37 / 2021-06-29 08:59:51

Response of microbial communities to imbedded adsorbents during composting: Emphasis on the function roles of putative keystone taxa

Composting; Biochars; Cotton balls; Bacterial roles; Heavy metals speciation; Organic substances transformation

Intensive farming produces large amounts of manures. Heavy metals from livestock manures are the main factor limiting the resource utilization. Composting is the common way to treat livestock manures. Meanwhile, the bioavailability of heavy metals could be mitigated during composting. However, the passivation efficiency of heavy metals remained at a low level during composting, and the functional roles of microbial community is unclear. Therefore, imbedded adsorbents were applied to composting in this study. The aim was to explore effects of imbedded adsorbents and  response of microbial communities. Biochars, alkali modified biochars and pretreated cotton balls were employed as adsorbents with encapsulated and imbedded to composting. The results showed that imbedded adsorbents promoted organic matters degradation, the formation of humic acids and the transformation of heavy metals speciation during composting. Simultaneously, bacterial network and community structure were also influenced. Research suggested the transformation of organic substances and heavy metals speciation was not caused by variable community during composting with imbedded adsorbents, but by stable community. Ultimately, 30 genera of stable community were found, among which 6 genera were significantly correlated with environmental factors and played an important roles. Therefore, this study further revealed response of bacterial community and impacting mechanism of imbedded adsorbents, which provide theoretical support and technical guidance for the efficient utilization of livestock manures.