Effect of moisture content on the evolution of bacterial communities and organic matter degradation during bioaugmented biogas residues composting

Fungal mediated production of novel metabolites of meloxicam and their tankyrase-2 inhibition potentials: an in silico study

The current study focuses on the isolation of a thermophilic fungus capable of biotransforming meloxicam to produce novel metabolites with potential tankyrase inhibitory properties. The isolated strain is identified as Rhizomucor pusillus, confirmed through both morphological and molecular methodologies. The biotransformation process was monitored using high-performance liquid chromatography (HPLC) in conjunction with a two-stage fermentation approach. Previous research, along with LC-MS/MS analyses, has successfully characterized the metabolites generated, providing structural validation. This fungus enabled the conversion of meloxicam into four metabolites: 5-hydroxy methyl meloxicam (M1), 5-carboxy meloxicam (M2), and two previously unreported metabolites (M3 and M4), under controlled conditions of pH 6.0 and a temperature of 40 °C over a 3-day shaking culture period. The fungal strain R. pusillus has demonstrated the ability to generate notable metabolites of meloxicam, particularly M1 and M2, as evidenced by research conducted on mammals. Moreover, in silico analyses have revealed the presence of two novel metabolites that may inhibit tankyrase-2. This finding indicates that R. pusillus possesses an enzymatic system comparable to that found in mammals, facilitating the environmentally sustainable and economically viable production of metabolites. Additionally, this strain is capable of synthesizing substantial amounts of metabolites that could potentially exhibit pharmacological effects.

Pre-biodrying treatment enhances lignin-related pathways with phenolic hydroxyls as reactive cores to accelerate humification during composting

The innovative biodrying-enhanced composting (BEC) process produces highly matured fertilizer within 10 d. To clarify the biodrying-accelerated humification mechanism, structural and molecular variations in humic acid (HA) during BEC were compared to those during 16-d bioaugmented mechanical composting without biodrying. Results showed that BEC produced HA with significantly higher aromaticity and molecular size (p < 0.01). More aromatic skeletons, mainly from biodrying-enhanced lignin decomposition (p < 0.05), contributed to HA aromatization. Reactive phenolic hydroxyls on these skeletons facilitated the binding of other humic precursors, promoting HA elongation. Microbial analysis indicated that Bacillus, Sinibacillus, and Issatchenkia, enriched by drastic heating and dehydration during days 0-3, participated in lignin decomposition. Saccharomonospora, Georgenia, Oceanobacillus, Nigrospora, Kluyveromyces, and Aspergillus contributed to HA elongation during the maturation phase (days 3-9). This study's findings that biodrying enhanced lignin-related humification pathways by enriching functional microorganisms provides a theoretical foundation for further improving compost humification efficiency.

Enhancing C and N turnover, functional bacteria abundance, and the efficiency of biowaste conversion using Streptomyces-Bacillus inoculation

Microbial inoculation plays a significant role in promoting the efficiency of biowaste conversion. This study investigates the function of Streptomyces-Bacillus Inoculants (SBI) on carbon (C) and nitrogen (N) conversion, and microbial dynamics, during cow manure (10% and 20% addition) and corn straw co-composting. Compared to inoculant-free controls, inoculant application accelerated the compost's thermophilic stage (8 vs 15 days), and significantly increased compost total N contents (+47%) and N-reductase activities (nitrate reductase: +60%; nitrite reductase: +219%). Both bacterial and fungal community succession were significantly affected by DOC, urease, and NH4+-N, while the fungal community was also significantly affected by cellulase. The contribution rate of Cupriavidus to the physicochemical factors of compost was as high as 83.40%, but by contrast there were no significantly different contributions (∼60%) among the top 20 fungal genera. Application of SBI induced significant correlations between bacteria, compost C/N ratio, and catalase enzymes, indicative of compost maturation. We recommend SBI as a promising bio-composting additive to accelerate C and N turnover and high-quality biowaste maturation. SBI boosts organic cycling by transforming biowastes into bio-fertilizers efficiently. This highlights the potential for SBI application to improve plant growth and soil quality in multiple contexts.

Insight into bacterial role attribution in dissolved organic matter humification during rice straw composting with microbial inoculation

This study aims to investigate the effect of microbial role distribution in microbial carbon pumps on dissolved organic matter (DOM) humification during rice straw composting with microbial inoculation. Three composting groups were designed, named CK (control), B4 (with Bacillus subtilis, OR058594) and Z1 (with Aspergillus fumigatus, AF202956.1). As a result of inoculation, the composition of microbial communities was changed, so that the microorganisms that promoted DOM humification were concentrated in the responders in the microbial carbon pump. DOM was divided into three components in three composting treatments: C1, C2 and C3. After inoculation with Bacillus subtilis, the C2 component was significantly affected, while after inoculation with Aspergillus fumigatus, the C3 component was significantly affected. The results of physicochemical factors affecting the transformation of DOM fluorescence components indicated that C1, C2 and C3 were related to the abundance of the cellulose-degrading enzyme-encoding gene GH7 in CK and B4 composting. However, the C2 was susceptible to organic matter in Z1 composting. This study explored the distribution of microbial communities from a new perspective, which provided new information for analyzing DOM humification and treating agricultural straws to achieve clean conditions for environmental friendliness.

Available sulfur and phosphorus transformation mechanism and functional microorganisms during sheep manure composting on Qinghai-Tibet Plateau under two moisture contents

Understanding the mechanisms of sulfur and phosphorus transformation during composting is important for improving compost fertility. This study aims to investigate the microbial mechanism of available sulfur and phosphorus transformation during sheep manure composting under different moisture contents (45%: M45 and 60%: M60) on the Qinghai-Tibet Plateau using metagenomics technology. The results showed that the final available sulfur and phosphorus contents of M45 were 11% and 13% higher than those of M60, respectively. M45 enhanced sulfur oxidation, sulfate reduction, and thiosulfate disproportionation. These steps were significantly positively correlated with available sulfur, and Pseudomonas, Thermobifida, Luteimonas, Brevibacterium, Planifilum, and Xinfangfangia were the main participants. Available phosphorus was significantly positively correlated with polyphosphate degradation and inorganic P solubilization, and the main participants in these steps were Luteimonas, Brachybacterium, Corynebacterium, Jeotgalicoccus, Microbacterium, Streptomyces, and Pseudoxanthomonas. These findings reveal the microbial mechanisms of available and phosphorus transformation during composting at two moisture contents.

Effects of turning frequency on fermentation efficiency and microbial community metabolic function of sheep manure composting on the Qinghai-Tibet Plateau

This study explored the effects of turning frequency on fermentation efficiency and microbial metabolic function of sheep manure composting on the Qinghai-Tibet Plateau (QTP). Five treatments with different turning frequencies were set up in this study: turning every 1 day (T1), 2 days (T2), 4 days (T3), 6 days (T4), and 8 days (T5). Results showed that the high temperature period for T1 and T5 lasted only 4 days, while that for T2-T4 lasted more than 8 days. The germination index of T1 and T5 was lower than 80%, while that of T2-T4 was 100.6%, 97.8%, and 88.6%, respectively. This study further predicted the microbial metabolic function of T2-T4 using the bioinformatics tool PICRUSt2 (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) and determining the activities of various functional enzymes. The results showed that carbohydrate metabolism, protein metabolism, and nucleotide metabolism were the main metabolic pathways of microorganisms, and that T2 increased the abundance of functional genes of these metabolic pathways. The activities of protease, cellulase, and peroxidase in T2 and T3 were higher than those in T4, and the effect of T2 was more significant. In conclusion, turning once every 2 days can improve the quality of sheep manure compost on the QTP.