Global biogeographic patterns and assembly processes of landfill leachate microbiomes

Approximately 95 % of municipal solid waste is disposed of in landfill globally, generating leachate that is known as a complex mixture of biodegradable and persistent toxic compounds. Microbes are main forces for tackling the toxic leachate but the patterns of microbial assembly in such treatments are largely unknown, limiting the proper optimization of leachate treatment efficiency. This study, for the first time, presents a global-scale analysis involving 151 landfill leachate treatment samples for uncovering mechanisms of microbial assembly from an ecological perspective. The information of microbiome from 97 treatments in Asia, 41 treatments in Europe, and 13 treatments in North America were collected. The results revealed pronounced biogeographic divergence, with Asian samples (particularly those from India) exhibiting lower microbial diversity and richness compared to Europe and North America counterparts. Geographical-climatic and socio-economic factors significantly influenced microbial composition, with elevation and per capita GDP being primary drivers. Further, the community assembly was predominantly governed by deterministic processes. Co-occurrence network analyses demonstrated distinct microbial interaction patterns across continents, with Asian networks being more vulnerable to collapse under external disturbances. This study provides critical insights into the global microbial ecology of landfill leachate treatment, offering a foundation for developing targeted bioremediation strategies.