Regulating pH and Phanerochaete chrysosporium inoculation improved the humification and succession of fungal community at the cooling stage of composting

Improving methane production and 4-chlorophenol removal in anaerobic digestion of corn straw by adding Phanerochaete chrysosporium and biochar under microaerobic conditions

The stable lignocellulose structure in the straw is the main obstacle for methane production during its anaerobic digestion, and the residual chlorophenols in the straw further increase the difficulty. In this study, the anaerobic digestion of corn straw containing 4-chlorophenol was enhanced by the addition of Phanerochaete chrysosporium and biochar. The results revealed that P. chrysosporium significantly increased the soluble COD concentration and total COD removal efficiency in the anaerobic digestion of corn straw, which initially contained a small amount of residual oxygen (4.1-4.5 mg/L). The accumulative methane production of the P. chrysosporium-coupled biochar (PC-BC) group and the PC group with P. chrysosporium alone were 232.9 ± 3.0 mL and 201.7 ± 5.1 mL, respectively, which were significantly higher than the control group (19.4 ± 1.0 mL) with the sterilized P. chrysosporium. The presence of biochar increased 4-CP removal rate to 93.3 %, which was 15.2 % higher than the control. Additionally, FTIR analysis indicated that the addition of P. chrysosporium and biochar enhanced the decomposition of lignocellulose structure. Moreover, the sludge capacitance and electron transfer capacity were highest in the PC-BC group. Also, microbial community analysis showed that biochar could enrich dechlorinating bacteria (e.g., Sedimentibacter) and electroactive microorganisms, which further enhanced dechlorination and methanogensis.

Microbial adaptation and genetic modifications for enhanced remediation in low-permeability soils

Low-permeability soils, characterized by fine texture and high clay content, pose significant challenges to traditional soil remediation techniques due to limited hydraulic conductivity, restricted nutrient flow, and reduced oxygen availability. These unique properties enable low-permeability soils to function as natural barriers in environmental protection; however, they also trap contaminants, making traditional remediation efforts challenging. This review synthesizes current knowledge on microbial adaptation and genetic engineering approaches that enhance the effectiveness of bioremediation in such environments. Key microbial adaptations, including anaerobic metabolism, extracellular enzyme production, and stress response mechanisms, allow individual microbes to adapt in low-permeability soils. Additionally, community-level strategies like microhabitat creation, biofilm formation, and functional redundancy further support microbial resilience. Advancements in genetic engineering now enable the modification of microbial traits-such as soil adhesion, nutrient utilization, and stress tolerance-to enhance bioremediation efficacy. Synthetic biology techniques further allow for the design of tailored microbial consortia that work cooperatively to degrade contaminants in complex soil matrices. This review highlights the integration of microbial and genetic engineering strategies, offering a comprehensive overview that informs current practices and guides future research in low-permeability soil remediation.

Metabolomics analysis of advancing humification mechanism in secondary fermentation of composting by fungal bioaugmentation

The aim of this study was to investigate the differential metabolites and core metabolic pathways caused by fungal bioaugmentation (pH regulation and Phanerochaete chrysosporium inoculation) in secondary fermentation of composting, as well as their roles in advancing humification mechanism. Metabolomics analyses showed that inoculation strengthened the expression of carbohydrate, amino acid, and aromatic metabolites, and pH regulation resulted in the up-regulation of the phosphotransferase system and its downstream carbohydrate metabolic pathways, inhibiting Toluene degradation and driving biosynthesis of aromatic amino acids via the Shikimate pathway. Partial least squares path model suggested that lignocellulose degradation, precursors especially amino acids and their metabolism process enhanced by the regulation of pH and Phanerochaete were the main direct factors for humic acid formation in composting. This finding helps to understand the regulating mechanism of fungal bioaugmentation to improve the maturity of agricultural waste composting.

Characteristics of humification, functional enzymes and bacterial community metabolism during manganese dioxide-added composting of municipal sludge

The aim of this study was to assess effects of MnO2 addition (CK-0%, T1-2% and T2-5%) on humification and bacterial community during municipal sludge (MS) composting. The results suggested that MnO2 addition inhibited the growth of Nitrospira but stimulated Nonomuraea, Actinomadura, Streptomyces and Thermopolyspora, facilitating the lignocellulose degradation and humification with the increase in organic matter degradation by 13.8%-19.2% and humic acid content by 10.9%-20.6%. Compared to CK, the abundances of exoglucanase (EC:3.2.1.91), endo-1,4-beta-xylanase (EC:3.2.1.136) and endomannanase (EC:3.2.1.78) increased by 88-99, 52-66 and 4-15 folds, respectively. However, 5%-MnO2 induced the enrichment of Mizugakiibacter that harms the environment of agricultural production. The addition of 2%-MnO2 was recommended for MS composting. Furthermore, metabolic function analysis indicated that MnO2 addition altered amino acid and carbohydrate metabolism, especially enhancing propanoate metabolism and butanoate metabolism but inhibiting citrate cycle. Structural equation modeling revealed that Nonomuraea and Actinomadura were the main drivers for lignocellulose degradation. This study provided theoretical guidance in regulating humification via MnO2 for MS composting.

The bioaugmentation effect of microbial inoculants on humic acid formation during co-composting of bagasse and cow manure

The effective degradation of recalcitrant lignocellulose has emerged as a bottleneck for the humification of compost, and strategies are required to improve the efficiency of bagasse composting. Bioaugmentation is a promising method for promoting compost maturation and improving the quality of final compost. In this study, the bioaugmentation effects of microbial inoculants on humic acid (HA) formation during lignocellulosic composting were explored. In the inoculated group, the maximum temperature was increased to 72.5 °C, and the phenol-protein condensation and Maillard humification pathways were enhanced, thus increasing the HA content by 43.85%. After inoculation, the intensity of the microbial community interactions increased, particularly for fungi (1.4-fold). Macrogenomic analysis revealed that inoculation enriched thermophilic bacteria and lignocellulose-degrading fungi and increased the activity of carbohydrate-active enzymes and related metabolic functions, which effectively disrupted the recalcitrant structure of lignocellulose to achieve a high humification degree. Spearman correlation analysis indicated that Stappia of the Proteobacteria phylum, Ilumatobacter of the Actinomycetes phylum, and eleven genera of Ascomycota were the main HA producers. This study provides new ideas for bagasse treatment and recycling and realizing the comprehensive use of resources.

Preparation of high-temperature and low-temperature-resistant solid microbial agent for cattle manure fermentation and effect on composting

We used microbiology and molecular biology techniques to screen out high-temperature and low-temperature-resistant saprobiotics for compost and prepared a compound fermentation bacteria agent to rapidly ferment cattle manure into high-quality organic fertilizer in low-temperature season. Conventional composting and high-throughput techniques were used to analyze the changes of physical and chemical indexes and biodiversity in the process of composting, from which high and low-temperature-resistant strains were obtained, and high-temperature and low-temperature-resistant solid composite bactericides were prepared and added to composting to verify the effects of composite bactericides on composting. The conventional composting cycle took 22 days, and the diversity of microflora increased first and then decreased. Composting temperature and microbial population were the key factors for the success or failure of composting. Two strains of high-temperature-resistant bacteria and six strains of low-temperature-resistant bacteria were screened out, and they were efficient in degrading starch, cellulose, and protein. The high-temperature and low-temperature-resistant solid bacterial agent was successfully prepared with adjuvant. The preparation could make the compost temperature rise quickly at low temperature, the high temperature lasted for a long time, the water content, C/N, and organic matter fell quickly, the contents of total phosphorus and total potassium were increased, and the seed germination index was significantly improved. Improve the composting effect. The solid composite bacterial agent can shorten the composting time at low temperature and improve the composting efficiency and quality.

Ore improver additions alter livestock manure compost ecosystem C:N:P stoichiometry

Deciphering the pivotal components of nutrient metabolism in compost is of paramount importance. To this end, ecoenzymatic stoichiometry, enzyme vector modeling, and statistical analysis were employed to explore the impact of exogenous ore improver on nutrient changes throughout the livestock composting process. The total phosphorus increased from 12.86 to 18.72 g kg-1, accompanied by a marked neutralized pH with ore improver, resulting in the Carbon-, nitrogen-, and phosphorus-related enzyme activities decreases. However, the potential C:P and N:P acquisition activities represented by ln(βG + CB): ln(ALP) and ln(NAG): ln(ALP), were increased with ore improver addition. Based on the ecoenzymatic stoiometry theory, these changes reflect a decreasing trend in the relative P/N limitation, with pH and total phosphorus as the decisive factors. Our study showed that the practical employment of eco stoichiometry could benefit the manure composting process. Moreover, we should also consider the ecological effects from pH for the waste material utilization in sustainable agriculture.

Electric field-assisted aerobic co-composting of chicken manure and kitchen waste: Ammonia mitigation and maturation enhancement

A low-voltage electric field assisted strategy is considered to be effective in improving compost effect of conventional chicken manure composting (CCMC), but it lacks a critical assessment of NH3 mitigation and suitability for complex initial materials. This study firstly constructed an electric field-assisted aerobic co-composting (EFAC) of chicken manure and kitchen waste to evaluate NH3 mitigation and compost maturity. The results showed that the NH3 emissions of EFAC were 48.73% lower than those of CCMC. The proposed mechanisms suggest that the combined effect of reduced acidity and electric field inhibited the activities and functions related to ammoniation and ammonia-nitrogen conversion. The germination index of EFAC was 54.29% higher than that of CCMC, due to the enhancement of compost maturation. This study demonstrates that the electric field-assisted strategy for co-composting has a broad potential to reduce ammonia emissions and enhance the disposal of complex feedstocks.