods, were mainly in the order of bacteria>actinomycetes>fungi. The ammonia monooxygenase (amoA) gene copies of ammonia-oxidizing archaea (AOA) were more abundant than ammonia-oxidizing bacteria (AOB) on days 14 and 21. Soil bacteria, fungi, and actinomycetes numbers and amoA gene abundances of AOB and AOA in soils were inhibited to varying degrees by the single and combined effects of ENR and Cd; the higher the concentration of the treatments, the stronger the inhibition. The combined toxicity of ENR and Cd on soil microbes and AOA- and AOB-amoA genes was stronger than when either chemical was used alone; the interaction effects of ENR and Cd were mainly antagonistic. Moreover, the ratios of bacteria/fungi declined significantly on days 14, 21 and 28; the proportions of AOA- and AOB-amoA were altered with the addition of ENR and Cd. Thus, ENR and Cd had significant negative effects on the soil microbial community, especially when both contaminants were present.

Individual and combined effects of enrofloxacin and cadmium on soil microbial biomass and the ammonia-oxidizing functional gene.

Heavy metals and antibiotics residues in agricultural soils are attracting more and more attention. A laboratory study was conducted to evaluate the single and combined effects of sulfadimidine (SM2) (0.05, 0.20, 0.80 mmol/kg) and copper (Cu) (1.60 mmol/kg) on soil microbial biomasses and ammoxidation microorganisms abundances after 7, 14, 21 and 28 days. The results demonstrated that the single and combined contaminations had a significant and persistent inhibitory effect on soil bacteria, fungi and actinomycetes populations and amoA gene copies of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) (Except SM2 0.05 and 0.20 mmol/kg on 7 and 14 d and SM2 0.05 mmol/kg on 21 d led to a stimulatory effect on fungi and AOA-amoA gene, respectively). With higher dosage and longer exposure time, the toxic effect of single and combined contaminants on soil bacteria, fungi and actinomycetes as well as on the amoA gene of AOA and AOB was greatly reinforced. Combined contaminants produced more toxicity than the chemicals were used alone. Overall, the interaction effects of SM2 and Cu on bacteria (on 14, 21 and 28 d), fungi and AOA-amoA were mainly synergism, in contrast, on actinomycetes (on 14, 21 and 28 d) and AOB-amoA were mainly antagonism. The order of the toxic effects of the single Cu and combined contaminants on microbial activity was: bacteria > actinomycetes > fungi. Furthermore, AOB-amoA was more sensitive to both contaminants toxicity than AOA-amoA, while AOA-amoA gene copies were greater than AOB-amoA gene copies about one order of magnitude.

Separate and joint eco-toxicological effects of sulfadimidine and copper on soil microbial biomasses and ammoxidation microorganisms abundances.

Antibiotics and heavy metals have long-term potential toxicity to the environment, and their residuals in agricultural soils are receiving more and more attention. To evaluate the ecotoxicological effects of enrofloxacin and cadmium on soil enzymatic activities and microbial community structure, soil samples were exposed to individual and combined contaminants over 28 days. The results indicated that the toxic effects of enrofloxacin alone on soil enzymatic activities were relatively small and showed no concentration dependence. In contrast, significant inhibition of soil enzymatic activities was observed upon cadmium contamination by itself. Overall, the combination of two contaminants also has toxic effect on enzymatic activities; an antagonism between enrofloxacin and cadmium was observed. On 14 and 21 days, individual enrofloxacin and cadmium reduced average well color development (AWCD), Shannon, McIntosh, Simpson indices, and substrate utilization, except for Shannon, McIntosh, Simpson indices of the cadmium 0.4 mmol/kg treatment were higher than the control on 21 days. In general, combined treatments led to higher value of these microbial diversity indicators than those found under separate contamination, although there were some exceptions. With the increase in enrofloxacin concentration, the utilization of any carbon source by the microorganisms gradually decreased. In addition, the AWCD value and substrate utilization decreased as time increased. In the separate and combined contaminant treatments, the order of substrate utilization by soil microorganisms was aliphatics > amino acids > saccharides > metabolites. Thus, enrofloxacin and cadmium had a variable but generally negative influence on soil enzymatic activities and microbial community structure.

Toxicity of enrofloxacin and cadmium alone and in combination to enzymatic activities and microbial community structure in soil.

Livestock manure is a major reservoir of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). This study investigated the distribution characteristics of ARB, ARGs in fresh and composted manures of traditional breading industry in rural areas in China. Samples collected were naturally piled without professional composting, and will be applied to farmland. The real-time quantitative polymerase chain reaction (qPCR) results showed the presence of ten target ARGs and two mobile genetic elements (MGEs) in the tested manure samples. The relative abundance of tetracycline and sulfonamide resistance genes (TRGs and SRGs) was generally higher than that of macrolide resistance genes (MRGs), followed by quinolone resistance genes (QRGs). There were significant positive correlations between the abundance of sul1, sul2, tetW and MGEs (intl1, intl2). In addition, the distribution of target ARGs was associated with the residual concentrations of doxycycline (DOX), sulfamethazine (SM2), enrofloxacin (ENR) and tylosin (TYL). Overall, a total of 24 bacterial genera were identified. The resistance rates of ARB were 17.79%-83.70% for SM2, followed 0.40%-63.77% for TYL, 0.36%-43.90% for DOX and 0.00%-13.36% for ENR, which showed a significant dose-effect. This study also demonstrated that the abundance of clinically relevant ARB and ARGs in chicken, swine and cow fresh manures significantly greater than that in composted manures, and chicken and swine manures had higher proportion of ARB and higher abundance of ARGs than that in cow manures.

Distribution characteristics of antibiotic resistant bacteria and genes in fresh and composted manures of livestock farms.

Composted livestock and poultry manure, which may contain antibiotic resistance genes (ARGs), is widely used as natural fertilizer in China. But the influence of soil types on ARGs is not well characterized, particularly at greenhouse sites with long-term manure application. We investigated the distribution of ARGs in the cinnamon, fluvo-aquic and saline-alkali soils in greenhouse of Yellow River Delta region, China. A total of 193 ARGs subtypes were detected, with multidrug and aminoglycoside resistance genes as the most universal ARGs subtypes. Soil types influenced the ARGs distribution, where higher levels of diversity and relative abundance of ARGs in the fluvo-aquic and saline-alkali soils compared with those in the cinnamon soils. Among abiotic factors, sand, pH and Zn contributed more to the pattern of ARGs in the cinnamon soils, whereas sand and Cd, clay and Pb contributed the most in the fluvo-aquic and saline-alkali soils respectively. Furthermore, positive correlations between the relative abundances of ARGs and mobile genetic elements (MGEs) in the fluvo-aquic soils, suggesting higher dissemination potential of ARGs in this type of soil. Overall, MGEs played a positive primary role in the ARGs distribution in greenhouse soil than heavy metal co-selection and soil physicochemical properties.

Soil types influence the characteristic of antibiotic resistance genes in greenhouse soil with long-term manure application.

The spread of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) has become an increasingly serious global public health issue. This study investigated the distribution characteristics and influencing factors of ARB and ARGs in greenhouse vegetable soils with long-term application of manure. Five typical ARGs, four heavy metal resistance genes (MRGs), and two mobile genetic elements (MGEs) were quantified by real-time quantitative polymerase chain reaction (qPCR). The amount of ARB in manure-improved soil greatly exceeded that in control soil, and the bacterial resistance rate decreased significantly with increases in antibiotic concentrations. In addition, the resistance rate of ARB to enrofloxacin (ENR) was lower than that of tylosin (TYL). Real-time qPCR results showed that long-term application of manure enhanced the relative abundance of ARGs in vegetable soils, and the content and proportion of quinolone resistance genes were higher than those of macrolide resistance genes. Redundancy analysis (RDA) showed that qepA and qnrS significantly correlated with total and available amounts of Cu and Zn, highlighting that certain heavy metals can influence persistence of ARGs. Integrase gene intI1 correlated significantly with the relative abundance of qepA, qnrS, and ermF, suggesting that intI1 played an important role in the horizontal transfer of ARGs. Furthermore, there was a weakly but not significantly positive correlation between specific detected MRGs and ARGs and MGEs. The results of this study enhance understanding the potential for increasing ARGs in manure-applied soil, assessing ecological risk and reducing the spread of ARGs.

Distribution of quinolone and macrolide resistance genes and their co-occurrence with heavy metal resistance genes in vegetable soils with long-term application of manure.

Livestock manure is often used as fertilizer in greenhouses, resulting in simultaneous enrichment of heavy metals and antibiotic resistance genes (ARGs) in soils. The soil-plant system is a non-negligible way to spread ARGs; however, the effects of lead (Pb) on the spread of ARGs and their driving factors in the greenhouse soil-plant system remain unclear. In this present study, the occurrence of ARGs in greenhouse soils and their spread into plants under Pb stress were studied. Overall, Pb promoted the accumulation of ARGs in root endophytes at 10, 50, and 100 mg/kg as well as in soils at 10 and 200 mg/kg, but reduced the total relative abundance of ARGs in leaf endophytes. Particularly, Pb increased the mobile genetic elements (MGEs) relative abundance and endophytic bacterial community diversity in roots, consistent with the change in the total relative abundance of ARGs. Network analysis revealed that bacterial community and MGEs may jointly affect the migration of ARGs in the soil-plant system of greenhouses. Overall, this study extended our knowledge of how Pb can promote the transmission of ARGs to plant roots from greenhouse soils receiving long-term manure applications, which must be considered when assessing the risk of ARGs to public health.

Spread and driving factors of antibiotic resistance genes in soil-plant system in long-term manured greenhouse under lead (Pb) stress.

As a new type of environmental pollutant, antibiotic resistance genes (ARGs) pose a huge challenge to global health. Horizontal gene transfer (HGT) represents an important route for the spread of ARGs. The widespread use of sulfamethazine (SM2) as a broad-spectrum bacteriostatic agent leads to high residual levels in the environment, thereby increasing the spread of ARGs. Therefore, we chose to study the effect of SM2 on the HGT of ARGs mediated by plasmid RP4 from Escherichia coli (E. coli) HB101 to E. coli NK5449 as well as its mechanism of action. The results showed that compared with the control group, SM2 at concentrations of 10 mg/L and 200 mg/L promoted the HGT of ARGs, but transfer frequency decreased at concentrations of 100 mg/L and 500 mg/L. The transfer frequency at 200 mg/L was 3.04 × 10, which was 1.34-fold of the control group. The mechanism of SM2 improving conjugation transfer is via enhancement of the mRNA expression of conjugation genes (trbBP, trfAP) and oxidative stress genes, inhibition of the mRNA expression of vertical transfer genes, up regulation of the outer membrane protein genes (ompC, ompA), promotion of the formation of cell pores, and improvement of the permeability of cell membrane to promote the conjugation transfer of plasmid RP4. The results of this study provide theoretical support for studying the spread of ARGs in the environment.

Effect of sulfamethazine on the horizontal transfer of plasmid-mediated antibiotic resistance genes and its mechanism of action.

Residual antibiotics (ABs) and heavy metals (HMs) are continuously released from soil, reflecting their intensive use and contamination of water and soil, posing an environmental problem of great concern. Relatively few studies exist of the functional diversity of soil microorganisms under the combined action of ABs and HMs. To address this deficiency, BIOLOG ECO microplates and the Integrated Biological Responses version 2 (IBRv2) method were used to comprehensively explore the effects of single and combined actions of copper (Cu) and enrofloxacin (ENR), oxytetracycline (OTC), and sulfadimidine (SM2) on the soil microbial community. The results showed that the high concentration (0.80 mmol/kg) compound group had a significant effect on average well color development (AWCD) and OTC showed a dose-response relationship. The results of IBRv2 analysis showed that the single treatment group of ENR or SM2 had a significant effect on soil microbial communities, and the IBRv2 of E1 was 5.432. Microbes under ENR, SM2, and Cu stress had more types of available carbon sources, and all treatment groups were significantly more enriched with microorganisms having D-mannitol and L-asparagine as carbon sources. This study confirms that the combined effects of ABs and HMs can inhibit or promote the function of soil microbial communities. In addition, this paper will provide new insights into IBRv2 as an effective method to evaluate the impacts of contaminants on soil health.

Lanjun Wang

Key Laboratory of Agricultural Environment in Universities of Shandong,
College of Resources and Environment,
Key Laboratory of Agricultural Environment in Universities of Shandong, College of Resources and Environment

shandong agricultural university

Determination of the Absorption, Translocation, and Distribution of Imidacloprid in Wheat

Lanjun Wang

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Key Laboratory of Agricultural Environment in Universities of Shandong,College of Resources and Environment,Key Laboratory of Agricultural Environment in Universities of Shandong, College of Resources and Environment

shandong agricultural university

Determination of the Absorption, Translocation, and Distribution of Imidacloprid in Wheat

Key Laboratory of Agricultural Environment in Universities of Shandong,
College of Resources and Environment,
Key Laboratory of Agricultural Environment in Universities of Shandong, College of Resources and Environment