Participatory modelling of scenarios to restore nitrogen cycles in a nutrient-saturated area.

This paper aims to find socially acceptable solutions of circularity as measure to reduce nitrogen (N) losses and prevent environmental damage by combining participatory modelling and scenario Substance Flow Analyses (SFA). A local perspective was taken on the agro-food-waste system in the animal production-dominated German district Cleves. Three scenarios were programmed as Monte Carlo simulation of SFA with stakeholder input regarding crop allocation, livestock composition, livestock reduction, and manure allocation following the elimination of feed imports. The three scenarios either utilized the unaltered stakeholder input (PS), altered crop allocation to satisfy the demand for feed (CBS), or adjusted the livestock numbers to match the locally available feed (LBS). In the reference year (2020) agricultural losses amounted to 68 kg N year-1 ha-1 agricultural land and 116 kg N in feed was imported year-1 ha-1 agricultural land. In the PS feed import elimination led to deficits in feed availability. The LBS showed the biggest reduction of agricultural N losses and improved N use efficiency (+6 %), however agricultural losses were still high (50 kg N year-1 ha-1 agricultural land). The results show a limited effect of feed import elimination on N losses if no further measures are taken, such as reduced consumption of animal-based products. Further, the study shows that it is important to improve stakeholders' knowledge about approaches to circular agro-food-waste systems. The discrepancy between stakeholder visions and N circularity provide policy makers with the recommendation to improve stakeholders' visions of a circular agro-food-waste system.

Functions of elements in soil microorganisms.

The soil microbial community fulfils various functions, such as nutrient cycling and carbon (C) sequestration, therefore contributing to maintenance of soil fertility and mitigation of global warming. In this context, a major focus of research has been on C, nitrogen (N) and phosphorus (P) cycling. However, from aquatic and other environments, it is well known that other elements beyond C, N, and P are essential for microbial functioning. Nonetheless, for soil microorganisms this knowledge has not yet been synthesised. To gain a better mechanistic understanding of microbial processes in soil systems, we aimed at summarising the current knowledge on the function of a range of essential or beneficial elements, which may affect the efficiency of microbial processes in soil. This knowledge is discussed in the context of microbial driven nutrient and C cycling. Our findings may support future investigations and data evaluation, where other elements than C, N, and P affect microbial processes.

Distinct Resistomes and Microbial Communities of Soils, Wastewater Treatment Plants and Households Suggest Development of Antibiotic Resistances Due to Distinct Environmental Conditions in Each Environment.

The use of antibiotics in humans and animals results in a release of excess antibiotic residues into the environment through wastewaters and insufficient removal in wastewater treatment plants (WWTP), leading to increasing numbers of bacteria enriched in antibiotic resistance genes (ARG). However, the potential transfer of ARG and their host bacteria between different environments remains largely unexplored. Since many factors need to be fulfilled for a transfer between different environments, we hypothesized that antibiotic resistance (ABR) is less frequently transferred between environments in the same geographical region but rather develops and clusters in each distinct environment, leading to characteristic metagenome patterns in samples of different environments. We sampled agricultural soils, a WWTP and private households and performed metagenomic analyses to evaluate differences and potential overlaps in bacterial communities and resistomes of different environments. Wastewater revealed significantly higher richness of ARG (n = 40) and mobile genetic elements (n = 52) than soil and household samples. Bacterial communities differed between the environments and antibiotic resistance factors clustered distinctly. Overall, only few overlaps of ARG between the environments were observed, leading to the conclusion that ABR predominantly develops in individual environments as caused by environmental filtering for ARG, while a transfer between different environments is less likely.

Evidence of considerable C and N transfer from peas to cereals via direct root contact but not via mycorrhiza.

Intercropping of legumes and cereals is an important management method for improving yield stability, especially in organic farming systems. However, knowledge is restricted on the relevance of different nutrient transfer pathways. The objective of the study was to quantify nitrogen (N) and carbon (C) transfer from peas to triticale by (1) direct root contact (= R), (2) arbuscular mycorrhizal fungi (AMF; = A), and (3) diffusion (= D). Pea (Pisum sativum cv. Frisson and P2) and triticale (Triticum × Secale cv. Benetto) plants as intercrop were grown for 105 days. Treatment ADR enabled all transfer paths between the two crops. Treatment AD with root exclusion enabled AMF and diffusion transfer between peas and triticale. Treatment A with a diffusion gap barrier only allowed AMF transfer. Pea plants were labelled every 14 days with a 13C glucose and 15N urea solution, using the cotton wick technique. Direct root contact resulted in the highest pea rhizodeposition and thus the largest absolute amounts of N and C transfer to triticale. Root exclusion generally changed composition of rhizodeposits from fine root residues towards root exudates. Pea plant-N consisted of 17% N derived from rhizodeposition (NdfR) in treatment ADR but only 8% in the treatments AD and A, independently of pea variety, whereas pea plant-C consisted of 13% C derived from rhizodeposition (CdfR), without pea variety and transfer path treatment effects. Averaging all transfer path treatments, 6.7% of NdfR and 2.7% of CdfR was transferred from Frisson and P2 to triticale plants. Approximately 90% of this NdfR was transferred by direct root contact from Frisson to triticale and only 10% by AMF, whereas only 55% of CdfR was transferred to triticale by direct root contact, 40% by AMF and 5% by diffusion. Similar percentages were transferred from mutant P2 to triticale. Root exclusion generally changed RD composition from fine root residues towards root exudates.

The Household Resistome: Frequency of ß-Lactamases, Class 1 Integrons, and Antibiotic-Resistant Bacteria in the Domestic Environment and Their Reduction during Automated Dishwashing and Laundering.

Households provide a habitat for bacteria originating from humans, animals, foods, contaminated clothes, or other sources. Thus, bacteria carrying antibiotic resistance genes (ARGs) may be introduced via household members, animals, or the water supply from external habitats into private households and vice versa. Since data on antibiotic resistance (ABR) in the domestic environment are limited, this study aimed to determine the abundance of ß-lactamase, mobile colistin resistance, and class 1 integron genes and the correlation of their presence and to characterize phenotypically resistant strains in 54 private households in Germany. Additionally, the persistence of antibiotic-resistant bacteria during automated dishwashing compared to that during laundering was assessed. Shower drains, washing machines, and dishwashers were sampled and analyzed using quantitative real-time PCR. Resistant strains were isolated, followed by identification and antibiotic susceptibility testing using a Vitek 2 system. The results showed a significantly higher relative ARG abundance of 0.2367 ARG copies/16S rRNA gene copies in shower drains than in dishwashers (0.1329 ARG copies/16S rRNA gene copies) and washing machines (0.0006 ARG copies/16S rRNA gene copies). blaCMY-2, blaACT/MIR, and blaOXA-48 were the most prevalent ARG, and intI1 occurred in 96.3% of the households, while no mcr genes were detected. Several ß-lactamase genes co-occurred, and the resistance of bacterial isolates correlated positively with genotypic resistance, with carbapenemase genes dominating across isolates. Antibiotic-resistant bacteria were significantly reduced during automated dishwashing as well as laundering tests and did not differ from susceptible strains. Overall, the domestic environment may represent a potential reservoir of ß-lactamase genes and ß-lactam-resistant bacteria, with shower drains being the dominant source of ABR.IMPORTANCE The abundance of antibiotic-resistant bacteria and ARGs is steadily increasing and has been comprehensively analyzed in natural environments, animals, foods, and wastewater treatment plants. In this respect, ß-lactams and colistin are of particular interest due to the emergence of multidrug-resistant Gram-negative bacteria. Despite the connection of private households to these environments, only a few studies have focused on the domestic environment so far. Therefore, the present study further investigated the occurrence of ARGs and antibiotic-resistant bacteria in shower drains, washing machines, and dishwashers. The analysis of the domestic environment as a potential reservoir of resistant bacteria is crucial to determine whether households contribute to the spread of ABR or may be a habitat where resistant bacteria from the natural environment, humans, food, or water are selected due to the use of detergents, antimicrobial products, and antibiotics. Furthermore, ABR could limit the options for the treatment of infections arising in the domestic environment.

Living in the plastic age - Different short-term microbial response to microplastics addition to arable soils with contrasting soil organic matter content and farm management legacy.

Microplastics (MPs) are an emerging pollutant found in many ecosystems including soils, where they may become toxic to organisms or alter their habitat. However, little is known about the influence of MPs on soil microorganisms and processes vital to ecosystem functioning in different soils. Therefore, our objective was to investigate the short-term effects of MPs pollution on soil microorganisms in two agricultural soils with contrasting soil organic matter content and microbial biomass as caused by farm management history (organic and conventional). Soils were amended with two kinds of raw MPs particles, low-density polyethylene (LDPE) and polypropylene (PP) in the size range of 200-630 µm at a rate of 1% w/w and incubated for 28 days. During incubation, microbial respiration was determined. After incubation, the microbial biomass carbon (C) and nitrogen (N), gene copy numbers of archaea, bacteria and fungi were quantified and extractions performed to gauge effects on C and N mineralisation. The results of this study showed no major detrimental effects of MPs on microbial activity. However, in particular PP reduced microbial biomass in both soils, with a stronger decline in the organic soil, showing lower resistance to MPs. Nevertheless, mineralisation processes remained on the same level, showing functional resistance of the microbial community to MPs addition in both soils. The microbial community composition was not significantly altered by MPs addition, even though fungi tended to decrease in the organic soil. Overall, management legacy had a stronger effect on soil microorganisms, with higher microbial biomass and activity in the organic soil. While this study does not answer whether MPs pollution has a negative impact on soil microorganisms, it highlights the need to consider potential interactive effects of environmental factors, land use and management with MPs on soil microbial communities and their functions.

Winter is coming - Impact of temperature on the variation of beta-lactamase and mcr genes in a wastewater treatment plant.

Wastewater treatment plants (WWTP) play a key role in the dissemination of antibiotic resistance and analyzing the abundance of antibiotic resistance genes (ARGs) and resistant bacteria is necessary to evaluate the risk of proliferation caused by WWTPs. Since few studies investigated the seasonal variation of antibiotic resistance, this study aimed to determine the abundance of beta-lactamase and mcr genes and to characterize phenotypic resistant strains in a WWTP in Germany over the seasons. Wastewater, sewage sludge and effluent samples were collected over a one year period and analyzed using quantitative real-time PCR. Resistant strains were isolated, followed by identification and antibiotic susceptibility testing using VITEK 2. The results show a significantly higher occurrence of nearly all investigated ARGs in the wastewater compared to sewage sludge and effluent. ARG abundance and temperature showed a negative correlation in wastewater and significant differences between ARG abundance during warmer and colder seasons were determined, indicating a seasonal effect. Co-occurrence of mcr-1 and carbapenemase genes in a multi-drug resistant Enterobacter cloacae and Escherichia coli producing extended-spectrum beta-lactamase (ESBL) was determined. To the best of our knowledge, this is the first detection of mcr-1, blaVIM and blaOXA-48 in an ESBL-producing E. coli. Although wastewater treatment reduced the abundance of ARGs and resistant strains, a dissemination into the river might be possible because carbapenemase-, CTX-M- and mcr-1-gene harboring strains were still present in the effluent.

Relationship between Remote Sensing Data, Plant Biomass and Soil Nitrogen Dynamics in Intensively Managed Grasslands under Controlled Conditions.

The sustainable use of grasslands in intensive farming systems aims to optimize nitrogen (N) inputs to increase crop yields and decrease harmful losses to the environment at the same time. To achieve this, simple optical sensors may provide a non-destructive, time- and cost-effective tool for estimating plant biomass in the field, considering spatial and temporal variability. However, the plant growth and related N uptake is affected by the available N in the soil, and therefore, N mineralization and N losses. These soil N dynamics and N losses are affected by the N input and environmental conditions, and cannot easily be determined non-destructively. Therefore, the question arises: whether a relationship can be depicted between N fertilizer levels, plant biomass and N dynamics as indicated by nitrous oxide (N2O) losses and inorganic N levels. We conducted a standardized greenhouse experiment to explore the potential of spectral measurements for analyzing yield response, N mineralization and N2O emissions in a permanent grassland. Ryegrass was subjected to four mineral fertilizer input levels over 100 days (four harvests) under controlled environmental conditions. The soil temperature and moisture content were automatically monitored, and the emission rates of N2O and carbon dioxide (CO2) were detected frequently. Spectral measurements of the swards were performed directly before harvesting. The normalized difference vegetation index (NDVI) and simple ratio (SR) were moderately correlated with an increasing biomass as affected by fertilization level. Furthermore, we found a non-linear response of increasing N2O emissions to elevated fertilizer levels. Moreover, inorganic N and extractable organic N levels at the end of the experiment tended to increase with the increasing N fertilizer addition. However, microbial biomass C and CO2 efflux showed no significant differences among fertilizer treatments, reflecting no substantial changes in the soil biological pool size and the extent of the C mineralization. Neither the NDVI nor SR, nor the plant biomass, were related to cumulative N2O emissions or inorganic N at harvesting. Our results verify the usefulness of optical sensors for biomass detection, and show the difficulty in linking spectral measurements of plant traits to N processes in the soil, despite that the latter affects the former.

Dose-dependent reactions of Aporrectodea caliginosa to perfluorooctanoic acid and perfluorooctanesulfonic acid in soil.

As a consequence of their widespread use, e.g. as protective coatings for fabrics, and their resistance to thermal and biological breakdown, perfluorinated compounds are increasingly found in the environment, but little is known about their ecotoxicological properties. A 40-day microcosm experiment was carried out to examine the effects of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) on the endogeic geophagus earthworm Aporrectodea caliginosa, its survival and feeding on soil organic C and microbial biomass C. Three levels of concentration (1, 100, and 500 mg kg(-1)) were chosen. The lowest represented the maximum found in sediments and soils and the other two are extreme concentrations that might occur in pollution hotspots and that have been shown to poison organisms. Earthworms promoted the production of CO2 and decreased microbial biomass C in soil, regardless of the presence of PFOA or PFOS. Both compounds significantly decreased the surviving numbers and dry weight of earthworms at concentrations of 100 mg kg(-1). No earthworms survived at PFOA and PFOS concentrations of 500 mg kg(-1). At concentrations of 1 mg kg(-1), no negative effects were observed. The δ(13)C values of A. caliginosa did not differ between treatments. In contrast, the δ(15)N values were significantly increased after adding 1 mg kg(-1) of PFOA, reflecting elevated portions of soil-derived N in the earthworm tissue. In contrast, these portions of soil-derived N were lower in the earthworms after addition of 100 mg kg(-1) of PFOA and PFOS. In conclusion, extreme concentrations of PFOA and PFOS negatively affected endogeic A. caliginosa, whereas a concentration of 1 mg kg(-1) of PFOA and PFOS was related to an increased uptake of soil N by the earthworms.