Patterns of the fly associated bacteria Ignatzschineria Tóth 2007 and Wohlfahrtiimonas Tóth 2008 (Gammaproteobacteria; Xanthomonadales; Xanthomonadaceae) on cadavers through time

The important role insects have during the decomposition process and in estimating the post-mortem interval in forensic investigations is well established. Among the first colonizers of a corpse, sometimes within minutes of death, flies may play an important role in the establishment of a cadaver-specific microbiome and affect the succession of a cadaver’s microbial community structure as decomposition progresses. To explore the skin microbiome of decomposing human cadavers, three cadaver pairs (six bodies total) were placed outdoors to decompose under natural conditions. A pair was placed during either winter, spring, or summer months at the Southeast Texas Applied Forensic Science (STAFS) facility (a willed body facility) at the Center for Biological Field Studies (CBSF), Sam Houston State University; Huntsville, Texas. Bacterial swabs of the mouth, right cheek, right bicep, medial torso region (above sternum), and of the feces were collected at various points during decomposition. Sample processing, amplification, and Illumina 16s rRNA sequencing were performed following protocols benchmarked as part of the Human Microbiome Project. 16s rRNA data were processed and analyzed using the open source software QIIME version 1.7.0. Results indicate that during the warmer months, Ignatzschineria and Wohlfahrtiimonas, genera traditionally associated with blow flies and flesh flies, dominate while during the cooler months, are present but at lower relative abundance. Additionally, Ignatzschineria and Wohlfahrtiimonas are prevalent during wet decomposition (active decay). Patterns of Ignatzschineria and Wohlfahrtiimonas relative abundance may be driven by fly activity, which is greatest during wet decomposition and influenced by seasons. These data may have significant influence on microbial successional models being developed to aid in the estimation of the post-mortem interval.