Soil metabarcoding identifies season indicators and differentiators of pig and Agrostis/Festuca spp. decomposition

To gain a better understanding of how environmental microbiota respond to cadaver decomposition, a forensic ecogenomic study was made with soil only control and 4 g each of Sus scrofa domesticus and plant litter (Agrostis/Festuca spp.) buried individually in a sandy clay loam (80 g) in sealed but perforated triplicate microcosms. The next-generation sequencing (Illumina Miseq) of the soil bacteria (16S rRNA gene) clade revealed seasonal taxomonic shifts at genus-level for the pig and plant litter microcosms compared to the non-burial controls. In particular, numerical abundances of Sphingobacterium (5.9%) and Pedobacter (24.1%) for the pig microcosms, and Rhodanobacter (18.1%) and Shinella (4.6%) for the plant litter microcosms, identified bacterial genera that could be tracked to establish a (seasonal) subsurface postmortem microbial clock. Also, family-level resolution revealed members that were unique to the control, grass and pig soils after 365 days.