Bacterial Succession during Vermicomposting of Silver Wattle (Acacia dealbata Link)

Vermicomposting is the process of organic waste degradation through interactions between earthworms and microbes. A variety of organic wastes can be vermicomposted, producing a nutrient-rich final product that can be used as a soil biofertilizer. Giving the prolific invasive nature of the Australian silver wattle Acacia dealbata Link in Europe, it is important to find alternatives for its sustainable use. However, optimization of vermicomposting needs further comprehension of the fundamental microbial processes. Here, we characterized bacterial succession during the vermicomposting of silver wattle during 56 days using the earthworm species Eisenia andrei. We observed significant differences in alpha- and beta-diversity between fresh silver wattle (day 0) and days 14 and 28, while the bacterial community seemed more stable between days 28 and 56. Accordingly, during the first 28 days, a higher number of taxa experienced significant changes in relative abundance. A microbiome core composed of 10 amplicon sequence variants was identified during the vermicomposting of silver wattle (days 14 to 56). Finally, predicted functional profiles of genes involved in cellulose metabolism, nitrification, and salicylic acid also changed significantly during vermicomposting. This study, hence, provides detailed insights of the bacterial succession occurring during vermicomposting of the silver wattle and the characteristics of its final product as a sustainable plant biofertilizer.

Automated summary

Vermicomposting is a process that uses earthworms and microbes to degrade organic waste, producing a nutrient-rich soil biofertilizer. This study investigated the bacterial succession during the vermicomposting of the invasive plant species, silver wattle, utilizing the earthworm species Eisenia andrei. The researchers observed significant changes in bacterial diversity and community composition during the first 28 days of vermicomposting, while the community seemed more stable between days 28 and 56. The study also identified a core microbiome and found significant changes in predicted functional profiles of genes involved in cellulose metabolism, nitrification, and salicylic acid.