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Highlights • Earthworm casts and zeolite improved the thermophilic temperature of compost. • Earthworm casts and zeolite influenced the succession of bacterial community. • Bacterial community and function were related to temperature and NH 4 + content. Abstract Succession and metabolism functions of bacterial communities were determined in maize straw composting with earthworm casts and zeolite addition by using high-throughput sequencing, Biolog and PICRUSt. Results showed that earthworm casts and zeolite addition increased the temperature, decreased NH 4 + contents and affected bacterial community structure. The relative abundances of Firmicutes and Betaproteobacteria increased with earthworm casts and zeolite addition in the late stage. The abundances of genes related to carbohydrate metabolism, amino acid metabolism, and energy metabolism were increased by these two additives in the early stage, but decreased in the late stage. Network analysis demonstrated that members of Bacillaceae were identified as the keystone taxa. Temperature showed negative relationship with Georgenia , while NH 4 + exhibited positive associations with Georgenia , Devosia , Ruania and Mycobacterium. These results indicated that earthworm casts and zeolite addition benefitted the keystone species and enhanced the metabolism capacity of bacterial community, thereby improved the quality of compost. [ABSTRACT FROM AUTHOR]

Highlights • Biochar addition increased thermophilic temperature and extended the high temperature period of compost. • Biochar addition enriched more amounts of specific bacterial taxa related to decomposition of organic matter. • The microbial co-occurrence pattern and keystone taxa were observed during composting. • DOC and TN were the key environmental factors for community succession. Abstract High-throughput sequencing and network analysis were used to investigate the dynamic changes and the effects on bacterial community structures in green waste compost after biochar addition. Biochar addition led to higher thermophilic temperatures and total nitrogen (TN) concentrations and a longer thermophilic period compared with no biochar addition. Biochar also greatly influenced the composition of the bacterial community. Nitriliruptoraceae and Bacillaceae abundances increased in the poultry manure after biochar treatment, and Alcaligenaceae , Rhodispirillaceae and Xanthomonadaceae were more abundant in the cattle manure. Dissolved organic carbon (DOC) and TN emerged as the key determinants of bacterial community composition. Network analysis revealed that DOC had strong positive associations with some taxa (e.g. Comamonas , Leucobacter and Acidimicrobiales), whereas TN had negative associations with other taxa (e.g. Microbacteriaceae and Aeromicrobium). This study has revealed the key taxa related to the carbon and nitrogen cycle during composting with biochar. [ABSTRACT FROM AUTHOR]

• Diatomite and bentonite reduced the concentration of antibiotics and abundance of ARGs. • Diatomite and bentonite addition changed the composition of potential ARGs carrier. • Antibiotics and intI1 are vital drivers to influencing the abundance of ARGs. In this study, two typical minerals (diatomite and bentonite) were applied during composting, and their influences on antibiotics, antibiotic resistance genes (ARGs), intI1 and the bacterial communities were investigated. The relative abundance of total ARGs decreased by 53.72% and 59.54% in diatomite and bentonite addition compared with control on day 42. The minerals addition also reduced the relative abundance of intI1 , as much as 41.41% and 59.81% in diatomite and bentonite treatments. Proteobacteria and Firmicutes were the dominant candidate hosts of the major ARGs. There was a significant correlation between total ARGs and intI1 during the composting. Structural equation models further demonstrated that intI1 and antibiotics were the predominant direct factors responsible for ARG variations, and composting properties and bacterial community composition also shifted the variation of ARG profiles by influencing intI1. Overall, these findings suggest that diatomite and bentonite could decrease the potential proliferation of ARGs in chicken manure. [ABSTRACT FROM AUTHOR]

• Seaweed fertilizer enhanced urease and dehydrogenase activities during composting. • Seaweed fertilizer improved the microbial metabolic activity of compost. • The abundance of keystone species was increased by addition of seaweed fertilizer. • NO 3 −-N content exhibited a positive association with Aeromicrobium. The objective of this study was to investigate microbial responses when seaweed fertilizer was added to maize straw compost. The metabolic characteristics and bacterial communities were assessed using 16S rRNA sequencing and Biolog analysis. Results showed that the urease, dehydrogenase, and metabolic activities improved on day 21 after the addition of seaweed fertilizer. Firmicutes, Proteobacteria, and Actinobacteria were the dominant phyla in the compost. The relative abundances of Proteobacteria and Actinobacteria were increased by addition of seaweed fertilizer during the early composting stage. Temperature, NH 4 +-N, NO 3 −-N concentrations, and carbon source metabolism had close relationships with bacterial community variation during composting. A network analysis revealed that NO 3 −-N content had a positive association with Aeromicrobium , and seaweed fertilizer application improved the growth of keystone species related to N cycling. These results suggested that seaweed fertilizer influenced bacterial community succession through its effects on N concentrations during the composting process. [ABSTRACT FROM AUTHOR]

Highlights • Wheat and maize straw biochar addition improved the maturity and fertility of compost product. • Biochar addition influenced the structure and functions of microbial community during composting process. • Network analysis revealed the close associations between bacterial taxa and the properties of compost. Abstract The present study determined the dynamic changes of bacterial community structures and its metabolism functions in rice straw composting process with different types of biochar addition. Results showed that both wheat and maize straw biochar addition greatly increased the temperatures and germination index. Biochar addition influenced microbial community structure and metabolic characteristics of the compost. Firmicutes , Actinobacteria and Proteobacteria were the dominant phyla throughout the process, and both biochar addition significantly increased the relative abundance of Actinobacteria phylum, especially genus Saccharomonospora. The abundance of bacterial genes related to amino acid metabolism, carbohydrate metabolism and energy metabolism were also increased with biochar addition. Moreover, total nitrogen was strongly affected by biochar addition and had the greatest influence on the bacterial community structure. These results indicated that biochar addition improved the maturity and fertility of the compost product as well as significantly regulated the microbial community structure and functions during composting process. [ABSTRACT FROM AUTHOR]