Recycling of Solid Organic Wastes Through Vermicomposting: Microbial Community Changes Throughout the Process and Use of Vermicompost as a Soil Amendment

Vermicomposting (i.e., the processing of organic waste by earthworms) is a low-cost rapid technique for transforming large amounts of waste into a safe and valuable product called vermicompost. The effects that earthworms have on microorganisms largely determine the rate of decomposition of organic matter during the process and, in turn, the quality of the final product. Recent studies highlight the importance of the earthworm gut as a major shaper of microbial communities. Passage of the material through the earthworm gut favors the existence of a reduced but more active microbial population in the egested material. The addition of these microbial communities to fresh organic matter has been shown to modify the level of activity and the functional diversity of microbial populations in vermicomposting systems. A review of the main changes observed in the structure and activity of microbial communities during vermicomposting is discussed, to provide further insight into the role of vermicompost as a soil amendment. The mechanisms involved and the factors that determine the suppression of pests are also addressed in this review article.