Soil organic matter (SOM) determines essential soil properties like water and nutrient storage capacity and soil structure resistance to compaction and erosion. Nutrient availability for plants depends on SOM mineralization. Consequently, SOM conservation is an important part of sustainable ecosystem management. Soil microbes perform most of SOM mineralization in many ecosystems. However, their community structure and activity are largely regulated by soil fauna first during gut transit and afterwards in faecal pellets.

The millipede P. laminata is a soil ecosystem engineer and the most abundant macro-fauna species in Japanese larch plantation forests. Most of its impact on soil functioning is probably mediated by its faeces. The larvae are geophagous which is very rare in millipedes. Few studies have been conducted on macro-fauna faeces and the re-ingestion has never been taken into account. However, re-ingestion of faecal pellets is known to be very common in soil ecosystems.

P. laminata faeces were collected in laboratory conditions. Fresh faeces produced huge quantities of available N. The microbial community of the faeces was specific and altered by gazing from F. candida, which was assed by biochemical (PLFA) and molecular (T-RFLP) microbial fingerprinting methods. Thus, re-ingestion is important for SOM dynamics.