Screening Ultra-Stable (Phenazine)dioxyalkanocic Acids with Varied Water-Solubilizing Chain Lengths for High-Capacity Aqueous Redox Flow Batteries.

Aqueous redox flow batteries (ARFBs) hold great potential for large-scale energy storage. Recently, research on aqueous flow batteries has shifted toward water-soluble organic molecules with redox capabilities to reduce the use of mineral resources. The chemical and electrochemical stabilities of organic compounds are heavily influenced by their functional groups and reaction sites. In this study, we present a low-cost synthesis of the O-alkyl-carboxylate-functionalized derivatives of 2,3-dihydroxyphenazine, namely, phenazine-(2,3-diyl) dioxy dibutyric acid (DBEP) and phenazine-(2,3-diyl)dioxy diacetic acid (DAEP), which serve as negolytes and exhibit good reversibility and high redox kinetics. The evidence is provided to clarify the capacity degradation mechanisms of DAEP and DBEP by a series of comprehensive characterizations. Similar to anthraquinones functionalized with alkyl chains, the main degradation mechanism of DAEP modified with acetic acid is due to side chain loss. Longer side chains are more stable and can withstand long-term electrochemical reactions. DBEP modified with butyric acid exhibits superior chemical and electrochemical stability. Our results demonstrate that rational molecular design and suitable membranes, such as the alkaline ARFBs based on DBEP negolyte, potassium ferrocyanide (K4Fe(CN)6) posolyte, and custom sulfonated poly(ether ether ketone) membrane, can deliver a high open-circuit voltage of 1.17 V and high capacity retention of 99.997% per cycle for over 1000 cycles at 50 mA cm-2. This study highlights the importance of not only considering the modification position of the molecules but also focusing on the influence of various side chains on the redox core's stability toward sustainable grid-scale energy storage applications.

Synergistic effects of chemical additives and mature compost on reducing H2S emission during kitchen waste composting.

Additives could improve composting performance and reduce gaseous emission, but few studies have explored the synergistic of additives on H2S emission and compost maturity. This research aims to make an investigation about the effects of chemical additives and mature compost on H2S emission and compost maturity of kitchen waste composting. The results showed that additives increased the germination index value and H2S emission reduction over 15 days and the treatment with both chemical additives and mature compost achieved highest germination index value and H2S emission reduction (85%). Except for the treatment with only chemical additives, the total sulfur content increased during the kitchen waste composting. The proportion of effective sulfur was higher with the addition of chemical additives, compared with other groups. The relative abundance of H2S-formation bacterial (Desulfovibrio) was reduced and the relative abundance of bacterial (Pseudomonas and Paracoccus), which could convert sulfur-containing substances and H2S to sulfate was improved with additives. In the composting process with both chemical additives and mature compost, the relative abundance of Desulfovibrio was lowest, while the relative abundance of Pseudomonas and Paracoccus was highest. Taken together, the chemical additives and mature compost achieved H2S emission reduction by regulating the dynamics of microbial community.

Enhanced organic degradation and microbial community cooperation by inoculating Bacillus licheniformis in low temperature composting.

Microbial activity and interaction are the important driving factors in the start-up phase of food waste composting at low temperature. The aim of this study was to explore the effect of inoculating Bacillus licheniformis on the degradation of organic components and the potential microbe-driven mechanism from the aspects of organic matter degradation, enzyme activity, microbial community interaction, and microbial metabolic function. The results showed that after inoculating B. licheniformis, temperature increased to 47.8°C on day 2, and the degradation of readily degraded carbohydrates (RDC) increased by 31.2%, and the bioheat production increased by 16.5%. There was an obvious enhancement of extracellular enzymes activities after inoculation, especially amylase activity, which increased by 7.68 times on day 4. The inoculated B. licheniformis colonized in composting as key genus in the start-up phase. Modular network analysis and Mantel test indicated that inoculation drove the cooperation between microbial network modules who were responsible for various organic components (RDC, lipid, protein, and lignocellulose) degradation in the start-up phase. Metabolic function prediction suggested that carbohydrate metabolisms including starch and sucrose metabolism, glycolysis / gluconeogenesis, pyruvate metabolism, etc., were improved by increasing the abundance of related functional genes after inoculation. In conclusion, inoculating B. licheniformis accelerated organic degradation by driving the cooperation between microbial network modules and enhancing microbial metabolism in the start-up phase of composting.

Risk assessment of three sheep stocking modes via identification of bacterial genomes carrying antibiotic resistance genes and virulence factor genes.

In order to protect the prairie ecological environment, intensive farming has become a prevalent method of sheep stocking. However, the link between captivity stocking mode and ecological risk of sheep feces is still poorly understood. In this study, metagenomics was used to identify the environmental risk of sheep feces among three stocking modes. Our results showed that captivity mode (C) elevated antibiotic resistance in feces, with the abundance of antibiotic resistance genes (ARGs) (5.381 copies/cell) higher than that of half-pen stocking (Fh) (1.093 copies/cell) and grazing mode (Fr) (0.315 copies/cell) (Duncan's test, P < 0.05). Virulence factor genes (VFGs) analysis showed offensive virulence factors had the highest abundance in captivity feces (C: 3.826 copies/cell, Fh: 0.342 copies/cell, Fr: 0.163 copies/cell) (Duncan's test, P < 0.05). 15 metagenome-assembled genomes (MAGs) were identified as potential pathogenic antibiotic resistant bacteria (PARB) and revealed that Escherichia, Klebsiella may be the main host of ARGs and VFGs in sheep feces. Furthermore, the minimal inhibition concentrations (MIC) of tetracycline of E. coli in the captivity feces was 8.6 times and 4.7 times than that of grazing and half-pen stocking samples, respectively. The Non-metric multidimensional scaling (NMDS) revealed that high stocking density leads to feces causing increased harm to the environment. Although feces from sheep raised in captivity and half-pen stocking modes are easier to collect, they are more harmful to the environment and aerobic composting should be done before their application to farmland. This work provides a guideline for better control of the environmental risk of sheep feces from different stocking modes.

Total and denitrifying bacterial communities associated with the interception of nitrate leaching by carbon amendment in the subsoil.

Nitrate leaching is severe in greenhouse where excessive nitrogen is often applied to maintain high crop productivities. In this study, we investigated the effects of carbon amendment in the subsoil on nitrate leaching and the emission of greenhouse gases (CH4 and N2O) using a soil column experiment. Carbon amendment resulted in over 39% reduction in nitrate leaching and 25.3% to 60.6% increase of total N content in the subsoil zone as compared to non-amended control. Strikingly, the abundance of nirS, nosZ, and 16S rRNA were higher in the treatment than the corresponding controls while no significant effect was detected for nirK. Carbon amendment explained 14%, 10%, and 4% of the variation in the community of nosZ, nirS, and nirK, respectively. It also considerably (more than 7 times) enriched genera such as Anaerovorax, Pseudobacteroides, Magnetospirillum, Prolixibacter, Sporobacter, Ignavibacterium, Syntrophobacter, Oxobacter, Hydrogenispora, Desulfosporomusa, Mangrovibacterium, and Sporomusa, as revealed by the analysis of 16S rRNA amplicon. Network analysis further uncovered that carbon amendment enriched three microbial hubs which mainly consists of positively correlated nirS, nosZ, and anaerobic bacterial populations. In summary, carbon amendment in the subsoil mitigated nitrate leaching and increased the nitrogen pool by possible activation of denitrifying and anaerobic bacterial populations. KEY POINTS: • Carbon amendment in subsoil reduced NO3- leaching by over 39% under high N input. • Carbon amendment increased the total N in subsoil from 25.3% to 60.6%. • Carbon amendment enriched nirS- and nosZ-type denitrifying bacteria in subsoil.

One-step immunoassay for the insecticide carbaryl using a chicken single-chain variable fragment (scFv) fused to alkaline phosphatase.

Immunoassays provide a high-throughput method for monitoring pesticides in foods and the environment. Due to easy generation and capable of being manipulated, chicken single-chain variable fragment (scFv) is attractive in the development of immunoassays for pesticides. Two scFvs (X1 and X2) against the insecticide carbaryl were generated from a chicken immunized with hapten C1 conjugated to keyhole limpet hemocyanin and fused with alkaline phosphatase (AP) to develop a rapid one-step enzyme-linked immunosorbent assay for this pesticide. X2-AP showed higher binding affinity to carbaryl than X1-AP. The X2-AP-based ELISA had a half-maximum signal inhibition concentration of 15 ng mL-1 and a limit of detection of 1.6 ng mL-1. This assay showed negligible cross-reactivity with other carbamate pesticides (<0.1%) and low cross-reactivity with 1-naphthol (5%). The average recoveries of carbaryl spiked in soil, apple and pear samples by the one-step assay ranged from 90% to 114% and agreed well with those of high-performance liquid chromatography. The chicken scFv-based assay showed promise as a high-throughput screening tool for carbaryl in environmental and food matrices.

Development of a one-step immunoassay for triazophos using camel single-domain antibody-alkaline phosphatase fusion protein.

Triazophos is mainly used in Asian and African countries for the control of insects in agricultural production. Camelid variable domains of heavy-chain antibodies (VHHs) show great promise in monitoring environmental chemicals such as pesticides. To improve the rate of success in the generation of VHHs against triazophos, genes specifically encoding VHH fragments from the unique allotype IgG3a of an immunized Camelus bactrianus were amplified by using a pair of novel primers and introduced to construct a diverse VHH library. Five out of seven isolated positive clones, including the VHH T1 with the highest affinity to triazophos, were derived from the allotype IgG3a. A one-step enzyme-linked immunosorbent assay (ELISA) using VHH T1 genetically fused with alkaline phosphatase (AP) had a half-maximum inhibition concentration of 6.6 ng/mL for triazophos. This assay showed negligible cross-reactivity with a list of important organophosphate pesticides (< 0.1%). The average recoveries of triazophos from water, soil, and apple samples determined by the one-step ELISA ranged from 83 to 108%, having a good correlation with those by a gas chromatography mass spectrometry (R2 = 0.99). The VHH-AP fusion protein shows potential for the analysis of triazophos in various matrices.

Development of an immunoassay for the detection of carbaryl in cereals based on a camelid variable heavy-chain antibody domain.

BACKGROUND: The variable domain of camelid heavy-chain antibodies (VHH) is increasingly being adapted to detect small molecules in various matrices. The insecticide carbaryl is widely used in agriculture while its residues have posed a threat to food safety and human health. RESULTS: VHHs specific for carbaryl were generated from an alpaca immunized with the hapten CBR1 coupled to keyhole limpet hemocyanin. An enzyme-linked immunosorbent assay (ELISA) based on the VHH C1 and the coating antigen CBR2-BSA was developed for the detection of carbaryl in cereals. This assay, using an optimized assay buffer (pH 6.5) containing 10% methanol and 0.8% NaCl, has a half-maximum signal inhibition concentration of 5.4 ng mL-1 and a limit of detection (LOD) of 0.3 ng mL-1 for carbaryl, and shows low cross reactivity (≤0.8%) with other tested carbamates. The LOD of carbaryl using the VHH-based ELISA was 36 ng g-1 in rice and maize and 72 ng g-1 in wheat. Recoveries of carbaryl in spiked rice, maize and wheat samples were in the range of 81-106%, 96-106% and 83-113%, respectively. Relative standard deviations of repeatability and intra-laboratory reproducibility were in the range of 0.8-9.2% and 2.9-9.7%, respectively. CONCLUSION: The VHH-based ELISA was highly effective in detecting carbaryl in cereal samples after simple sample extraction and dilution. © 2019 Society of Chemical Industry.

Shifts in abundance and diversity of mobile genetic elements after the introduction of diverse pesticides into an on-farm biopurification system over the course of a year.

Biopurification systems (BPS) are used on farms to control pollution by treating pesticide-contaminated water. It is assumed that mobile genetic elements (MGEs) carrying genes coding for enzymes involved in degradation might contribute to the degradation of pesticides. Therefore, the composition and shifts of MGEs, in particular, of IncP-1 plasmids carried by BPS bacterial communities exposed to various pesticides, were monitored over the course of an agricultural season. PCR amplification of total community DNA using primers targeting genes specific to different plasmid groups combined with Southern blot hybridization indicated a high abundance of plasmids belonging to IncP-1, IncP-7, IncP-9, IncQ, and IncW, while IncU and IncN plasmids were less abundant or not detected. Furthermore, the integrase genes of class 1 and 2 integrons (intI1, intI2) and genes encoding resistance to sulfonamides (sul1, sul2) and streptomycin (aadA) were detected and seasonality was revealed. Amplicon pyrosequencing of the IncP-1 trfA gene coding for the replication initiation protein revealed high IncP-1 plasmid diversity and an increase in the abundance of IncP-1ß and a decrease in the abundance of IncP-1ε over time. The data of the chemical analysis showed increasing concentrations of various pesticides over the course of the agricultural season. As an increase in the relative abundances of bacteria carrying IncP-1ß plasmids also occurred, this might point to a role of these plasmids in the degradation of many different pesticides.

Promoting agricultural waste-driven denitrification and nitrogen sequestration with nano-enabled strategy.

Nanotechnology and biotechnology offer promising avenues for bolstering food security through the facilitation of soil nitrogen (N) sequestration and the reduction of nitrate leaching. Nonetheless, a comprehensive and mechanistic evaluation of their effectiveness and safety remains unclear. In this study, a soil remediation strategy employing nano-Fe3O4 and straw in N-contaminated soil was developed to elucidate N retention mechanisms via diverse metagenomics techniques. The findings revealed that subsoil amended with straw, particularly in conjunction with nano-Fe3O4, significantly increased subsoil N content (53.2%) and decreased nitrate concentration (74.6%) in leachate. Furthermore, the enrichment of functional genes associated with N-cycling, sulfate, nitrate, and iron uptake, along with chemotaxis, and responses to environmental stimuli or microbial collaboration, effectively mitigates nitrate leaching while enhancing soil N sequestration. This study introduces a pioneering approach utilizing nanomaterials in soil remediation, thereby offering the potential for the cultivation of safe vegetables in high N input greenhouse agriculture.

Essential role of composting industry in achieving China's dual-carbon goals: Case studies from Chinese composting companies.

Composting is one of the primary methods for organic waste recycling in China. This study aims to analyze the product quality of organic fertilizer enterprises from the perspective of actual production and the relationship between production process variations and organic matter content in organic fertilizers based on 348 samples from 229 organic fertilizer companies across 22 provinces. Results showed that fertilizers produced through composting processes contain higher organic matter, averaging 45.42 %, compared to commercial organic fertilizers and bio-organic fertilizers. Raw materials, equipment, methods, operational scale, and personnel structure are key factors affecting the content of organic matter in products. Optimizing equipment and processes in Chinese organic fertilizer companies could increase organic matter content to 49.3 %, potentially reducing annual carbon emissions by an estimated 3.07 to 6.97 billion kg of CO2 equivalent, thereby supporting the realization of dual carbon goals.

Increased abundance and transferability of resistance genes after field application of manure from sulfadiazine-treated pigs.

Spreading manure containing antibiotics in agriculture is assumed to stimulate the dissemination of antibiotic resistance in soil bacterial populations. Plant roots influencing the soil environment and its microflora by exudation of growth substrates might considerably increase this effect. In this study, the effects of manure from pigs treated with sulfadiazine (SDZ), here called SDZ manure, on the abundance and transferability of sulfonamide resistance genes sul1 and sul2 in the rhizosphere of maize and grass were compared to the effects in bulk soil in a field experiment. In plots that repeatedly received SDZ manure, a significantly higher abundance of both sul genes was detected compared to that in plots where manure from untreated pigs was applied. Significantly lower abundances of sul genes relative to bacterial ribosomal genes were encountered in the rhizosphere than in bulk soil. However, in contrast to results for bulk soil, the sul gene abundance in the SDZ manure-treated rhizosphere constantly deviated from control treatments over a period of 6 weeks after manuring, suggesting ongoing antibiotic selection over this period. Transferability of sulfonamide resistance was analyzed by capturing resistance plasmids from soil communities into Escherichia coli. Increased rates of plasmid capture were observed in samples from SDZ manure-treated bulk soil and the rhizosphere of maize and grass. More than 97% of the captured plasmids belonged to the LowGC type (having low G+C content), giving further evidence for their important contribution to the environmental spread of antibiotic resistance. In conclusion, differences between bulk soil and rhizosphere need to be considered when assessing the risks associated with the spreading of antibiotic resistance.

Rhizocompetence and antagonistic activity towards genetically diverse Ralstonia solanacearum strains--an improved strategy for selecting biocontrol agents.

Bacterial wilt caused by Ralstonia solanacearum is a serious threat for agricultural production in China. Eight soil bacterial isolates with activity against R. solanacearum TM15 (biovar 3) were tested in this study for their in vitro activity towards ten genetically diverse R. solanacearum isolates from China. The results indicated that each antagonist showed remarkable differences in its ability to in vitro antagonize the ten different R. solanacearum strains. Strain XY21 (based on 16S rRNA gene sequencing affiliated to Serratia) was selected for further studies based on its in vitro antagonistic activity and its excellent rhizocompetence on tomato plants. Under greenhouse conditions XY21 mediated biocontrol of tomato wilt caused by seven different R. solanacearum strains ranged from 19 to 70 %. The establishment of XY21 and its effects on the bacterial community in the tomato rhizosphere were monitored by denaturing gradient gel electrophoresis of 16S rRNA gene fragments PCR-amplified from total community DNA. A positive correlation of the in vitro antagonistic activities of XY21 and the actual biocontrol efficacies towards seven genetically different R. solanacearum strains was found and further confirmed by the efficacy of XY21 in controlling bacterial wilt under field conditions.

Role of fungal communities and their interaction with bacterial communities on carbon and nitrogen component transformation in composting with different phosphate additives.

The aim of the study was to compare the succession of fungal community and their interaction with bacterial community during pig manure composting with different phosphate additives and further to identify microbial roles on the transformation of carbon and nitrogen (C&N) components and compost maturity. The results showed that the composition of fungal community was significantly affected by pH in composting and acidic phosphate might postpone the C&N degradation process. Network analysis showed that phosphate additives, especially acidic additives, could increase the interaction of microbial community but acidic phosphate decreased the core fungi:bacteria ratio. Redundancy analysis indicated that the interactions between bacterial and fungal communities played more roles than individual contribution of bacteria or fungi for C&N conversion of composting. Structural equation modeling suggested that bacterial community was positively directly correlated to C&N loss and the participation of fungal community significantly benefited the maturity of composting. pH exhibited a great intermediated role for driving C&N conversion, maturity, and safety of composts by regulating bacterial and fungal community in composting with phosphate addition, which suggested a fast-composting way based on pH regulation by additives.

Insight into the dynamic microbial community and core bacteria in composting from different sources by advanced bioinformatics methods.

Microbial communities are important for high composting efficiency and good quality composts. This study was conducted to compare the changes of physicochemical and bacterial characteristics in composting from different raw materials, including chicken manure (CM), duck manure (DM), sheep manure (SM), food waste (FW), and vegetable waste (VW). The role and interactions of core bacteria and their contribution to maturity in diverse composts were analyzed by advanced bioinformatics methods combined sequencing with co-occurrence network and structural equation modeling (SEM). Results indicated that there were obviously different bacterial composition and diversity in composting from diverse sources. FW had a low pH and different physiochemical characteristics compared to other composts but they all achieved similar maturity products. Redundancy analysis suggested total organic carbon, phosphorus, and temperature governed the composition of microbial species but key factors were different in diverse composts. Network analysis showed completely different interactions of core bacterial community from diverse composts but Thermobifida was the ubiquitous core bacteria in composting bacterial network. Sphaerobacter and Lactobacillus as core genus were presented in the starting mesophilic and thermophilic phases of composting from manure (CM, DM, SM) and municipal solid waste (FW, VW), respectively. SEM indicated core bacteria had the positive, direct, and the biggest (> 80%) effects on composting maturity. Therefore, this study presents theoretical basis to identify and enhance the core bacteria for improving full-scale composting efficiency facing more and more organic wastes.

Effects of chemical additives and mature compost on reducing nitrogen loss during food waste composting.

This study is aimed at adding different types of mature compost and sulfur powder, as additives into food waste composting to investigate the effect on nitrogen loss and compost maturity. The composting experiment used the in-vessel composting method and was conducted continuously for 15 days. High-throughput sequencing was used to analyze the bacterial community during composting. Results showed that the secondary fermentation mature compost mixed with sulfur powder group had the most reduction of ammonia emission (56%) and the primary fermentation mature compost amendments were the most effective for nitrous oxide emission reduction (37%). The temperature, pH, and nitrogen forms of transformation of the pile significantly affect the nitrogen loss during composting. Firmicutes helped to promote the rapid warming of the pile, and Actinobacteria and Proteobacteria played an important role in decomposition of organic matter. Thermobifida and Ureibacillus had a main contribution to the rapid degradation of organic matter in the process of composting. The relative abundance of nitrogen-fixing bacteria was higher, and the relative abundance of predominantly ammonifying and denitrifying bacteria was lower than the control group, with the addition of different additives.

Changes in bacterial diversity, co-occurrence pattern, and potential pathogens following digestate fertilization: Extending pathogen management to field for anaerobic digestion of livestock manure.

Digestate can spread pathogens into agroecosystem, posing serious threats to public health. However, the effect of digestate fertilization on digestate- or soil-borne pathogens has not been fully explored. Herein, two settings of microcosm experiment were performed with arable soil and digestate collected at two sites (Beilangzhong or Shunyi) to dissect the succession of the total and potential pathogenic bacterial communities following digestate fertilization. Each experimental setting consisted of three treatments, including digestate aerobically incubated in sterilized soil, and soil amended with sterilized or non-sterilized digestate. Digestate-borne potential pathogenic bacteria were enriched after the aerobic incubation, with Streptococcus sobrinus in the Beilangzhong setting, and Escherichia coli and Enterococcus faecium in the Shunyi setting. Potential soil-borne pathogenic bacteria, such as Acinetobacter lowffii and Pseudomonas fluorescens, were stimulated by the sterilized digestate in the Shunyi setting. Interestingly, S. sobrinus, E. coli, and Ent. faecium did not increase when digestate was amended into the non-sterilized soil, suggesting that soil microorganisms can inhibit the resurgence of these digestate-borne pathogens. A large-scale survey further revealed that organic fertilization exerted a site-dependent effect on different species of potential pathogen, but it did not enrich the total relative abundance of potential pathogenic bacteria in soils. Collectively, these results highlight that pathogen management of anaerobic digestion of livestock manure needs to be extended from anaerobic reactor to field.

Bacillus velezensis BER1 enriched Flavobacterium daejeonense-like bacterium in the rhizosphere of tomato against bacterial wilt.

Beneficial microorganisms can protect crop from phytopathogens, and modify rhizosphere microbiome. However, it is not well-understood whether or how do rhizosphere microorganisms which respond to bioagents contribute to disease suppression. Bacillus velezensis BER1 and tomato bacterial wilt caused by Ralstonia solanacearum were selected as models to disentangle the interactions and mechanisms in the rhizosphere. Bacillus velezensis BER1 greatly suppressed tomato bacterial wilt by over 49.0%, reduced R. solanacearum colonization in the rhizosphere by 36.3%, and significantly enriched two Flavobacterium ASVs (1357 and 2401). A novel colony loop-mediated isothermal amplification (LAMP) assay system was developed to screen out Flavobacterium from tomato rhizosphere bacterial isolates. In vitro tests revealed that cocultivating BER1 with Flavobacterium C45 increased biofilm formation by 18.6%. Climate chamber experiment further revealed that Flavobacterium C45 improved the control efficiency of BER1 on tomato bacterial wilt by 46.0%, decreased the colonization of R. solanacearum in the rhizosphere by 43.1% and elevated the transcription of plant defense gene PR1α in tomato by 45.4%. In summary, Flavobacterium C45 boosted the ability of B. velezensis BER1 to prevent bacterial wilt and the colonization of R. solanacearum, highlighting the importance of helper bacteria on elevating the efficiency of biological control.

Bacterial wilt suppressive composts: Significance of rhizosphere microbiome.

Composts are often suppressive to several plant diseases, including the devastating bacterial wilt caused by Ralstonia solanacearum. However, the underlying mechanisms are still unclear. Herein, we carried out an experiment with 38 composts collected from different factories in China to study the interlinking among bacterial wilt suppression, the physicochemical properties and bacterial community of the compost, and bacterial community in the rhizosphere of tomato fertilized by compost. Totally 26 composts were suppressive to bacterial wilt, while six composts stimulated the disease. The control efficiency was neither correlated with physicochemical properties (TC, TN, P and K, pH or GI) nor bacterial community of compost, but with rhizosphere bacterial community (r = 0.17, p = 0.016). The control efficiency was also positive correlated with taxa (Rhizobium, Aeromicrobium) known suppressive to R. solanacearum. The mushroom spent or cow manure, from which the two composts were 100% and 77% in control efficiencies against bacterial wilt respectively were subject to a pilot-scale composting reaction. The reproduced composts from mushroom spent or cow manure were only 57% and 23% effective on the control of bacterial wilt, respectively. The analysis of bacterial communities revealed that the relative abundances of R. solanacearum were 28.4% for the control, but only 7.8%-7.9% for compost fertilized tomatoes. The compost from mushroom spent also exerted a strong effect on rhizosphere bacterial community. Taken together, most composts were suppressive to bacterial wilt possibly also by modifying rhizosphere bacterial community towards inhibiting the colonization of R. solanacearum and selecting for beneficial genera of Proteobacteria, Bacteroidetes and Actinobacteria.

Co-inoculation of phosphate-solubilizing bacteria and phosphate accumulating bacteria in phosphorus-enriched composting regulates phosphorus transformation by facilitating polyphosphate formation.

This study aimed to explore the impact of co-inoculating phosphate-solubilizing bacteria (PSB) and phosphate accumulating bacteria (PAB) on phosphorus forms transformation, microbial biomass phosphorus (MBP) and polyphosphate (Poly-P) accumulation, bacterial community composition in composting, using high throughput sequencing, PICRUSt 2, network analysis, structural equation model (SEM) and random forest (RF) analysis. The results demonstrated PSB-PAB co-inoculation (T1) reduced Olsen-P content (1.4 g) but had higher levels of MBP (74.2 mg/kg) and Poly-P (419 A.U.) compared to PSB-only (T0). The mantel test revealed a significantly positive correlation between bacterial diversity and both bioavailable P and MBP. Halocella was identified as a key genus related to Poly-P synthesis by network analysis. SEM and RF analysis showed that pH and bacterial community had the most influence on Poly-P synthesis, and PICRUSt 2 analysis revealed inoculation of PAB increased ppk gene abundance in T1. Thus, PSB-PAB co-inoculation provides a new idea for phosphorus management.