Project description:The spread of antibiotic resistance genes (ARG) into agricultural soils, products, and foods severely limits the use of organic fertilizers in agriculture. In this study, experimental land plots were fertilized, sown, and harvested for two consecutive agricultural cycles using either mineral or three types of organic fertilizers: sewage sludge, pig slurry, or composted organic fraction of municipal solid waste. The analysis of the relative abundances of more than 200,000 ASV (Amplicon Sequence Variants) allowed the identification of a small, but significant (<10%) overlap between soil and fertilizer microbiomes, particularly in soils sampled the same day of the harvest (post-harvest soils). Loads of clinically relevant ARG were significantly higher (up to 100 fold) in fertilized soils relative to the initial soil. The highest increases corresponded to post-harvest soils treated with organic fertilizers, and they correlated with the extend of the contribution of fertilizers to the soil microbiome. Edible products (lettuce and radish) showed low, but measurable loads of ARG (sul1 for lettuces and radish, tetM for lettuces). These loads were minimal in mineral fertilized soils, and strongly dependent on the type of fertilizer. We concluded that at least part of the observed increase on ARG loads in soils and foodstuffs were actual contributions from the fertilizer microbiomes. Thus, we propose that adequate waste management and good pharmacological and veterinarian practices may significantly reduce the potential health risk posed by the presence of ARG in agricultural soils and plant products.
Project description:Anaerobic digestion (AD) is a core technology in management of urban organic wastes, converting a fraction of the organic carbon to methane and the residual digestate, the biorest, have a great potential to become a major organic fertilizer for agricultural soils in the future. At the same time, mitigation of N2O-emissions from the agricultural soils is needed to reduce the climate forcing by food production. Our goal was therefore to enrich for N2O reducing bacteria in AD digestates prior to fertilization, and in this way provide an avenue for large-scale and low-cost cultivation of strongly N2O reducing bacteria which can be directly introduced to agricultural soils in large enough volumes to alter the fate of nitrogen in the soils. Gas kinetics and meta-omics (metagenomics and metaproteomics) analyses of the N2O enriched digestates identified populations of N2O respiring organisms that grew by harvesting fermentation intermediates of the methanogenic consortium.
Project description:The diversity and environmental distribution of the nosZ gene, which encodes the enzyme responsible for the consumption of nitrous oxide, was investigated in marine and terrestrial environments using a functional gene microarray. The microbial communities represented by the nosZ gene probes showed strong biogeographical separation, with communities from surface ocean waters and agricultural soils significantly different from each other and from those in oceanic oxygen minimum zones. Atypical nosZ genes, usually associated with incomplete denitrification pathways, were detected in all the environments, including surface ocean waters. The abundance of nosZ genes, as estimated by quantitative PCR, was highest in the agricultural soils and lowest in surface ocean waters.
Project description:Two-stage channels are a relatively new best management practice design used to treat nonpoint pollution. Soils collected from these channels in agricultural ditches were analyzed to elucidate the microbial functionality of the system.
2020-08-01 | GSE125810 | GEO
Project description:Studies of nitrifiers and anammox