Thiamethoxam dynamics in pepper plants: Deciphering deposition and dissipation pattern across diverse planting modes and regions.

To reduce the application dosage of thiamethoxam (TMX), we investigated the deposition and dissipation patterns in a pepper-planted ecosystem under different planting modes across four regions in China, namely Hainan (HN), Zhejiang (ZJ), Anhui (AH) and Hebei (HB). This study focused on the deposition and dissipation of TMX at concentrations of 63.00, 47.25, 31.50, 23.63 and 15.75 g a.i.hm-2. As the application dose increased, the deposition amount of TMX initially increased in the plants and cultivated soil, showing obvious geographic differences in four cultivation areas. Surprisingly, the initial amount of TMX deposited the pepper-cultivated greenhouse of ZJ and AH was 1.1-2.1-fold and 1.0-3.6-fold higher than that in the open field system at the same application dose, respectively. In pepper leaves, stems, fruits and soil, the dissipation exhibited rapid growth and then slowed. However, the residual concentration showed an increasing trend, followed by a subsequent decrease in the pepper roots. In different planting regions, the dissipation rate of TMX followed the order HN > ZJ > AH > HB in pepper plants and cultivated soil. In comparison to the open field, the total TMX retention rate in greenhouse was higher, indicating overall greater persistence in the greenhouse conditions. These findings reveal the deposition and dissipation characteristics of TMX within the pepper-field ecosystem, offering a significant contribution to the risk assessment of pesticides.

Metabolomics analysis of the metabolic effects of citric acid on Issatchenkia terricola WJL-G4.

In current research, yeast species Issatchenkia terricola WJL-G4 was shown to be capable of degrading citric acid, especially in the processing of fruit juice and wine. I. terricola WJL-G4 was able to use citric acid as a carbon source, but the metabolic effects of citric acid on yeast remained unclear. In this study, the metabolic effects of citric acid on I. terricola WJL-G4 were studied using liquid chromatography-mass spectrometry metabolomics technology, with glucose treatment as the control. Results showed that organic acid contents related to the extracellular tricarboxylic acid cycle (TCA) varied greatly. The metabolomics results indicated that I. terricola WJL-G4 might metabolize citric acid through the TCA pathway, and the glycolysis pathway might be inhibited; however, gluconeogenesis proceeded normally during citric acid treatment. Some fatty acids and phospholipids, along with the metabolic pathways of amino acids, vitamins, purines and nicotinamide in I. terricola WJL-G4 were also affected by the citric acid treatment. This work provided a theoretical basis for further study of the mechanism of yeast metabolism of citric acid.

Deposition and dissipation of difenoconazole in pepper and soil and its reduced application to control pepper anthracnose.

The initial deposition amount, dissipation dynamics, retention rate, and field control efficacy of difenoconazole in pepper-soil system were studied with different application dosages, planting regions and patterns. The initial deposition amount of difenoconazole under the same application dosage showed the following order: fruits < cultivated soils < lower stems < upper stems < lower leaves < upper leaves, open field < greenhouse, and Changjiang < Cixi < Hefei < Langfang, respectively, which increased with increasing application dosage. The dissipation rates in leaves, stems, fruits and cultivated soils exhibited an initially fast and then slow trend, while the retention rates displayed a tendency of first increasing and then stabilizing with increasing application dosages. After 7 d of difenoconazole application, the retention rates at five concentrations were 10.3%- 39.1%, and the field efficacy mostly reached the minimum effective dose. These results suggested that difenoconazole could be reduced by 25% based on the minimum recommended dose meeting the requirements of field control efficacy for controlling pepper anthracnose.

Resource Allocation in Multi-Carrier Multiplexed NOMA Cooperative System.

Non-orthogonal multiple access (NOMA) cooperative communication technology can combine the advantages of NOMA and cooperative communication, providing high spectrum efficiency and increasing user coverage for next-generation wireless systems. However, the research on NOMA cooperative communication technology is still in a preliminary stage and has mainly concentrated on the scenario of fewer users. This paper focuses on a user-centered NOMA collaboration system in an ultra-dense network, and it constructs a resource allocation optimization problem to meet the demands of each user. Then, this paper decomposes the optimization problem into two subproblems; one is the grouping match among multiple relays and users, and the other is jointly allocating power and subcarrier resources. Accordingly, a dynamic packet matching algorithm based on Gale-Shapley and an iterative algorithm based on the difference of convex functions programing are proposed. Compared with existing schemes, the proposed algorithms can improve system throughput while ensuring the quality of service of users.

Positive intervention of insoluble dietary fiber from defatted rice bran on hyperlipidemia in high fat diet fed rats.

Increasing dietary fiber intake is considered to be an effective way to prevent and relieve the diseases associated with high-income lifestyles. Compared with soluble dietary fiber, comprehensive evaluation about the effects of insoluble dietary fiber on hyperlipidemia is rarely studied. In the present study, the insoluble dietary fiber was extracted from defatted rice bran by enzymatic treatments (IDF-dRB), followed by investigation about the adsorption and antioxidant activities in vitro. Moreover, the alleviating effects of IDF-dRB on hyperlipidemia were evaluated and analyzed. As a result, IDF-dRB possessed good adsorption capacities of glucose and cholesterol, and also exhibited excellent properties in scavenging radicals. Furthermore, intervention with IDF-dRB significantly improved lipid and glucose metabolism and alleviated inflammation and oxidative stress in rats fed high-fat diet. It was also observed that IDF-dRB treatment could recover the decline in species of gut microbiota caused by high fat diet, increase the community richness, and modulate the metabolic function of gut microbiota. In conclusion, the results indicated that IDF-dRB could ameliorate hyperlipidemia from many aspects and offered some perspectives about the effects of diet intervention with insoluble dietary fiber. PRACTICAL APPLICATION: Rice bran and defatted rice bran are coproducts in the rice processing industry and potentially valuable for the preparation of insoluble dietary fiber. Here an insoluble dietary fiber IDF-dRB was extracted from defatted rice bran and showed good properties in improving lipid and glucose levels, alleviating inflammation and oxidative stress, and modulating gut microbiota in rats fed high-fat diet, suggesting the potential application in ameliorating hyperlipidemia.

Reduced bacterial network complexity in agricultural soils after application of the neonicotinoid insecticide thiamethoxam.

Pesticides may alter soil microbial community structure or diversity, but their impact on microbial co-occurrence patterns remains unclear. Here, the effect of the widely used neonicotinoid insecticide thiamethoxam on the bacterial community in five arable soils was deciphered using the 16S rRNA gene amplicon sequencing technique. The degradation half-life of thiamethoxam in nonsterilized soils was significantly lower than that in sterilized soils, suggesting a considerable contribution from biodegradation. Soil bacterial community diversity diminished in high concentration thiamethoxam treatment and its impact varied with treatment concentration and soil type. Bacterial co-occurrence network complexity significantly decreased after exposure to thiamethoxam. Under thiamethoxam stress, the relative changes in bacterial co-occurrence networks were closely related (the majority of p-values < 0.05) to the soil physicochemical properties, yet the diversity and dominant phyla were slightly related (the majority of p-values > 0.05). Additionally, three bacterial genera, Sphingomonas, Streptomyces, and Catenulispora, were identified to be relevant to the degradation of thiamethoxam in soils. This finding deciphers the succession of the bacterial community under thiamethoxam stress across multiple soils, and emphasizes the potential role of physicochemical properties in regulating the ecotoxicological effect of pesticides on the soil microbiome.

Exposure to fungicide difenoconazole reduces the soil bacterial community diversity and the co-occurrence network complexity.

Difenoconazole is a triazole fungicide that is widely used worldwide and has been frequently detected in agricultural soils, but its ecotoxicological effect on soil bacterial community remains unknown. Here, the degradation of difenoconazole and its effect on soil bacterial communities were investigated at three concentrations in five different agricultural soils. Difenoconazole degraded faster in non-sterilized soils than in sterilized soils, suggesting that biodegradation is a major contributor to the dissipation of difenoconazole in soils. Exposure to high concentrations of difenoconazole decreased the soil bacterial community diversity in most soils, and this influence was aggravated with the increasing concentration. The effect of difenoconazole on soil bacterial community diversity was also enhanced with the increasing content of organic matter and total nitrogen in soils. Moreover, difenoconazole exposure also reduced the soil bacterial community network complexity and exhibited a concentration-dependent characteristic. In addition, a core bacterial community (57 operational taxonomic units, OTUs) was identified, and some core OTUs were strongly linked to the degradation of difenoconazole in soils. It is concluded that high concentrations of difenoconazole may have a significant effect on the soil bacterial communities, and co-occurrence networks may improve the ecotoxicological risk assessment of fungicides on soil microbiome.

Deposition, dissipation, and minimum effective dosage of the fungicide carbendazim in the pepper-field ecosystem.

BACKGROUND: In order to reduce application dosage of carbendazim (CBD), the effects of different droplet sizes and application rate on initial deposition, retention rate, and field control efficacy of CBD in the pepper plant (Capsicum annuum L.) were studied under laboratory and field conditions. RESULTS: Based on eight types of nozzles at six concentrations of 646.8, 582.2, 517.5, 414.0, 310.5, and 258.7 g a.i./hm2 , the initial deposition amount of CBD in the pepper plant showed a first increased and then decreased trend with the increasing application dosages. The initial deposition amount of CBD in the pepper leaves and stems was highest when using the nozzle ST110-03 at 200 µm volume median diameter (VMD) and 350 L/hm2 application rate. HPLC-MS/MS analysis revealed that CBD was first converted to 2-aminobenzimidazole, which then transformed into benzimidazole and 2-hydroxybenzimidazole by deamination and hydroxylation, and ultimately mineralized to carbon dioxide and water via the cleavage of the imidazole ring in pepper plant. The dissipation rate of CBD was fruits > roots/stems > leaves > soils. After 7 days of application, the field efficacy of CBD at six concentrations on pepper anthracnose (Colletotrichum spp.) were 94.1%, 91.3%, 82.3%, 76.5%, 47.0%, and 41.2%, respectively. CONCLUSION: The results revealed the deposition and dissipation characteristics of CBD, and the minimum effective dosage on pepper anthracnose decreased to 80% of the minimum recommended dose in the open field pepper ecosystem. The study will contribute to the CBD reduction by improving its utilization rate in the pepper-field ecosystem. © 2019 Society of Chemical Industry.

Deposition, Distribution, Metabolism, and Reduced Application Dose of Thiamethoxam in a Pepper-Planted Ecosystem.

To decrease the application dose of thiamethoxam (TMX) to control the pepper whitefly (Bemisia tabaci Q), the deposition, dissipation, metabolism, and field efficacy of TMX were investigated in a pepper (Capsicum annuum var. grossum)-planted ecosystem using eight types of nozzles at six concentrations (56.25, 41.25, 26.25, 21.0, 15.75, and 10.5 g a.i./hm2). The initial deposition amount of TMX in the pepper plant first increased and then decreased with increasing application dose. The optimum spray conditions of TMX were found to be a droplet size of 200 µm volume median diameter and a spray volume of 350 L/hm2. Moreover, three metabolites, TMX-dm, clothianidin (CLO), and C5H8O2N3SCl, were detected in the pepper-planted system. The dissipation rate of TMX in the pepper-field ecosystem was leaves > stems > fruits > roots > soils. The results revealed the deposition and fate of TMX in the pepper-field ecosystem, and the application dose could be reduced by 20% based on the minimum recommended dose for controlling pepper whitefly.

Exploring microbial community structure and biological function in manured soil during ten repeated treatments with chlortetracycline and ciprofloxacin.

The changes of enzyme activities, microbial community structure and function, and the diversity and resistance level of antibiotic-resistant bacteria (ARB) were studied in soil during ten repeated treatments with chlortetracycline (CTC) and/or ciprofloxacin (CIP) together with organic manure (OM) under laboratory conditions. The activities of neutral phosphatase (NPA) and catalase (CAT) displayed the suppression-recovery-stimulation trend in the OM&CTC treatment but the stimulation trend in the OM&CTC&CIP treatment. The NPA was stimulated but the CAT was little affected in the OM&CIP treatment. Soil microbial functional diversity displayed the suppression-recovery-stimulation trend in the OM&CTC and OM&CTC&CIP treatments and the stimulation-suppression trend in the OM&CIP treatment with the treatment frequency. Metagenomic analysis showed that the relative abundances of Actinobacteria and Firmicutes in the antibiotic treatment significantly increased by 0.5-235.6%, but that of Proteobacteria decreased by 0.2-27.3% compared to the control with the treatment frequency. Furthermore, the relative abundances of dominant bacterial genera including Streptomyces, Actinomadura, Mycobacterium, and Streptococcus in the antibiotic treatment significantly increased by 1.1-10433.3% compared to the control. Meanwhile, repeated antibiotic treatments induced a significant increase in the diversity and resistance level of ARB isolates, especially in the OM&CTC treatment. It is concluded that repeated treatments with CTC and/or CIP can alter enzyme activities, microbial community structure and function, and increase the diversity and resistance level of ARB isolates.

Adsorption and Desorption of Carbendazim and Thiamethoxam in Five Different Agricultural Soils.

The adsorption and desorption behaviors of carbendazim (CBD) and thiamethoxam (TMX) were systematically studied in five different agricultural soils. The adsorption and desorption isotherms of CBD and TMX in the five different soils were fitted well by the Freundlich model. The Freundlich adsorption coefficient (Kfads) and Freundlich desorption coefficient (Kfdes) of CBD in the five different soils were 1.46-19.53 and 1.81-3.33, respectively. The corresponding values of TMX were 1.19-4.03 and 2.07-6.45, respectively. The adsorption affinity and desorption ability of the five different soils for CBD and TMX depended mainly on soil organic matter content (OMC) and cation exchange capacity (CEC). Desorption hysteresis occurred in the desorption process of CBD and TMX in the five different agricultural soils, especially for TMX. It is concluded that the adsorption-desorption ability of CBD was much higher than that of TMX in the five different agricultural soils, which was attributed to soil OMC and CEC.

Exploring bacterial communities and biodegradation genes in activated sludge from pesticide wastewater treatment plants via metagenomic analysis.

Activated sludge (AS) has been regarded as the main driver in the removal of organic pollutants such as pesticides due to a high diversity and abundance of microorganisms. However, little is known about the biodegradation genes (BDGs) and pesticide degradation genes (PDGs) harbored in the AS from wastewater treatment plants (WWTPs). In this study, we explored the bacterial communities and BDGs/PDGs in the AS from five WWTPs affiliated with pesticide factories across four consecutive seasons based on high-throughput sequencing. The AS in pesticide WWTPs exhibited unique bacterial taxa at the genus level. Furthermore, a total of 17 BDGs and 68 PDGs were explored with a corresponding average relative abundance of 0.002-0.046% and 2.078-7.143% in each AS sample, respectively, and some BDGs/PDGs clusters were also identified in the AS. The bacterial communities and BDGs/PDGs were season-dependent, and the total variations of 50.4% and 76.8% were jointly explained by environmental variables (pesticide types, wastewater characteristics, and temperature). In addition, network analysis and distribution patterns suggested that the potential hosts of BDGs/PDGs were Thauera, Stenotrophomonas, Mycobacterium, Hyphomicrobium, Allochromatium, Ralstonia, and Dechloromonas. Our findings demonstrated the linkages of bacterial communities and BDGs/PDGs in the AS, and depended on the seasons and the pesticide wastewater characteristics.

Biodegradability and ecological safety assessment of Stenotrophomonas sp. DDT-1 in the DDT-contaminated soil.

The biodegradability and ecological safety assessment of the previously isolated DDT-degrading bacterial strain Stenotrophomonas sp. DDT-1 were investigated in the DDT-contaminated soil under laboratory and field conditions. Under laboratory conditions, the degradation rates of fresh p,p'-DDT in soil were enhanced by 2.0-3.0-fold with the introduction of the strain DDT-1 compared to those of the control treatments. A similar enhancement in the dissipation of DDTs (p,p'-DDT, p,p'-DDE, p,p'-DDD, and o,p'-DDT) in the aged DDT-contaminated field plot soils resulted from the inoculation with this strain. Meanwhile, the degradation rates of DDTs increased by 2.9-5.5- and 2.8-7.6-fold in the inoculated greenhouse and open field soils, respectively, after field demonstration application of strain DDT-1 preparation. Moreover, no significant differences in the soil enzyme activity, microbial functional diversity, and bacterial community structure were observed between the inoculated and un-inoculated field soils, but several soil microbial genera exhibited some fluctuations in abundance. It is concluded that strain DDT-1 could accelerate the removal of DDTs residues in field soils, and furthermore, its inoculation was ecologically safe.

Repeated treatments of ciprofloxacin and kresoxim-methyl alter their dissipation rates, biological function and increase antibiotic resistance in manured soil.

The dissipation of ciprofloxacin (CIP, 1.0 and 10.0mg/kg) and kresoxim-methyl (KM, 1.0 and 2.0mg/kg) in manure-amended soil, the variations in soil enzyme activities and microbial functional diversities, and CIP-induced bacterial community tolerances were studied using a chromatographic analysis, enzyme colorimetric and titration analyses, and the BIOLOG EcoPlate method. Three successive treatments of individual and combined samples of CIP and KM at low and high concentrations were performed at 60d intervals. The dissipation half-life of CIP increased, but that of KM decreased in manured soil with treatment frequency; furthermore, the combined treatment altered the dissipation rates of CIP and KM. A stronger inhibitory effect on the activities of soil neutral phosphatase and urease was observed in the individual KM treatment than in the individual CIP treatment. A similar inhibitory trend was also found in soil neutral phosphatase activity in the combined treatment at high concentration compared to that at low concentration, but the activity of soil catalase was enhanced in the early stages of the KM or CIP treatments. Meanwhile, the inhibitory trend on the overall activity and functional diversity of soil microorganisms was observed in the individual KM or CIP treatment, and the combined treatment exerted a greater suppression effect than that in the individual treatment. Bacterial community resistance to CIP increased significantly with increasing treatment frequency and concentration, and furthermore antibiotic resistance developed faster in the combined treatment than in the individual treatment. It was concluded that the repeated treatments of CIP and KM could alter their dissipation rates and soil enzyme activities, suppress microbial functional diversity, and increase bacterial community resistance to CIP in manured soil.