Nanoscale zero-valent iron inhibits the horizontal gene transfer of antibiotic resistance genes in chicken manure compost

2021 ◽  
pp. 126883
Author(s):  
Xiuwen Qiu ◽  
Guixiang Zhou ◽  
Huijuan Wang
mBio ◽  
2015 ◽  
Vol 6 (5) ◽  
Author(s):  
María Getino ◽  
David J. Sanabria-Ríos ◽  
Raúl Fernández-López ◽  
Javier Campos-Gómez ◽  
José M. Sánchez-López ◽  
...  

ABSTRACT Bacterial conjugation constitutes a major horizontal gene transfer mechanism for the dissemination of antibiotic resistance genes among human pathogens. Antibiotic resistance spread could be halted or diminished by molecules that interfere with the conjugation process. In this work, synthetic 2-alkynoic fatty acids were identified as a novel class of conjugation inhibitors. Their chemical properties were investigated by using the prototype 2-hexadecynoic acid and its derivatives. Essential features of effective inhibitors were the carboxylic group, an optimal long aliphatic chain of 16 carbon atoms, and one unsaturation. Chemical modification of these groups led to inactive or less-active derivatives. Conjugation inhibitors were found to act on the donor cell, affecting a wide number of pathogenic bacterial hosts, including Escherichia, Salmonella, Pseudomonas, and Acinetobacter spp. Conjugation inhibitors were active in inhibiting transfer of IncF, IncW, and IncH plasmids, moderately active against IncI, IncL/M, and IncX plasmids, and inactive against IncP and IncN plasmids. Importantly, the use of 2-hexadecynoic acid avoided the spread of a derepressed IncF plasmid into a recipient population, demonstrating the feasibility of abolishing the dissemination of antimicrobial resistances by blocking bacterial conjugation. IMPORTANCE Diseases caused by multidrug-resistant bacteria are taking an important toll with respect to human morbidity and mortality. The most relevant antibiotic resistance genes come to human pathogens carried by plasmids, mainly using conjugation as a transmission mechanism. Here, we identified and characterized a series of compounds that were active against several plasmid groups of clinical relevance, in a wide variety of bacterial hosts. These inhibitors might be used for fighting antibiotic-resistance dissemination by inhibiting conjugation. Potential inhibitors could be used in specific settings (e.g., farm, fish factory, or even clinical settings) to investigate their effect in the eradication of undesired resistances.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Natalia B. Naumova ◽  
Helen N. Ruchko ◽  
Oleg A. Savenkov ◽  
Valentina I. Pleshakova

The aim of the study. The aim of the study was to review publication about microbiome of chicken manure, chicken manure compost, as well as soil and crop microbiome after compost addition to soil as a fertilizer. Methodology. A search in the bibliographical data bases PubMed and elibrary.ru was performed using the keywords pertaining to the topic of the article. Main results. The results about the chicken manure microbiome, obtained by high throughput sequencing, showed that the chicken gut microbiome is dominated by bacteria of the Firmicutes and Bacteroidetes phyla; some regional chicken populations were found to have Clostridium, Lactobacillus, Eubacterium, Bacteroides, Escherichia coli, Prevotella, Selenomonas, Streptococcus, Megasphaera, Fusobacterium и Bifidobacterium as the main representatives of the gut microbiome. However, chicken manure can contain bacteria with antibiotic resistance genes, as antibiotics are increasingly used in the poultry industry to stimulate production. In general manure composting can be regarded as environmentally safe method for transforming various organic wastes into organic fertilizers. As increasing output of the poultry industry, which inevitably includes manure, increased the interest to its composting, and recent years have seen unprecedented number of research, dealing with various details of manure composting, such as duration, hydrothermal conditions, added bulking materials, microbiological preparations, abundance of the antibiotic resistance genes, and so on. However, the studies of soil and crop microbiome after soil fertilization with chicken manure compost have so far been rather scarce, resulting in ambiguous conclusions, i.e. about positive or no effect of the compost addition. The effect is determined by species, breed, age, rearing and manure composting technology, as well as by crop and its cultivar, agricultural practices and soil specifics. Conclusions. Chicken manure contains taxonomically diverse microbiome that can be changed during composting. Microbiota of chicken manure and its compost with their great microbial species richness can contain bacteria, carrying antibiotic resistance genes. Dispersal of such components of the compost resistome in environment via compost addition to agricultural soils should be regarded as a growing biological hazard, threatening the efficient use of antibiotics for treating bacterial infections in in veterinary and medicine. Therefore increasing poultry production urges for assessing the risks and evaluating the scope of the threat, as well as estimating and establishing permissible limits of pathomicrobiotic load of the poultry litter manure and compost, using up-to-date metagenomic techniques. The greatest concern is about spreading antibiotic resistance genes into the marketable crop components, consumed raw; consequently, alongside with studying microbiota of the compost-receiving agricultural soil as a source of dust, microbiome research should be also focused crop phytobiome where crops are produced under addition of composts, obtained with manure of the antibiotic-treated poultry during industrial production.


2021 ◽  
Author(s):  
Heather A. Kittredge ◽  
Kevin M. Dougherty ◽  
Sarah E. Evans

AbstractAntibiotic resistance genes (ARGs) are ubiquitous in the environment and pose a serious risk to human and veterinary health. While many studies focus on the spread of live antibiotic resistant bacteria throughout the environment, it is unclear whether extracellular ARGs from dead cells can transfer to live bacteria to facilitate the evolution of antibiotic resistance in nature. Here, we inoculate antibiotic-free soil with extracellular ARGs (eARGs) from dead Pseudeononas stutzeri cells and track the evolution of antibiotic resistance via natural transformation – a mechanism of horizontal gene transfer involving the genomic integration of eARGs. We find that transformation facilitates the rapid evolution of antibiotic resistance even when eARGs occur at low concentrations (0.25 μg g-1 soil). However, when eARGs are abundant, transformation increases substantially. The evolution of antibiotic resistance was high under soil moistures typical in terrestrial systems (5%-30% gravimetric water content) and was only inhibited at very high soil moistures (>30%). While eARGs transformed into live cells at a low frequency, exposure to a low dose of antibiotic allowed a small number of transformants to reach high abundances in laboratory populations, suggesting even rare transformation events pose a risk to human health. Overall, this work demonstrates that dead bacteria and their eARGs are an overlooked path to antibiotic resistance, and that disinfection alone is insufficient to stop the spread of antibiotic resistance. More generally, the spread of eARGs in antibiotic-free soil suggests that transformation allows genetic variants to establish at low frequencies in the absence of antibiotic selection.ImportanceOver the last decade, antibiotics in the environment have gained increasing attention because they can select for drug-resistant phenotypes that would have otherwise gone extinct. To counter this effect, bacterial populations exposed to antibiotics often undergo disinfection. However, the release of extracellular antibiotic resistance genes (eARGs) into the environment following disinfection can promote the transfer of eARGs through natural transformation. This phenomenon is well-documented in wastewater and drinking water, but yet to be investigated in soil. Our results directly demonstrate that eARGs from dead bacteria are an important, but often overlooked source of antibiotic resistance in soil. We conclude that disinfection alone is insufficient to prevent the spread of ARGs. Special caution should be taken in releasing antibiotics into the environment, even if there are no live antibiotic resistant bacteria in the community, as transformation allows DNA to maintain its biological activity past microbial death.


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