Soil type and moisture content alter soil microbial responses to manure from cattle administered antibiotics

Certain soil fungi impact the biosynthesis of amylose in maize when manure is used instead of chemical fertilizer at equal levels of nitrogen

The protracted and immoderate utilization of chemical fertilizers has been detrimental to the composition of fungi in the soil and quality of crops. To ameliorate the adverse effects, a 6-year positioning experiment was undertaken to investigate the impact of substituting 0 % (CF), 25 % (M25), 50 % (M50), 75 % (M75), and 100 % (M100) of 225 kg ha-1 chemical fertilizer nitrogen with manure nitrogen on both soil fungi and maize quality. This study showed that the expansion of Aspergillus heterocaryoticus, Xerochrysium dermatitidis, and Aspergillus penicillioides contributed to heightened levels of amylose and soluble sugars. The proliferation of Botryotrichum domesticum impeded the biosynthesis of amylose. Enhanced abundances of Erysiphe paeoniae and Fusarium asiaticum hindered the biosynthesis of soluble sugar, whereas the increase in Aspergillus flavus, Monascus pilosus, Xerochrysium xerophilum, and Wickerhamomyces anomalus increased the biosynthesis of soluble sugars. Sordariomycetes, Dothideomycetes, and Eurotiomycetes were the predominant classes. M50 significantly increased the relative abundance of populations of fungal parasites by 100.03 % and 219.82 % compared to CF and M00, respectively. Venturiales was the singular order of fungi exclusive to CF. Trichothecium roseum, Papiliotrema flavescens, and Paraisaria phuwiangensis emerged as distinguishing biomarkers for CF, M25, and M75, respectively. Papiliotrema flavescens could be utilized in the classification of samples.

Antibiotic sorption onto MPs in terrestrial environment: a critical review of the transport, bioaccumulation, ecotoxicological effects and prospects

Microplastics (MPs) and antibiotics are prevalent contaminants in terrestrial environment. MPs possess the ability to absorb antibiotics, resulting in the formation of complex pollutants. While the accumulation and fate of MPs and antibiotics in marine ecosystems have been extensively studied, their combined pollution behavior in terrestrial environments remains relatively underexplored. This paper describes the sources, migration, and compound pollution of MPs and antibiotics in soil. It reviews the mechanisms of compound toxicity associated with antibiotics and MPs, combining different biological classifications. Moreover, we highlight the factors that influence the effects of MPs as vectors and the critical elements driving the spread of antibiotic resistance genes (ARGs). These information suggests the potential mitigation measures for MPs contamination from different perspectives to reduce the impact of ARGs-carrying MPs on human health, specifically through transmission via plants, microbes, or terrestrial vertebrates. Finally, we identify gaps in scientific knowledge regarding the interaction between MPs and antibiotics in soil environments, including the need for standardized research methods, multi-dimensional studies on complex ecological effects, and more comprehensive risk assessments of other pollutants on human health. In summary, this paper provides foundational information for assessing their combined toxicity, offers insights into the distribution of these emerging pollutants in soil, and contributes to a better understanding of the environmental impact of these contaminants.

Trends in Escherichia coli and Klebsiella pneumoniae Urinary Tract Infections and Antibiotic Resistance over a 5-Year Period in Southeastern Gabon

Background: Urinary tract infections (UTIs) are a substantial global health concern, exacerbated by the widespread use of antibiotics and leading to the development of multidrug-resistant strains. The aim of this study was to analyze the temporal patterns of Escherichia coli and Klebsiella pneumoniae UTIs and antibiotic resistance, taking into account various sociodemographic, clinical, and climatic factors within the study population. Methods: A total of 3026 urine samples from patients of all ages were analyzed over a period of five years by standard microbiological methods. Climatic data for the study area were also collected. Univariate and multivariate logistic regression analyses were performed to measure the impact of sociodemographic, clinical and climatic parameters on the occurrence of UTIs. Results: The study showed a 31.4% prevalence of UTIs among the population. Notably, there was a significant increase in pyelonephritis between 2019 and 2023 (p < 0.01). Furthermore, a significant association was found between cystitis and the long dry season, as well as the short rainy season. Furthermore, Escherichia coli and Klebsiella pneumoniae exhibited resistance to beta-lactams, quinolones, and co-trimoxazole. The resistance of Escherichia coli isolated from cystitis to nitrofurantoin showed a significant increase over the years (p < 0.04). Principal component analysis (PCA) suggested that humidity may play a role in the emergence of multidrug-resistant strains of Escherichia coli and Klebsiella pneumoniae. Conclusions: UTIs show variability according to various sociodemographic, clinical, and climatic factors, with a higher risk of complications seen in individuals aged ≤ 17 years. It is important to note that cases of pyelonephritis have been increasing over time, with a noticeable seasonal variation. This study suggests that humidity may play a role in promoting antibiotic multidrug resistance in Escherichia coli and Klebsiella pneumoniae.

Culture-based and molecular investigation of antibiotic and metal resistance in a semi-arid agricultural soil repeatedly amended with urban sewage sludge

Unsustainable agricultural intensification and climate change effects have caused chronic soil depletion in most arid and semi-arid croplands. As such, the land application of urban sewage sludge (USS) has been regulated in several countries as an alternative soil conditioner with recycling benefits. However, the risks of multi-contamination have made its agricultural reuse debatable. Accordingly, this study explored the long-term the impact of repetitive USS applications with increasing rates (0, 40, 80, and 120 t ha-1 year-1) on a sandy soil properties. A special focus was on the spread of antibiotic-resistant bacteria, metal-resistant bacteria and corresponding resistance genes in soil (ARB, MRB, ARGs and MRGs, respectively). The outcomes showed a dose-dependent variation of different soil parameters including the increase of heavy metal content and total heterotrophic bacteria (THB) up to the highest sludge application rate. Besides, the two last sludge lots applied in fall 2019 and 2020 contained cultivable ARB for all addressed antibiotics at much higher counts than in corresponding treated soils. Interestingly, the average index of antibiotic resistance (ARB/THB) increased in the USS used in fall 2020 compared to 2019 (from 6.2% to 9.4%). This indicates that factors such as fluctuations in wastewater quality, treatments operations, and extensive antibiotic use following the outbreak of the COVID-19 pandemic in early 2020 could have caused this variation. The molecular assessment of bacterial resistance resulted in the identification of three ARGs (mefA, sul1 and sul2), one MRG (czcA) and one integron (intI1). This might have implications on resistance co-selection, which can pose a threat to human health via contaminated crops.

Responses of soil antibiotic resistance genes to the decrease in grain size of sediment discharged into Dongting Lake, China

Sediment or soil in wetlands is regarded as an important sink of antibiotic resistance genes (ARGs). However, there are no studies on the effects of sediment changes (which caused changes in soil texture) on soil ARGs in wetland. Here, we collected topsoil samples from 12 study sites that were deposited in early (prior to the 1970s) or recent years to reveal the responses of soil ARGs to the decrease in grain size of sediment discharged into Dongting Lake. The results indicated that it caused significant increases in clay content, soil organic matter (SOM), moisture, and bacterial abundance. The absolute abundance of 38 % ARG subtypes, 62 % ARG types, and the total ARG concentrations showed a significant increase. The composition of ARG profiles also showed significant changes. For mobile genetic elements (MGEs), the levels of plasmid, insertional, and transposase were significantly elevated. Notably, clay content, moisture, SOM, and bacterial abundance presented very strong positive correlation with most ARG and total ARG abundance. The contributions of physicochemical characteristics and bacterial abundance to ARG variations were ranked as follows: 16S rRNA > SOM > moisture > pH > soil texture (clay, sand and silt) > nitrate nitrogen > ammonium nitrogen. Bacterial abundance, SOM, moisture, and soil texture were the primary environmental parameters contributing to the soil ARG variations in this research. These changes of ARGs may pose risks to ecosystems and public health.

Does Bidens pilosa L. Affect Carbon and Nitrogen Contents, Enzymatic Activities, and Bacterial Communities in Soil Treated with Different Forms of Nitrogen Deposition?

The deposition of nitrogen in soil may be influenced by the presence of different nitrogen components, which may affect the accessibility of soil nitrogen and invasive plant-soil microbe interactions. This, in turn, may alter the success of invasive plants. This study aimed to clarify the influences of the invasive plant Bidens pilosa L. on the physicochemical properties, carbon and nitrogen contents, enzymatic activities, and bacterial communities in soil in comparison to the native plant Pterocypsela laciniata (Houtt.) Shih treated with simulated nitrogen deposition at 5 g nitrogen m-2 yr-1 in four forms (nitrate, ammonium, urea, and mixed nitrogen). Monocultural B. pilosa resulted in a notable increase in soil pH but a substantial decrease in the moisture, electrical conductivity, ammonium content, and the activities of polyphenol oxidase, β-xylosidase, FDA hydrolase, and sucrase in soil in comparison to the control. Co-cultivating B. pilosa and P. laciniata resulted in a notable increase in total soil organic carbon content in comparison to the control. Monocultural B. pilosa resulted in a notable decrease in soil bacterial alpha diversity in comparison to monocultural P. laciniata. Soil FDA hydrolase activity and soil bacterial alpha diversity, especially the indices of Shannon's diversity, Simpson's dominance, and Pielou's evenness, exhibited a notable decline under co-cultivated B. pilosa and P. laciniata treated with nitrate in comparison to those treated with ammonium, urea, and mixed nitrogen.