Exploring the dynamic of microbial community and metabolic function in food waste composting amended with traditional Chinese medicine residues.

The aim of this study was to explore the dynamic of microbial community and metabolic function in food waste composting amended with traditional Chinese medicine residues (TCMRs). Results suggested that TCMRs addition at up to 10% leads to a higher peak temperature (60.5 °C), germination index (GI) value (119.26%), and a greater reduction in total organic carbon (TOC) content (8.08%). 10% TCMRs significantly induced the fluctuation of bacterial community composition, as well as the fungal community in the thermophilic phase. The addition of 10% TCMRs enhanced the abundance of bacterial genera such as Acetobacter, Bacillus, and Brevundimonas, as well as fungal genera such as Chaetomium, Thermascus, and Coprinopsis, which accelerated lignocellulose degradation and humification degree. Conversely, the growth of Lactobacillus and Pseudomonas was inhibited by 10% TCMRs to weaken the acidic environment and reduce nitrogen loss. Metabolic function analysis revealed that 10% TCMRs promoted the metabolism of carbohydrate and amino acid, especially citrate cycle, glycolysis/gluconeogenesis, and cysteine and methionine metabolism. Redundancy analysis showed that the carbon to nitrogen (C/N) ratio was the most significant environmental factor influencing the dynamic of bacterial and fungal communities.

Insight into the microbial mechanisms for the improvement of composting efficiency driven by Aneurinibacillus sp. LD3.

This work explored the microbial mechanisms for the improvement of composting efficiency driven by thermotolerant lignin-degrading bacterium Aneurinibacillus sp. LD3 (LD3). Results showed that LD3 inoculant prolonged the thermophilic period by 4 days, improved the final content of humic acid, total phosphorus (TP), nitrogen, potassium and seed germination index. Inoculating LD3 enhanced the relative abundance of thermotolerant and phosphate-solubilizing microbes including the phyla of Proteobacteria, Bacteroidota, Firmicutes, and Actinobacteriota, and the genus of Bacillus, Thermoactinomyces, and Pseudomonas. Metabolic function analysis showed that sequences involved in carbohydrate and amino acid metabolism were boosted, while sequences associated with human disease were reduced after inoculating LD3. Spearman correlation analysis revealed that Aneurinibacillus has a significant positive correlation with temperature, TP, Bacillus, and Thermoactinomyces. This study provides useful information for understanding the microbial mechanisms of LD3 promoting composting efficiency, and reveals the tremendous potential of LD3 in the resource utilization of organic solid wastes.

Optimization of ultrasound-assisted water extraction of flavonoids from Psidium guajava leaves by response surface analysis.

Psidium guajava leaves are rich in health-promoting flavonoids compounds. For better utilization of the resource, the ultrasound-assisted aqueous extraction was investigated using Box-Behnken design under response surface methodology. A high coefficient of determination (R2 = 97.8%) indicated good agreement between the experimental and predicted values of flavonoids yield. The optimal extraction parameters to obtain the highest total flavonoids yield were ultrasonic power of 407.41 W, extraction time of 35.15 min, and extraction temperature of 72.69 °C. The average extraction rate of flavonoids could reach 5.12% under the optimum conditions. Besides, HPLC analysis and field emission scanning electron microscopy indicated that the ultrasonic treatment did not change the main component of flavonoids during extraction process and the higher flavonoids content was attributed by the disruption of the cell walls of guava particles. Thus, the extraction method could be applied successfully for large-scale extraction of total flavonoids from guava leaves.