Ecological role of earthworm intestinal bacteria in terrestrial environments: A review

Increasing evidence demonstrated the critical role the earthworm gut played in sustaining earthworm's metabolism and transformation of nutrients and pollutants in the environment. Being rich in nutrients, the earthworm gut is favorable for the colonization of (facultative) anaerobic bacteria, which bridge the host earthworm gut with adjacent terrestrial environment. Therefore, the status quo of earthworm gut research was primarily reviewed in this work. It was found that most studies focused on the bacterial composition and diversity of the earthworm gut, and their potential application in nutrient element and pollutant transformation, such as nitrification, methanogens, heavy metal detoxification, etc. Yet limited information was available about the specific mechanism of intestinal bacteria in nutrient and pollutant transformation. Therefore, in this work we highlighted the current problems and concluded the future prospect of worm's intestinal bacteria research. On one hand, high throughput sequencing and bioinformatics tools are critical to break the bottleneck in the intestinal bacteria research via clarifying the molecular mechanism involved in the transformation processes described above. In addition, a global dataset concerning worm gut bacteria will be needed to provide comprehensive information about intestinal bacteria pool, and act as a communication platform to further encourage the progress of worm gut research.