Isolation, characterization, and genetic manipulation of cold-tolerant, manganese-oxidizing Pseudomonas sp. strains

Manganese-oxidizing bacteria (MnOB) produce Mn oxide minerals that can be used by humans for bioremediation, but the purpose for the bacterium is less clear. This study describes the isolation and characterization of cold-tolerant MnOB strains isolated from a compost pile in Morris, Minnesota, USA: Pseudomonas sp. MS-1 and DSV-1. The strains were preliminarily identified as members of species Pseudomonas psychrophila by 16S rRNA analysis and a multi-locus phylogenetic study using a database of 88 genomes from the Pseudomonas genus. However, the average nucleotide identity between these strains and the P. psychrophila sp. CF149 type strain was less than 93%. Thus, the two strains are members of a novel species that diverged from P. psychrophila. DSV-1 and MS-1 are cold tolerant; both grow at 4°C but faster at 24°C. Unlike the mesophilic MnOB P. putida GB-1, both strains are capable of robustly oxidizing Mn at low temperatures. Both DSV-1 and MS-1 genomes contain homologs of several Mn oxidation genes found in P. putida GB-1 (mnxG, mcoA, mnxS1, mnxS2, and mnxR). Random mutagenesis by transposon insertion was successfully performed in both strains and identified genes involved in Mn oxidation that were similar to those found in P. putida GB-1. Our results show that MnOB can be isolated from compost, supporting a role for Mn oxidation in plant waste degradation. The novel isolates Pseudomonas spp. DSV-1 and MS-1 both can oxidize Mn at low temperature and likely employ similar mechanisms and regulation as P. putida GB-1.IMPORTANCEBiogenic Mn oxides have high sorptive capacity and are strong oxidants. These two characteristics make these oxides and the microbes that make them attractive tools for the bioremediation of wastewater and contaminated environments. Identifying MnOB that can be used for bioremediation is an active area of research. As cold-tolerant MnOB, Pseudomonas sp. DSV-1 and MS-1 have the potential to expand the environmental conditions in which biogenic Mn oxide bioremediation can be performed. The similarity of these organisms to the well-characterized MnOB P. putida GB-1 and the ability to manipulate their genomes raise the possibility of modifying them to improve their bioremediation ability.

Determination and improvement of the quality of separately collected bio-waste from households

The recycling of bio-waste from households is an essential factor in achieving the recycling quotas for municipal waste laid down by the EU. A major problem is posed by impurities in the bio-waste collected, such as plastics, metals and glass. It is virtually impossible for compost producers to produce quality-assured compost from bio-waste with an impurity content of more than 3 wt%OS. The draft of the new Austrian Compost Ordinance stipulates a limit of 2 wt%OS of interfering substances in accepted bio-waste. A rapid measurement method has been developed and comprehensively validated for the immediate on-site checking of contaminant content at the bio-waste bin or in a vehicles. Data on the type and amount of impurities collected in the course of sorting analyses carried out over several years in 10 selected areas in Styria, Austria showed an average impurity content of 2.1 wt%OS. This impurity content can be considered representative for rural and urban communities in Austria. Among the interfering substances, plastics predominate, at 53%, of which pre-collection bags made of plastics form the highest proportion. A more detailed examination of pre-collection bags shows a higher proportion of use of biodegradable plastic bags, which have become more numerous in recent years in the more rural communities. In order to reduce mis-sorting, the effect of a wide variety of measures on citizens was tested in selected areas. Here, the distribution of paper bags as well as the threat of a cost increase due to special collections in combination with distribution of these bags were the methods with the greatest effect. Motivational letters and the threat of special collections, however, showed no significant result.

Digestate Improves Stinging Nettle (Urtica dioica) Growth and Fiber Production at a Chlor-Alkali Site

Marginal lands have been proposed to produce non-food crop biomass for energy or green materials. For this purpose, the selection, implementation, and growth optimization of plant species on such lands are key elements to investigate to achieve relevant plant yields. Stinging nettle (Urtica dioica) is a herbaceous perennial that grows spontaneously on contaminated lands and was described as suitable to produce fibers for material applications. Two mercury-contaminated soils from industrial wastelands with different properties (grassland soil and sediment landfill) were used in this study to assess the potential growth of stinging nettle in a greenhouse mesocosm experiment. Two organic amendments were studied for their impact on nettle growth. The solid digestate from organic food wastes significantly doubled plant biomass whereas the compost from green wastes had a lower impact. The highest doses of organic amendments significantly increased the number of fibers, which doubled following digestate application, while reducing leaf Hg concentration. Both amendments significantly improved soil respiration and enzymatic activities linked to the microbial biomass in the soil from the sediment landfill by the end of the experiment. In the context of a phytomanagement scenario, solid digestate would be a preferred amendment resource to improve nettle production on industrial wastelands.

The Use of Compost and Arbuscular Mycorrhizal Fungi and Their Combination to Improve Tomato Tolerance to Salt Stress

Salinity poses a significant challenge to tomato plant development and metabolism. This study explores the use of biostimulants as eco-friendly strategies to enhance tomato plant tolerance to salinity. Conducted in a greenhouse, the research focuses on the Solanum lycopersicum L. behavior under saline conditions. Tomato seeds were treated with arbuscular mycorrhizal fungi (AMF), compost, and their combination under both non-saline and saline conditions (0 and 150 mM NaCl). Plant height, number of flowers and fruits, shoot fresh weight, and root dry weight were negatively impacted by salt stress. The supplementation with compost affected the colonization of AMF, but the application of stress had no effect on this trait. However, the use of compost and AMF separately or in combination showed positive effects on the measured parameters. At the physiological level, compost played a beneficial role in increasing photosynthetic efficiency, whether or not plants were subjected to salinity. In addition, the application of these biostimulants led to an increase in nitrogen content in the plants, irrespective of the stress conditions. AMF and compost, applied alone or in combination, showed positive effects on photosynthetic pigment concentrations and protein content. Under salt stress, characterized by an increase in lipid peroxidation and H2O2 content, the application of these biostimulants succeeded in reducing both these parameters in affected plants through exhibiting an increase in antioxidant enzyme activity. In conclusion, incorporating compost, AMF, or their combined application emerges as a promising approach to alleviate the detrimental impacts of salt stress on both plant performances. These findings indicate optimistic possibilities for advancing sustainable and resilient agricultural practices.

Environmental Hot Spots and Resistance-Associated Application Practices for Azole-Resistant Aspergillus fumigatus, Denmark, 2020-2023

Azole-resistant Aspergillus fumigatus (ARAf) fungi have been found inconsistently in the environment in Denmark since 2010. During 2018-2020, nationwide surveillance of clinical A. fumigatus fungi reported environmental TR34/L98H or TR46/Y121F/T289A resistance mutations in 3.6% of isolates, prompting environmental sampling for ARAf and azole fungicides and investigation for selection of ARAf in field and microcosmos experiments. ARAf was ubiquitous (20% of 366 samples; 16% TR34/L98H- and 4% TR46/Y121F/T289A-related mechanisms), constituting 4.2% of 4,538 A. fumigatus isolates. The highest proportions were in flower- and compost-related samples but were not correlated with azole-fungicide application concentrations. Genotyping showed clustering of tandem repeat-related ARAf and overlaps with clinical isolates in Denmark. A. fumigatus fungi grew poorly in the field experiment with no postapplication change in ARAf proportions. However, in microcosmos experiments, a sustained complete (tebuconazole) or partial (prothioconazole) inhibition against wild-type A. fumigatus but not ARAf indicated that, under some conditions, azole fungicides may favor growth of ARAf in soil.

Mycovorax composti gen. nov., sp. nov., a member of the family Chitinophagaceae isolated from button mushroom compost

Two Gram-stain-negative, aerobic, rod-shaped, orange-coloured bacterial strains, designated strain C216T and strain M2295, were isolated from mature mushroom compost from composting facilities in Victoria and South Australia, Australia, respectively. External structures such as flagella or pili were not observed on the cells under scanning electron microscopy. Optimal growth was found to occur at 45 °C, at pH 7.25 and in the absence of NaCl on Emerson's 350 YpSs medium. The genome sequence of strain C216T was 3 342 126 bp long with a G+C content of 40.5 mol%. Functional analysis of the genome of strain C216T revealed genes encoding chitinolytic and hemi-cellulolytic functions, with 166 predicted genes associated with carbohydrate metabolism (8.9% of the predicted genes). These functions are important for survival in the mushroom compost environment, which is rich in hemicelluloses. No antibiotic resistance genes were found in the genome sequence. The major fatty acids of strain C216T were iso-C15 : 0 (56.7%), iso-C17 : 0 3-OH (15.6%), C16 : 1  ω7c/iso-C15 : 0 2-OH (7.3%) and iso-C15 : 1 G (6.1%). The only respiratory quinone was MK-7. The major polar lipid of strain C216T was phosphatidylethanolamine, but three unidentified phospholipids, four unidentified aminophospholipids/aminolipids and one unidentified glycolipid were also detected. Phylogenetic analysis based on proteins encoded by the core genome (bac120, 120 conserved bacterial genes) showed that strain C216T forms a distinct lineage in the family Chitinophagaceae and that the closest identified relative is Niabella soli (69.69% ANI). These data demonstrate that strain C216T represents a novel genus and novel species within the family Chitinophagaceae, for which we propose the name Mycovorax composti. The type strain is C216T (=DSM 114558T=LMG 32998T).

Bulk and Mapping Speciation Analyses Unveil the Pattern and Heterogeneity of Cu Species during Organic Waste Treatment

Organic wastes (OWs) can be a common source of copper (Cu) contamination of agricultural soils. Here we conducted a comprehensive study of 22 raw and treated OWs sampled at 6 different full-scale OW treatment plants. Bulk XANES analysis findings indicated that the Cu oxidation state was subject to changes throughout the OW treatment process, mostly depending on the anaerobic/aerobic conditions prevailing in each treatment stage. These changes were independent of the OW origin (agricultural, urban or industrial). Cu(I) prevailed in raw OWs and digestates (88-100%), whereas Cu(II) dominated in composts (46-100%). Bulk EXAFS analysis confirmed these observations and revealed that Cu(I) species in raw OWs and digestates consisted mainly of Cu(I)-sulfide (76-100%), while Cu(II) species (60-100%) in composts were Cu(II)-citrate, Cu(II)-carbonate and amorphous Cu(II)-phosphate. Interestingly, we observed that anaerobic digestion was conducive to the formation of crystallized Cu(I)-sulfides at the expense of nanosized and poorly crystalline Cu(I)-sulfide species, and that the recalcitrant Cu(I) species in composts was always crystallized Cu(I)-sulfide. XANES imaging analysis revealed Cu(II) species present in low proportions (2-4%) that were not detected using bulk XAS analysis in raw OWs and digestates. This demonstrated the potential of XANES imaging for probing minor species in complex matrices.

Development of a Rhizobium Seed Coating to Establish Lupine Species on Degraded Rangelands

Restoring native plant species on degraded landscapes is challenging. Symbiotic partners in the plant rhizosphere can aid in nutrient acquisition, pathogen protection, stress tolerance, and many other processes. However, these microbes are often absent in altered landscapes and need to be re-integrated to improve restoration efforts. We evaluated, within a laboratory setting, the ability of commercial and indigenous rhizobia strains to form nodules on lupine species used for rangeland seedings in the Great Basin region of the Western United States and ascertained if these strains could be applied through a seed coating. We also evaluated if a compost amendment applied via seed coating could further enhance the performance of the rhizobia strains. Our analysis showed that successful nodulation could occur using commercial and wildland-collected indigenous strains through either a liquid culture applied to seedlings or as a dry seed coating. However, the number of root nodules and the presence of a pink color (indicating nitrogen fixation) were typically higher in the commercial product than in the indigenous strains. Compost did not improve nodulation or the performance of the nodules; however, this treatment alone improved shoot growth. Overall, these results suggest that commercial rhizobium may be more effective in improving plant growth, and future research with native rhizobia may want to consider identifying strains compatible with seed-coating delivery. Longer-term studies are now merited for assessing how the rhizobia strains evaluated in this study influence plant growth, particularly in a field setting.

Safe Circular Food Systems: A Transdisciplinary Approach to Identify Emergent Risks in Food Waste Nutrient Cycling

With growing awareness of the environmental, economic, and social costs associated with food waste, there is a concerted effort on multiple scales to recover the nutrient value of discarded food. These developments are positive, but the rapid movement toward alternatives and the complexity of solving problems located at the intersection of economic, social, and environmental systems also have the potential to produce unanticipated risks. This paper draws upon long-term stakeholder-engaged research throughout New England, with a focus on Maine, to develop a transdisciplinary, systems-based model of the potential social, economic, and environmental risks of food waste nutrient cycling. Our effort is intended to help inform the creation of safe, functional, and environmentally benign circular food systems.

Mineral and Organic Fertilizers' Effect on the Growth of Young Argane Trees (Argania spinosa L.) and Soil Properties under Vulnerable Conditions

Argania spinosa (L.) Skeels is an endemic species to Morocco that has multiple uses. It plays multiple important roles in terms of its botanical, ecological, and economic properties. However, the domestication of this species will open up considerable economic opportunities for Morocco. Here, for the first time, we assessed the effect of different doses of compost and NPK fertilizers on the vegetative growth parameters, biochemical and antioxidant potential of the Argania spinosa plant, and soil properties. Over a two-year period (2022-2023), eight different treatments were applied across two experimental sites. These treatments included the following: T0 (Control), T1 (F1-80.50.70 g NPK/plant), T2 (F1-125.75.100 g NPK/plant), T3 (F2-160.100.140 g NPK/plant), T4 (F2-250.150.200 g NPK/plant), T5 (F1-2.5 kg/plant compost), T6 (F1-5 kg/plant compost), T7 (F2-5 kg/plant compost), and T8 (F2-10 kg/plant compost), with F1 and F2 being the frequencies of application. We compared several doses of fertilizers with no fertilization as a control. The results showed a significant influence of the compost and NPK fertilizer on the vegetative growth parameters. For the Tamjlojt site, the first year is important because treatments T3 and T4 significantly increased height by 71.94 ± 21.15% and 74.31 ± 12.31%, respectively. For the circumference, the results showed a significant improvement by the treatments T4 and T3, and T1 demonstrated the highest gain. For the collar diameter, all treatments showed a significant difference. The most notable difference was observed with treatments T3 and T7 with 115.63 ± 33.88% and 101.09 ± 20.84%, respectively. For the Rasmouka site, the second year was the most important. The treatments with the most important height increase were T7 and T8, with a value of 43.14 ± 10.06% and 36.44 ± 9.95%; the same was observed for collar diameter as a significant increase was found in T8 and T7 with a value of 55.05 ± 15.7% and 54.08 ± 9.64%. For the circumference parameter, the treatments that increased significantly this parameter were T8 and T7 with a value of 53.36 ± 15.11% and 50.34 ± 11.29% in 2023. In addition, the highest content of carbohydrates was recorded for the treatment T3 with a value of 148.89 ± 8.11 (mg EG/g). For phenolic determination, the highest value was 2532 ± 457.13 (µg GAE/mL), shown for treatment T1. For flavonoids, the treatments that showed a significant effect were T1 and T6 with a value of 2261.98 ± 184.61 and 1237.70 ± 95.65 (µg QE/mL), respectively. For the impact on soil properties, the electrical conductivity, at the Tamjlojt site, treatment T1 showed a significant increase to 1139.00 ± 241.30 (ms/cm), while at the Rasmouka site, treatment T8 showed a significant increase to 303.33 ± 9.33 (ms/cm). Concerning organic carbon, all treatments resulted in increased percentages of this parameter in the soil. For the Tamjlojt site, the T7 treatment had a significant positive effect on this parameter with a value of 0.87 ± 0.12%. For the Rasmouka site, the T3 treatment increased the percentage of organic carbon with a value of 1.17 ± 0.07%. In addition, the organic matter content showed an improvement with a value of 2.02 ± 0.12%. As there are no previous studies in Argania spinosa fertilization, this study greatly contributes to our understanding of the benefits of using different fertilizers at different doses, in particular T8 and T7 as organic fertilizers and T3, T4 as chemical ones, on argan growth, the biochemical and antioxidant properties of leaves, and its soil properties.

Detection of pan-azole resistant Aspergillus fumigatus in horticulture and a composting facility in Belgium

Azole resistance in Aspergillus fumigatus (ARAf) is becoming a worldwide health threat due to increasing occurrence in the environment. However, environmental surveillance programs are not commonly in place and are lacking in Belgium. Since no data on the occurrence of ARAf and the presence of hotspots for the selection of azole resistance is available in Belgium, a first study on the prevalence of ARAf in the environment was conducted. A total of 232 air and compost or soil samples were taken from two composting facilities, and from horticultural and agricultural crops. The azole susceptibility pattern was determined using the EUCAST method (E. Def. 9.4), and the cyp51A gene and its promotor region were sequenced in A. fumigatus isolates with phenotypic azole resistance. Six pan-azole-resistant A. fumigatus isolates were identified, originating from compost and horticultural crops. Four isolates carried the TR34/L98H mutation, and one isolate carried the TR46/Y121F/T289A mutation. However, we did not observe any ARAf isolates from agricultural crops. In conclusion, this study reported the first TR34/L98H and TR46/Y121F/T289A mutation isolated from a composting facility and horticulture in Belgium. The implementation of standardization in environmental surveillance of A. fumigatus on a European level would be beneficial in order to identify hotspots.

Application of Sensory Methods to Evaluate the Effectiveness of Solutions to Reduce the Exposure to Odour Nuisance and Ammonia Emissions from the Compost Heaps

Exposure to high concentrations of odours can result in health effects associated with direct health risks and irritation from nuisance. This investigation aimed to correlate aspects of the waste composting process with the emission levels of malodourous compounds. An essential optimisation criterion is the reduction of negative environmental impacts, particularly odour emissions. This study characterises odour concentration variations across various technological variants over different weeks of the composting process. A secondary objective is evaluating the efficacy of these variants, which differ in inoculation substances and compost heap composition. Olfactometric analyses were conducted using portable field olfactometers, enabling precise dilutions by mixing contaminated and purified air. The primary aim was to examine the correlation between selected odour parameters, determined via sensory analysis, and ammonia concentration during different composting weeks. Ammonia levels were measured using an RAE electrochemical sensor. Research shows that odour concentration is a significant indicator of compost maturity. In situ, olfactometric testing can effectively monitor the aerobic stabilisation process alone or with other methods. The most effective technological solution was identified by combining olfactometric and ammonia measurements and monitoring composting parameters, ensuring minimal odour emissions and the safety of employees and nearby residents.

Azole resistance mechanisms and population structure of the human pathogen Aspergillus fumigatus on retail plant products

Aspergillus fumigatus is a ubiquitous saprotroph and human-pathogenic fungus that is life-threatening to the immunocompromised. Triazole-resistant A. fumigatus was found in patients without prior treatment with azoles, leading researchers to conclude that resistance had developed in agricultural environments where azoles are used against plant pathogens. Previous studies have documented azole-resistant A. fumigatus across agricultural environments, but few have looked at retail plant products. Our objectives were to determine if azole-resistant A. fumigatus is prevalent in retail plant products produced in the United States (U.S.), as well as to identify the resistance mechanism(s) and population genetic structure of these isolates. Five hundred twenty-five isolates were collected from retail plant products and screened for azole resistance. Twenty-four isolates collected from compost, soil, flower bulbs, and raw peanuts were pan-azole resistant. These isolates had the TR34/L98H, TR46/Y121F/T289A, G448S, and H147Y cyp51A alleles, all known to underly pan-azole resistance, as well as WT alleles, suggesting that non-cyp51A mechanisms contribute to pan-azole resistance in these isolates. Minimum spanning networks showed two lineages containing isolates with TR alleles or the F46Y/M172V/E427K allele, and discriminant analysis of principle components identified three primary clusters. This is consistent with previous studies detecting three clades of A. fumigatus and identifying pan-azole-resistant isolates with TR alleles in a single clade. We found pan-azole resistance in U.S. retail plant products, particularly compost and flower bulbs, which indicates a risk of exposure to these products for susceptible populations and that highly resistant isolates are likely distributed worldwide on these products.IMPORTANCEAspergillus fumigatus has recently been designated as a critical fungal pathogen by the World Health Organization. It is most deadly to people with compromised immune systems, and with the emergence of antifungal resistance to multiple azole drugs, this disease carries a nearly 100% fatality rate without treatment or if isolates are resistant to the drugs used to treat the disease. It is important to determine the relatedness and origins of resistant A. fumigatus isolates in the environment, including plant-based retail products, so that factors promoting the development and propagation of resistant isolates can be identified.

Influence of Compost Amendments on Soil and Human Gastrointestinal Bacterial Communities during a Single Gardening Season

To measure associations between gardening with different compost amendments and the human gut microbiota composition, gardeners (n = 25) were provided with one of three types of compost: chicken manure (CM), dairy manure and plant material (DMP), or plant-based (P). Stool samples were collected before gardening (T1), after compost amendment (T2), and at peak garden harvest (T3). Compost and soil samples were collected. DNA was extracted, 16S rRNA libraries were established, and libraries were sequenced by Illumina MiSeq. Sequences were processed using mothur, and data were analyzed in R software version 4.2.2. Fast expectation-maximization microbial source tracking analysis was used to determine stool bacteria sources. At T2/T3, the gut microbiotas of P participants had the lowest Shannon alpha diversity, which was also the trend at T1. In stool from T2, Ruminococcus 1 were less abundant in the microbiotas of those using P compost as compared to those using CM or DMP. At T2, Prevotella 9 had the highest abundance in the microbiotas of those using CM compost. In participants who used CM compost to amend their gardening plots, a larger proportion of the human stool bacteria were sourced from CM compared to soil. Soil exposure through gardening was associated with a small but detectable change in the gardeners' gut microbiota composition. These results suggest that human interactions with soil through gardening could potentially impact health through alterations to the gut microbiota.

Evaluation of alternative methods of tunnel composting (submitted by the European Composting Network) II

Two alternative methods for producing compost in a tunnel, from certain category (Cat.) 3 animal by-products (ABP) and other non-ABP material, were assessed. The first method proposed a minimum temperature of 55°C for 72 h and the second 60°C for 48 h, both with a maximum particle size of 200 mm. The assessment of the Panel on Biological Hazards (BIOHAZ) exclusively focused on Cat. 3 ABP materials (catering waste and processed foodstuffs of animal origin no longer intended for human consumption). The proposed composting processes were evaluated for their efficacy to achieve a reduction of at least 5 log10 of Enterococcus faecalis and Salmonella Senftenberg (775W, H2S negative) and at least 3 log10 of relevant thermoresistant viruses. The applicant provided a list of biological hazards that may enter the composting process and selected parvoviruses as the indicator of the thermoresistant viruses. The evidence provided by the applicant included: (a) literature data on thermal inactivation of biological hazards; (b) results from validation studies on the reduction of E. faecalis, Salmonella Senftenberg 775W H2S negative and canine parvovirus carried out in composting plants across Europe; (c) and experimental data from direct measurements of reduction of infectivity of murine parvovirus in compost material applying the time/temperature conditions of the two alternative methods. The evidence provided showed the capacity of the proposed alternative methods to reduce E. faecalis and Salmonella Senftenberg 775W H2S negative by at least 5 log10, and parvoviruses by at least 3 log10. The BIOHAZ Panel concluded that the two alternative methods under assessment can be considered to be equivalent to the processing method currently approved in the Commission Regulation (EU) No 142/2011.

Optimizing Agroecological Measures for Climate-Resilient Olive Farming in the Mediterranean

In order to evaluate the potential of climate change mitigation measures on soil physiochemical properties, an experiment based on the application of five agroecological practices such as the addition of composted olive-mill wastes, recycling pruning residue, cover crops, organic insect manure, and reduced soil tillage, solely or combined, was conducted over two years (2020 to 2022) in a 48-year-old olive plantation. The results showed significant increases in soil water content during the spring and summer periods for the combined treatment (compost + pruning residue + cover crops) (ALL) compared to the control (CONT) by 41.6% and 51.3%, respectively. Also, ALL expressed the highest soil organic matter (4.33%) compared to CONT (1.65%) at 0-10 cm soil depth. When comparing soil nutrient contents, ALL (37.86 mg kg-1) and cover crops (COVER) (37.21 mg kg-1) had significant increases in soil nitrate compared to CONT (22.90 mg kg-1), the lowest one. Concerning exchangeable potassium, ALL (169.7 mg kg-1) and compost (COMP) (168.7 mg kg-1) were higher than CONT (117.93 mg kg-1) at the 0-10 cm soil depth and had, respectively an increase of 100.9% and 60.7% in calcium content compared to CONT. Over the experimental period, the implementation of the five agroecological management practices resulted in enhanced soil fertility. In a long-term Mediterranean context, this study suggests that these sustainable practices would significantly benefit farmers by improving agroecosystem services, reducing reliance on synthetic fertilizers, optimizing irrigation water use, and ultimately contributing towards a circular economy.

Valorization of kiwi waste through composting

Kiwi waste from the calibration process is a major environmental problem of kiwi production due to landfill deposition. This work aims to contribute to the agronomic use of recycled kiwi waste through composting. With this objective, a composting experiment was carried out with kiwi fruit waste mixed with 5%, 10% and 20% (fresh weight) of wheat straw from bundles used to protect kiwifruit trunks from frost, as abulking agent to increase aeration, in the piles 5S, 10S and 20S, respectively. The highest temperatures for piles 5S and 10S were above 60°C, whereas the temperature did not reach 40°C in the pile with the highest straw content (20S) because the aeration increased heat loss in addition to increased C/N ratio of this pile. Also, the amount of organic matter mineralized decreased with increasing amount of straw because of the high C/N ratio of the straw. The highest total N (29.7 g kg-1) and the lowest C/N ratio (13) of the compost with 5% of straw is important from the agricultural point of view to promote N availability. In contrast, the high electrical conductivity (4.6 dS m-1) of this compost increases the risk of salt accumulation in the soil. Our results show that the compost with 10% straw, with high degree of maturation, absence of poor hygiene indicators as coliforms and pathogens as Salmonella sp., high organic matter content and rich in nutrients, together with the adequate compost pH and low electrical conductivity improves compost quality.

Compost Filling Methods Affect Green Mold Disease Incidence in Commercial Mushrooms

Green mold (Trichoderma aggressivum) is an invasive disease of commercial mushrooms introduced into the United States from Europe that now has spread to commercial mushrooms throughout North America. We examined potential sources of invasive green mold inoculum and the association with different compost filling technologies on a large actively producing commercial mushroom farm. Green mold foci were sampled bed by bed, which generated 20,906 data points. Logistic regression was used to determine treatment differences. Mechanical filling of compost into the beds reduced green mold incidence over hand filling, apparently due to the reduced incidence of worker contact with the floor and between beds. Lower growing beds located closer to the floor had a higher incidence of green mold for both mechanical and hand-filled beds. We conclude that mechanical filling and generally reducing contact with the floor and between beds will reduce spread of green mold in commercial mushroom production.

Municipal Compost Public Health, Waste Management, and Urban Agriculture: A Decadal Study of Fugitive Pb in City of Boston, Massachusetts, USA

Compostable materials constitute roughly half of waste generated globally, but only 5% of waste is actually processed through composting, suggesting that expanding compost programs may be an effective way to process waste. Compostable waste, if properly collected and processed, has value-added end use options including: residential and park landscaping, remediation of brownfield sites, and as growing media in urban agriculture (UA). Since 2001, our lab has partnered with The Food Project, a non-profit focused on youth leadership development through urban farming. From 2006 to 2022 we collected compost materials that were delivered to the farm from a variety of local sources and analyzed a suite of biogeochemical properties including lead (Pb) concentrations, organic carbon, and grain size distribution. Pb concentrations of Boston's municipal compost always exceeded the current City of San Francisco soil and compost purchase standard (80 μg/g). In 2012 Boston's composting program was halted when it exceeded the 400 μg/g Environmental Protection Agency's Pb in soil benchmark. Urban Pb is geomobile and must be managed to minimize resuspension and transport of fines whose Pb concentration is often elevated compared to bulk compost. Consequently, urban farmers have to source lower Pb compost from suburban suppliers at significantly greater cost. Over a 15 year period and through several city vendor contracts, Pb concentrations in municipal compost remain at levels that warrant continued surveillance and risk assessment.

Enhanced Biodegradation Rate of Poly(butylene adipate-co-terephthalate) Composites Using Reed Fiber

To enhance the degradability of poly(butylene adipate-co-terephthalate) (PBAT), reed fiber (RF) was blended with PBAT to create composite materials. In this study, a fifteen day degradation experiment was conducted using four different enzyme solutions containing lipase, cellulase, Proteinase K, and esterase, respectively. The degradation process of the sample films was analyzed using an analytical balance, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The PBAT/RF composites exhibited an increased surface hydrophilicity, which enhanced their degradation capacity. Among all the enzymes tested, lipase had the most significant impact on the degradation rate. The weight loss of PBAT and PBAT/RF, caused by lipase, was approximately 5.63% and 8.17%, respectively. DSC analysis revealed an increase in the melting temperature and crystallinity over time, especially in the film containing reed fibers. FTIR results indicated a significant weakening of the ester bond peak in the samples. Moreover, this article describes a biodegradation study conducted for three months under controlled composting conditions of PBAT and PBAT/RF samples. The results showed that PBAT/RF degraded more easily in compost as compared to PBAT. The lag phase of PBAT/RF was observed to decrease by 23.8%, while the biodegradation rate exhibited an increase of 11.8% over a period of 91 days. SEM analysis demonstrated the formation of more cracks and pores on the surface of PBAT/RF composites during the degradation process. This leads to an increased contact area between the composites and microorganisms, thereby accelerating the degradation of PBAT/RF. This research is significant for preparing highly degradable PBAT composites and improving the application prospects of biodegradable green materials. PBAT/RF composites are devoted to replacing petroleum-based polymer materials with sustainable, natural materials in advanced applications such as constructional design, biomedical application, and eco-environmental packaging.

The influence of a soil amendment on the abundance and interaction of arbuscular mycorrhizal fungi with arable soils and host winter wheat

Arbuscular mycorrhizal (AM) fungi have been shown to be associated with an estimated 70 % of vascular terrestrial plants. Such relationships have been shown to be sensitive to soil disturbance, for example, tillage in the preparation of a seed bed. From the application of arable soil management, AM fungal populations have been shown to be negatively impacted in abundance and diversity, reducing plant growth and development. The present study aims to utilise two sources (multipurpose compost and a commercial inocula) of mycorrhizal fungi for the amendment of arable soils supporting Zulu winter wheat under controlled conditions and quantify plant growth responses. A total of nine fields across three participating farms were sampled, each farm practicing either conventional, reduced, or zero tillage soil management exclusively. Soil textures were assessed for each sampled soil. Via the employment of AM fungal symbiosis quantification methods, AM fungi were compared between soil amendments and their effects on crop growth and development. The present study was able to quantify a mean 6 cm increase to crop height (P<0.001), 10 cm reduction to root length corresponding with a 2.45-fold increase in AM fungal arbuscular structures (P<0.001), a 1.15-fold increase in soil glomalin concentration corresponding to a 1.26-fold increase in soil carbon, and a 1.32-fold increase in the relative abundance of molecular identified AM fungal sequences for compost amended soils compared to control samples. Mycorrhizal inocula, however, saw no change to crop height or root length, AM fungal arbuscules were reduced by 1.43-fold, soil glomalin was additionally reduced by 1.55-fold corresponding to a reduction in soil carbon by 1.31-fold, and a reduction to relative AM fungal species abundance by 1.26-fold. The present study can conclude the addition of compost as an arable soil amendment is more beneficial for the restoration of AM fungi beneficial to wheat production and soil carbon compared to the addition of a commercial mycorrhizal inocula.

Differential Gene Expression Patterns in Peach Roots under Non-Uniform Soil Conditions in Response to Organic Matter

Organic matter (OM) amendments are often encouraged in sustainable agriculture programs but can create heterogeneous soil environments when applied to perennial crops such as peaches (Prunus persica (L.) Batsch). To better understand the responses of peach roots to non-uniform soil conditions, transcriptomic analysis was performed in a split-root study using uniform soil (the same soil type for all roots) or non-uniform soil (different soil types for each half of the root system) from either (1) autoclaved sand (S), (2) autoclaved sand with autoclaved compost (A), or (3) autoclaved sand with compost which included inherent biological soil life (B). Each uniform soil type (S, A, and B) was grouped and compared by uniform and non-uniform soil comparisons for a total of nine treatments. Comparisons revealed peach roots had differentially expressed genes (DEGs) and gene ontology terms between soil groups, with the S and B groups having a range of 106-411 DEGs and the A group having a range of 19-94 DEGs. Additionally, six modules were identified and correlated (p > 0.69) for six of the nine treatment combinations. This study broadly highlights the complexity of how OM and biological life in the rhizosphere interact with immediate and distant roots and sheds light on how non-homogenous soil conditions can influence peach root gene expression.

Manipulating Agaricus bisporus developmental patterns by passaging microbial communities in complex substrates

IMPORTANCE

Agaricus bisporus is an economically important edible mushroom and manipulating its developmental patterns is crucial for maximizing yield and quality. One of the potential strategies for achieving such a goal is passaging microbial communities in compost or casing. The current study demonstrated that passaging substrates develop enriched microbial communities, and after a few passages, certain levels of changes in mushroom developmental patterns (the timing of fruiting bodies formation) were observed as well as shifts in the bacterial communities. Overall, a better understanding of the complex interactions between microorganisms present in the cultivation system may help farmers and researchers to develop more efficient and sustainable cultivation practices that can both benefit the environment and human health.

A Thermophile-Fermented Compost Modulates Intestinal Cations and the Expression of a Juvenile Hormone-Binding Protein Gene in the Female Larvae of Hercules Beetle Dynastes hercules (Coleoptera: Scarabaeidae)

The Hercules beetle larvae grow by feeding on humus, and adding a thermophile-fermented compost to the humus can upregulate the growth of female larvae. In this study, the effects of compost on the intestinal environment, including pH, cation concentrations, and organic acid concentrations of intestinal fluids, were investigated, and the RNA profile of the fat body was determined. Although the total intestinal potassium ions were similar between the larvae grown without compost (control larvae) and those with compost (compost larvae), the proportion of potassium ions in the midgut of the compost larvae drastically increased. In the midgut, an unidentified organic acid was the most abundant, and its concentration increased in the compost larvae. Transcriptome analysis showed that a gene encoding hemolymph juvenile-binding protein (JHBP) was expressed in the compost female larvae and not in the control female larvae. Expression of many genes involved in the defensive system was decreased in the compost female larvae. These results suggest that the female-specific enhancement of larval growth by compost was associated with the increased JHBP expression under conditions in which the availability of nutrition from the humus was improved by an increase in potassium ions in the midgut.

Mild Chemical Treatment of Unsorted Urban Food Wastes

Municipal biowastes are conventionally treated by assessed anaerobic and aerobic fermentation to produce biogas, anaerobic digestate, and compost. Low-temperature hydrolysis and the oxidation of the digestate and compost, which are still at the experimental stage, are known to yield water-soluble value-added chemical specialities for use in different sectors of the chemical industry and in agriculture. The present paper reports the application of the two chemical reactions to the biowastes before fermentation. The products obtained in this manner are compared with those obtained from the chemical reactions applied to the fermented biowastes. Based on the experimental results, the paper discusses the expected environmental and economic benefits of the above chemical processes and products in comparison with the products obtained by other known biotechnologies for the valorisation of biomass as a feedstock for the biobased chemical industry. The results point out that a sustainable biowaste-based refinery that produces biofuel and biobased chemicals may be developed by integrating chemical and fermentation technologies.