Changes of fungal diversity in fine coal gasification slag amendment pig manure composting

Resource utilization of decarbonized coal gasification slag in soil quality improvement: New insights into microbial community composition and environmental risk assessment

Decarbonized coal gasification slag (DCGS) is a coal-based solid waste generated from raw coal through the processes of gasification and decarbonization. However, the excessive production of DCGS has caused large-scale environmental problems and seriously affected the sustainable development of coal chemical enterprises. It's urgent to explore a high-value utilization approach. Here, a field trial was conducted to evaluate the feasibility of soil amendment using DCGS in a sandy soil. The 16S rRNA gene sequencing, soil quality approach and partial least squares path modeling were used to assess the responses of soil properties and relative forage value (RFV) of Leymus chinensis to DCGS addition in soil-plant-microbe system. Results showed that DCGS addition significantly increased soil pH, soil organic carbon (22.4 %), alkaline phosphatase (ALP) enzyme activity (16.5 %) and α-diversity of bacterial communities (1.37 %). Soil microbial biomass CNP in DCGS1, DCGS2, DCGS3 and DCGS4 treatments were 10.7 %, 21.3 %, 44.8 % and 69.1 % higher than control check (CK) treatment, respectively. Our study emphasized the β-diversity of bacterial communities and topological parameters of microbial co-occurrence networks were significantly altered after DCGS addition. Ultimately, higher soil quality and RFV of Leymus chinensis were obtained in DCGS addition treatments rather than the CK treatment (p < 0.01). Moreover, soil pH and p_Methylomirabilota were identified as the crucial factors affecting soil quality, while soil ALP and p_Entotheonellaeota were key factors affecting RFV of Leymus chinensis according to Mantel test. Our result further evidenced that there were relatively low ecological risk level after DCGS addition (Ecological Risk Index < 150), thus DCGS addition was considered as a potential method in improving soil quality. Taking into account the impact of DCGS addition on soil microbial community, soil quality, and ecological safety, the recommended application rate for sandy soil is 60 t·ha-1 (DCGS3). Our findings elucidate that soil amendment with DCGS not only enhance soil quality and RFV of Leymus chinensis, but also provide potential possibility for safe and environmentally friendly utilization of DCGS. These findings deepened our understanding of sustainable development and efficient management of DCGS.

The impact of Ricinus straw on tomato growth and soil microbial community

Returning straw can alter the soil microbial community, reduce the occurrence of soilborne diseases, and promote plant growth. In this study, we aimed to evaluate the effects of Ricinus straw on tomato growth and rhizosphere microbial community. We carried out microcosm experiments to investigate the effects of Ricinus straw with different dosages (0, 1, and 3%) on tomato dry biomass and rhizosphere bacterial and fungal communities. The results indicated that the dry biomass of tomato seedlings with 1% addition of Ricinus straw increased by 53.98%. In addition, Ricinus straw also changed the abundance, diversities, and composition of tomato rhizosphere microbial communities. In detail, the addition of 1% Ricinus straw increased the relative abundance of putative beneficial bacteria and fungi in straw decomposition, such as Ramlibacter sp., Azohydromonas sp., Schizothecium sp., and Acaulium sp., and decreased the relative abundance of Fusarium sp. Meanwhile, Ricinus straw inhibited the growth of putative pathogenic microorganisms. The correlation analysis showed that the changes in fungal community operational taxonomic units stimulated by the addition of Ricinus straw may play a crucial positive regulatory role in tomato growth. Finally, the representative fungal strain Fusarium oxysporum f. sp. Lycopersici (FOL), named TF25, was isolated and cultured. We found that Ricinus straw extract inhibited the growth of TF25 in an in vitro experiment with an inhibition rate of 34.95-51.91%. Collectively, Ricinus straw promoted plant growth by changing the rhizosphere microbial community composition and inhibiting FOL growth, which provides new evidence for understanding the improvement of key microorganism composition in improving crop growth and the sustainability of agriculture.

Performance evaluation and microbial community succession analysis of co-composting treatment of refinery waste activated sludge

Refinery waste activated sludge (RWAS) is riched in organic matter with energy recovery value, while unique petroleum components in RWAS may pose challenges to the recycling process. Aerobic composting technology is an effective means of organic solid waste resource treatment, which can convert organic solid waste into fertilizer for agriculture. This study explores the effect of petroleum components on the performance of RWAS composting by co-composting it with chicken manure. The results showed that more than 65% of petroleum was removed by aerobic composting. After composting, germination index (GI) exceeded 80%, and a humic acid to fulvic acid ratio (HA/FA) was greater than 1. These results signified that the petroleum components slightly affect the harmless and recycling of RWAS. The microbial community succession found that Firmicutes (54.11-91.96%) and Ascomycota (82.35-97.21%) emerged as the dominant phyla during the thermophilic phase of composting. Thermobifida, norank_f__Limnochordaceae and Kernia were the key microorganism in the degradation of petroleum and the humification of composting, and reduced the phytotoxicity of composting products. Redundancy analysis found that the degradation of petroleum was conducive to the formation of humic acid. These findings indicate that aerobic composting technology can remove petroleum components in RWAS and convert them into composted fertilizers, providing key technical support for managing RWAS in a sustainable and environmentally friendly manner.

Manure enriched with nitrogen derived from high-protein food waste in a large dining facility

Food waste (FW) from large dining facility has been a pressing environmental challenge in China recently. This study developed an innovative species-specific feeding strategy for producing pigeon meat and excellent manure from FW. Adding FW to the feed of pigeons significantly increased their feed intake and promoted their growth although the pigeons showed a strong aversion to the FW. We produced a "super manure" with exceptionally high nitrogen (N) content (mean = 10.77 % on a dry basis, 8.04-12.57 %, n = 264) by feeding slowly-growing pigeon species (Columba livia vs. and Caoge Huzhou 11) with protein-high commercial feed and FW. A significant negative relationship between the N and carbon (C) contents in the pigeon manure was found, with C depletion higher than N depletion. Furthermore, the N content in the anaerobic composting (AnC) manure was 29.16 % higher than that in the FW. Fourier transform infrared (FT-IR) analysis and stable isotopes δ13C and δ15N in the manure clearly identified the transformations of nutrients during pigeon feeding and the AnC process. This study opens a path for producing N-high manure using protein-high food waste.

Humification and fungal community succession during pig manure composting: Membrane covering and mature compost addition

The objective of this study was to elucidate the combined effect of a semi-permeable membrane (M) and mature compost (MC) on humification and fungal community succession in pig manure composting. Compared with the control, the concentrations of humic substances (HSs) increased by 44.54 % (M + 15 % MC) and 43.90 % (M). During the thermophilic phase, Aspergillus (67.26 %) was the dominant genus in the M + 15 % MC treatment. Membrane covering increased the relative abundance (RA) of other phyla (except for Ascomycetes and Basidiomycetes) on the 14th day and Basidiomycetes on the 80th day in M treatment. Humic acid, HSs were positively correlated with the RA of genera Myceliophthora, Kernia, and Mycothermus. Myceliophthora was the key genus in the M + 15 % MC treatment on the 80th day. The results showed that 15 % MC addition under membrane covering optimizes the quality of composting products.

Microbiome science of human excrement composting

Linear waste management systems are unsustainable and contribute to environmental degradation, economic inequity, and health disparities. Among the array of environmental challenges stemming from anthropogenic impacts, the management of human excrement (human feces and urine) stands as a significant concern. Over two billion people do not have access to adequate sanitation, signifying a global public health crisis. Composting is the microbial biotechnology aimed at cycling organic waste, including human excrement, for improved public health, agricultural productivity and safety, and environmental sustainability. Applications of modern microbiome omics and related technologies have the capacity to support continued advances in composting science and praxis. In this article, we review literature focused on applications of microbiome technologies to study composting systems and reactions. The studies we survey generally fall into the categories of animal manure composting, biosolids composting, and human excrement composting. We review experiments utilizing microbiome technologies to investigate strategies for enhancing pathogen suppression and accelerating the biodegradation of organic matter. Additionally, we explore studies focused on the bioengineering potential of microbes as inoculants to facilitate degradation of toxins, such as pharmaceuticals or per- and polyfluoroalkyl substances. The findings from these studies underscore the importance of advancing our understanding of composting processes through the integration of emerging microbiome omics technologies. We conclude that work to-date has demonstrated exciting basic and applied science potential from studying compost microbiomes, with promising implications for enhancing global environmental sustainability and public health.

Influence of biochar on succession of fungal communities during food waste composting

This study aims to examine the effects of biochar on fungal dynamics during food waste composting. The different dosage of wheat straw biochar from 0 to 15% (0%, 2.5%, 5%, 7.5%, 10%, and 15%) were used as an additive to composting and examined for 42 days. The results showed that Ascomycota (94.64%) and Basidiomycota (5.36%) were the most dominant phyla. The most common fungal genera were Kluyveromyces (3.76%), Candida (5.34%), Trichoderma (2.30%), Fusarium (0.46%), Mycothermus-thermophilus (5.67%), Trametes (0.46%), and Trichosporon (3.38%). The average number of operational taxonomic units were 469, with the greatest abundance seen in the 7.5% and 10% treatments. Redundancy analysis revealed that different concentrations of biochar applied treatments have significantly distinct fungal communities. Additionally, correlation analyses of fungal interactions with environmental elements, performed through a heatmap, also indicate a distinct difference among the treatments. The study clearly demonstrates that 15% of biochar has a positive impact on fungal diversity and improves the food waste composting.

Multitudinous components recovery, heavy metals evolution and environmental impact of coal gasification slag: A review

In recent years, the coal gasification industry has rapidly developed, becoming one of the most promising technologies in the advanced and clean coal chemical industry. As a result, the annual emission of coal gasification fine slag (CGFS) has continuously increased. The present situation of CGFS is regarded as a notorious waste in gasification plants and is rudely landfilled or deposited in slag yards, which leads to a large waste of land resources, the release of dangerous elements, and numerous pollution problems. Although CGFS is classified as industrial solid waste, its unique physical and chemical properties make it a valuable resource that cannot be overlooked. This paper focuses on the resource utilization technology and environmental impact of CGFS. The resource utilization of different components of CGFS has realized the evolution from waste to valuable substances. Moreover, during the disposal and utilization of CGFS, its environmental effects cannot be ignored. The main problems and future research directions are also further proposed. Efforts should be focused on the challenges of the technology, cost, and environmental protection in the application process to achieve industrial application, and ultimately committed to sustainable and green development goals, and promote the sustainable management and conservation of resources.

Mechanisms and effects of novel ammonifying microorganisms on nitrogen ammonification in cow manure waste composting

It is essential to reduce nitrogen losses and to improve nitrogen conversion during organic waste composting because of environmental protection and sustainable development. To reveal newly domesticated ammonifying microorganisms (AM) cultures on the ammonification and nitrogen conversion during the composting, the screened microbial agents were inoculated at 5 % concentration (in weight basis) into cow manure compost under five different treatments: sterilized distilled water (Control), Amm-1 (mesophilic fungus-F1), Amm-2 (mesophilic bacterium-Z1), Amm-3 (thermotolerant bacterium-Z2), and Amm-4 (consortium: F1, Z1, and Z2), and composted for 42 days. Compared to control, AM inoculation prolonged the thermophilic phases to 9-19 days, increased the content of NH4+-N to 1.60-1.96 g/kg in the thermophilic phase, reduced N2O and NH3 emissions by 22.85-61.13 % and 8.45-23.29 %, increased total Kjeldahl nitrogen, and improved cell count and viability by 12.09-71.33 % and 66.71-72.91 %. AM was significantly associated with different nitrogen and microbial compositions. The structural equation model (SEM) reveals NH4+-N is the preferable nitrogen for the majority of bacterial and fungal growth and that AM is closely associated with the conversion between NH3 and NH4+-N. Among the treatments, inoculation with Amm-4 was more effective, as it significantly enhanced the driving effect of the critical microbial composition on nitrogen conversion and accelerated nitrogen ammonification and sequestration. This study provided new concepts for the dynamics of microbial in the ammonification process of new AM bacterial agents in cow manure compost, and an understanding of the ecological mechanism underlying the ammonification process and its contribution to nitrogen (N) cycling from the perspective of microbial communities.

External static magnetic field potentiates the reduction of antibiotic resistance genes during swine manure composting

Livestock and poultry manure are repositories of antibiotic resistance genes (ARGs). Accumulating evidence suggests that composting is an important way to effectively attenuate ARGs, but how to reinforce the reduction in ARGs during composting needs to be further investigated. This study explored the influence of an external static magnetic field on ARG mitigation enhancement during swine manure composting. The results showed that a total of 12 high-risk ARGs were identified. A relatively high magnetic field intensity (14.81 mT) was more effective in reducing the abundance of high-risk ARGs, and the removal rate was 20.66-100 %. It also reduced the abundance of 27.14 % of integrons, 79.44 % of insertion sequences, and 8.78 % of plasmids. Partial least squares path modeling showed that a relatively high magnetic field intensity treatment promoted the reduction in ermB by reducing the abundance of Phascolarctobacterium, Streptococcus, and insertion sequences. It also mitigated sul1 expression by reducing the abundance of Acinetobacter and integrons, and it mitigated tetM expression by decreasing Lactobacillus, Streptococcus, insertion sequences, and plasmids. These findings demonstrate that an external static magnetic field is an effective method for intensifying the reduction in ARGs, providing a feasible reference for controlling the potential ARG risk of organic waste composting.

Phosphorus functional microorganisms and genes: A novel perspective to ascertain phosphorus redistribution and bioavailability during copper and tetracycline-stressed composting

There is limited information on the phosphorus availability under copper and tetracycline-amended composting: Insights into microbial communities and genes. Thus, this work investigated the phosphorus redistribution and transformation, illustrated the variation in microbial communities and genes, and ascertained the multiple action-patterns among which within copper and tetracycline-amended composting. Phosphorus bioavailability reduced by 8.96 % ∼ 13.10 % due to the conservation of Ex-P to Ca-P. Copper and tetracycline showed a significant effect on fungal succession, but not to bacteria, as well as inhibited the phosphorus functional genes in fungal communities, while accelerated it in bacterial communities. Under the copper/tetracycline-stressed conditions, bacterial Firmicutes could promote the mineralization of organic phosphorus, and bacterial Proteobacteria might facilitate the dissolution of inorganic phosphorus. These findings could provide theoretical guidance for the further research on phosphorus bioavailability ascribed to microbial communities and genes.

Exploring the impact of biochar supplement on the dynamics of antibiotic resistant fungi during pig manure composting

The purpose of this study was to investigate antibiotic resistant fungal (ARF) communities in pig manure (PM) composting employing two different biochar (coconut shell-CSB and bamboo biochar-BB) as amendment. Three treatments (Control, 10% CSB and 10% BB) were designed and indicated with T1 to T3. Experimental results declared that the fungal abundance significantly reduced among the both biochar applied treatments but three dominant phyla Ascomycota, Basidiomycota and Mucoromycota were still relatively greater abundance present. There were significant differences (p < 0.05) in the relative abundance and diversity of fungi among all three treatments. Interestingly, biochar addition regulated the overall fungal community in final compost. Compared with the control group, the abundance of fungi was positively mobilized, and especially CSB showed a better effect. Conclusively, biochar has potential to inhibit and reduce the ARGs population and mobility in compost. Thus, these findings offer new insight to understand the succession of ARFs during PM composting.

Synergistic influence on microbial communities ascribed to copper and tetracycline during aerobic composting: Insights into bacterial and fungal structures

There are a considerable number of discussions aimed at analyzing microbial communities and their functions during the composting process. However, microbial succession under copper (Cu) and tetracycline (TCH)-stressed conditions has received less attention. Thus, this work analyzed the bacterial and fungal structures with high-throughput sequencing in Cu/TCH-amended composting (Cu: 0, 100, and 500 mg/kg; TCH: 0, 50, and 300 mg/kg), and the dominating controls on microbial diversity were identified using redundancy analysis (RDA) and structural equation models (SEMs). Low-concentration Cu increased the peak temperature (57°C) at the thermophilic phase. Composting phase-derived changes in bacterial and fungal communities were significant, while Cu and TCH showed a remarkable influence on fungi but not on bacteria. Cu and TCH inhibited Firmicutes' activity while promoting Actinobacteriota growth. Low-concentration Cu and TCH had a negative effect on Basidiomycota in the thermophilic phase and a positive influence on Chytridiomycota in the mature phase. TOC and TN were primary controls on the changes in microbial communities. NH4+-N and NO3--N were more beneficial to fungi with a contribution proportion of 42.13 and 16.85%, respectively. These findings could provide theoretical guidance for the directional research on microbial inoculants.

Variation in community structure and network characteristics of spent mushroom substrate (SMS) compost microbiota driven by time and environmental conditions

Global mushroom production is growing rapidly, raising concerns about polluting effects of spent mushroom substrate (SMS) and interest in uses in composts. In this study, SMS composting trials and high-throughput sequencing were carried out to investigate to better understand how the structure, co-occurrence patterns, and functioning of bacterial and fungal communities vary through compost time and across environmental conditions. The results suggested that both bacterial and fungal microbiota displayed significant variation in community composition across different composting stages. Enzyme activity levels showed both directional and fluctuating changes during composting, and the activity dynamics of carboxymethyl cellulase, polyphenol oxidase, laccase, and catalase correlated significantly with the succession of microbial community composition. The co-occurrence networks are "small-world" and modularized and the topological properties of each subnetwork were significantly influenced by the environmental factors. Finally, seed germination and seedling experiments were performed to verify the biosafety and effectiveness of the final composting products.

Using One-Step Acid Leaching for the Recovering of Coal Gasification Fine Slag as Functional Adsorbents: Preparation and Performance

Coal gasification fine slag (FS), a kind of by-product of coal chemical industry, was recovered for the preparation of functional adsorbents by acid leaching process, which was orthogonally optimized by HCl, HNO₃, HF, HAc, and H₂SO₄. Methylene blue (MB) was used to evaluate the performance of functional adsorbents. The results demonstrated that 57.6% of the leaching efficiency (R_LE) and 162.94 mg/g of adsorption capacity (C_AC) of MB were achieved under the optimal conditions of HNO₃ of 2.0 mol/L, acid leaching time of 2.0 h, and acid leaching temperature of 293K. The detections on X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and BET surface area (SBET) indicated that the synthesized functional adsorbents were characterized by mesoporous materials. The good fitting of adsorption process using pseudo-second-order and Langmuir models demonstrated that the chemisorption contributed to MB removal. The results of thermodynamics further revealed that the adsorption process of MB occurred spontaneously due to the exothermic properties. The work is expected to develop a novel and cost-effective strategy for the safe disposal of FS, and potentially offer an alternative pathway to increase the additional value for the coal chemical industry.

Recent trends and advances in composting and vermicomposting technologies: A review

Composting technologies have come a long way, developing from static heaps and windrow composting to smart, artificial intelligence-assisted reactor composting. While in previous years, much attention has been paid to identifying ideal organic waste streams and suitable co-composting candidates, more recent efforts tried to determine novel process-enhancing supplements. These include various single and mixed microbial cultures, additives, bulking agents, or combinations thereof. However, there is still ample need to fine-tune the composting process in order to reduce its impact on the environment and streamline it with circular economy goals. In this review, we highlight recent advances in integrating mathematical modelling, novel supplements, and reactor designs with (vermi-) composting practices and provide an outlook for future developments. These results should serve as reference point to target adjusting screws for process improvement and provide a guideline for waste management officials and stakeholders.

Magnesite driven the complementary effects of core fungi by optimizing the physicochemical parameters in pig manure composting

The effects of magnesite (MS) on fungi communities and the core fungi complementarity during pig manure (PM) composting were explored. Different dosage of MS [0% (T1), 2.5% (T2), 5% (T3), 7.5% (T4) and 10% (T5)] as amendments mixed with PM for 42 days composting. The results showed the dominant of phyla were Ascomycota (78.87%), Neocallimastigomycota (41.40%), Basidiomycota (30.81%) and Aphelidiomycota (29.44%). From day 7 to 42, the abundance of Ascomycota and Aphelidiomycota were increased from 7.75% to 42.41% to 57.27%-78.87% and 0-0.70% to 11.73%-29.44% among all treatments. Nevertheless, the phyla abundance of Neocallimastigomycota and Basidiomycota decreased from day 7 to 42. The co-occurrence network indicated that the high additive amendment could enhance the core fungi complementarity effects capacity. The 10% MS addition was a promisable candidate to optimum fungal communities, and causing a better compost quality. This study illustrated the potential and fungi communities changing of MS as additives in composting.

Co-composting with cow dung and subsequent vermicomposting improve compost quality of spent mushroom

In order to determine a feasible degrading process for spent mushroom (SMS) with high lignin content, the present work used cow dung (CD), SMS, and a mixture of CD and SMS as substrates and evaluated the effects of vermicomposting on the microflora and the quality of composting products. Bacterial (R² = 0.548, P = 0.001) and fungal (R² = 0.314, P = 0.005) community both were different between composting and vermicomposting. Vermicomposting and substrates affected enzyme activities indirectly by affecting ammonium, pH, total carbon, richness, and bacterial community composition. These results suggested that appropriate regulation of environmental factors may increase microbial activity. An increase in ion-exchange capacity (up to 139.8%), pH (6.9%), and nitrate (71.1%) and a decrease in total carbon (31.2%) and carbon/nitrogen ratio (32.1%) in vermicomposting indicated that earthworms could further improve product quality. Co-composting with CD and integrated subsequent vermicomposting efficiently promoted the maturity of SMS.

Predicting the humification degree of multiple organic solid waste during composting using a designated bacterial community

Microbes are the drivers for disposing of organic solid waste (OSW) during aerobic fermentation. Notwithstanding, the significance of microbes is underestimated in numerous studies on aerobic fermentation product assessments. Here, we investigated the humification degree (HD), and the humic acid content was assessed in terms of the bacterial community. The bacterial communities were useful indicators for making predictions and even correctly determined the categories of OSWs with 94% accuracy. The bacterial codes can also provide a better prediction of HD. Our results demonstrate that the bacteria code is a reliable biological method to assess HD effectively. Bacterial codes can be used as ecological and biological indicators to evaluate the quality of aerobic fermentation of different materials.

Potential of biochar integrated manganese sulfate for promoting pig manure compost humification and its biological mechanism

This study aimed to clarify the effect of the integrated addition of different proportions of biochar (0 and 5%) and MnSO4 (0, 0.25%, and 0.50%) to pig manure compost. The results indicated the integrated use of biochar (BC) and Mn2+ advanced the compost humification. In particular, the integrated use of 0.50% Mn2+ and 5% BC showed higher total organic carbon degradation (20.67%) and humic acid production (81.26 g kg-1) than other treatments. Microbial community analysis showed the integrated use of BC and Mn2+ regulated the diversity and community structure of organic matter-mineralizing microbes by maintaining the relative abundance of bacteria Firmicutes (54.62%) and Proteobacteria (38.05%) at high levels during the thermophilic period and boosting those of the fungi of Ascomycota (58.91%) and Actinobacteria (15.60%) during the maturity period of composting. This study illustrated the potential and biological mechanisms of integrating BC and Mn2+ as additives in compost humification.

The Quality Analysis and Deterioration Mechanism of Liquid Egg White during Storage

The quality of liquid egg white (LEW) during storage is critical for the development of the egg industry. In order to effectively control its storage quality, the effects of packaging materials and storage conditions on the quality of LEW were investigated. High-throughput sequencing (HTS) was applied to explore changes in bacterial population proportions and microflora in the spoilage of LEW. The shelf life of LEW packaged with glass (LEW-PG), plastic (LEW-PP), and tinplate (LEW-PT) was preliminarily determined to be 8, 5, and 7 days, respectively. LEW-PG possessed superior sensory scores (65) and L values (87.5), and a lower growth rate of total volatile basic nitrogen (TVB-N) content among the three samples on the last day of shelf life, and was chosen for further study. During 24 days of storage, the sensory scores of the LEW-PG in 10 °C and 4 °C groups decreased by 32.7% and 25.7%, respectively. There was no significant difference in foaming properties of LEW-PG between the 10 °C and 4 °C groups (p > 0.05). HTS analysis showed that the abundance of species composition in the 10 °C samples was higher than that in the 4 °C samples, though the latter possessed a higher community diversity. At the genus level, the dominant bacteria in the 10 °C group were Pseudomonas (21.79%), others (19.21%), and Escherichia (11.21%), while others (37.5%), Escherichia (30.40%), and Bifidobacterium (17.72%) were highly abundant in the 4 °C samples. It is hoped that this study could provide theoretical support for quality control of LEW during storage.

Tetracycline hydrochloride-stressed succession in microbial communities during aerobic composting: Insights into bacterial and fungal structures

Available information that whether antibiotics affect the succession in microbial communities during aerobic composting remains limited. Thus, this work investigated the dynamic changes in bacterial and fungal structures during aerobic composting amended with tetracycline hydrochloride (TCH: 0, 50, 150 and 300 mg kg^-1). Composting phases significantly affected bacterial and fungal communities, but only fungi strongly responded to antibiotics, while bacteria did not. Firmicutes, Proteobacteria, Bacteroidota and Actinobacteriota were primary bacterial phylum. Neocallimastigomycota was dominant fungal phylum at temperature-heating phase, then Basidiomycota and Ascomycota became main fungal phylum at thermophilic and temperature-colling phases. Low TCH concentration promoted Chytridiomycota growth, while high TCH concentration inhibited mostly fungal activity in TCH-amended composting. Nitrogen species were critical factors controlling the succession in bacterial and fungal communities during composting process. These results cast a new light on understanding about microbial function during aerobic composting.

Bacterial and fungal community dynamics during different stages of agro-industrial waste composting and its relationship with compost suppressiveness

Composting is an advantageous and efficient process for recycling organic waste and producing organic fertilizers, and many kinds of microorganisms are involved in obtaining quality compost with suppressive activity against soil-borne pathogens. The aim of this work was to evaluate the main differences in the effects of three composting piles on the whole bacterial and fungal communities of baby-leaf lettuce crops and to determine the specific communities by high-throughput sequencing related to suppressiveness against the soil-borne plant pathogen Pythium irregulare- (P. irregulare). Compost pile A was composed of 47% vineyard pruning waste, 34% tomato waste and 19% leek waste; pile B was composed of 54% vineyard pruning waste and 46% tomato waste; and pile C was composed of 42% vineyard pruning waste, 25% tomato waste and 33% olive mill cake. The temperature and the chemical properties of the piles were monitored throughout the composting process. In addition, the potential suppressive capacity of the three composts (C_A, C_B and C_C) against P. irregulare in baby-leaf lettuce was assessed. We found that the bacterial community changed according to the composting phases and composting pile and was sensitive to chemical changes throughout the composting process. The fungal community, on the other hand, did not change between the composting piles and proved to be less influenced by chemical properties, but it did change, principally, according to the composting phases. All composts obtained were considered stable and mature, while compost C_C showed higher maturity than composts C_A and C_B. During composting, the three piles contained a greater relative abundance of Bacterioidetes, Proteobacterias and Actinobacterias related to the suppression of soil-borne pathogens such as Pythium irregulare. Composts C_A and C_B, however, showed higher suppressiveness against P. irregulare than compost C_C. Deeper study showed that this observed suppressiveness was favored by a higher abundance of genera that have been described as potential suppressive against P. irregulare, such as Aspergillus, Penicillium, Truepera and Luteimonas.

Distribution of heavy metal resistant bacterial community succession in cow manure biochar amended sheep manure compost

The aim of this investigation was to study the effects of cow manure biochar (CMB) on the distribution of heavy metal resistant bacterial (HMRB) community succession during sheep manure (SM) composting. The experiments were conducted with six different ratio of CMB (0%(T1), 2.5%(T2), 5%(T3),7.5%(T4),10%(T5) and 12%(T6)onadryweightbasis) and 0% is used as control. The results showed that the most dominant phylum were Proteobacteria (40.89%-5.65%) and Firmicutes (0.16%-93.18%), and 7.5% CMB mixed with sheep manure for best results. Thus, significant correlation was noticed among the analyzed physicochemical factors, gaseous emission and bacterial phylum in used 7.5-10% CMB applied for SM composting. Overall, the application of biochar increased the diversity of the bacterial community and promoted the degradation of organic matter. In addition, 7.5-10% CMB applied treatments showed greater immobilization of HMRB community succession during SM composting.