The impact of carrion decomposition on the fatty acid methyl ester (FAME) profiles of soil microbial communities in southern Canada

Profiling microbial communities associated with cadaver decomposition may provide useful information concerning postmortem intervals and aid in the identification of clandestine graves. Four experiments using pig carcasses as human decomposition analogues were performed over the course of 2011 and 2012 in southern Ontario to document changes in soil microbiology following decomposition. Studies were conducted in both spring and summer to determine the effect of environmental variables on the decomposition process and subsequent changes in gravesoil microbiology. Fatty acid methyl ester (FAME) profiling was used to investigate the community level changes in soil throughout the decomposition process. Shifts in FAME profiles coincided with the onset of active decay and persisted through to the dry remains stage. Results also indicated that FAME profiles differed between seasons and years. These studies highlight the need to document natural changes in microbial communities over seasons and years to establish normal soil profiles and patterns to effectively use this analysis as a tool for post-mortem interval estimation or for locating clandestine graves.