Effect of Ignatzshineria indica (Gammaproteobacteria: Xanthomonadales) on rate of decomposition in mice

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Microbes have a major role from the onset of and throughout decomposition. Studies show that a decomposing body supports a necrobiome (Pechal et al., 2013), a term coined to mean a community of living things associated with decomposition of remains, specifically with reference to microorganisms. The objective of the current study is to show how Ignatzschineria indica, a fly associated, and selected bacteria associated with a decomposing human body affect decomposition under controlled (laboratory) conditions. The work presented here is a laboratory experiment carried out at Sam Houston State University, Huntsville, Texas. To assess the effect of Ignatzschineria indica bacteria on decomposition, 3 batches of 90 mice were subjected to 9 different bacterial treatments involving 4 bacteria; A [Ignatzschineria indica], B [Escherichia coli], C [Bacillus licheniformis], D [Salmonella enterica], and combinations of Ignatzchineria indica and other bacteria in the following manner BA, CA, DA, PC [positive control] and NC [negative control]. 270 mice were observed throughout their decomposition process. Results from this experiment showed that the initial bacteria composition in dead mice does not affect the rate of decomposition under laboratory controlled conditions of temperature and moisture, with the exclusion of vertebrate and invertebrate scavengers. Adding Ignatzchineria indica to dead mice specimens under laboratory controlled conditions does not significantly affect the rate of decomposition but instead affects the pathway of decomposition. This was evident from the different intensities of volatile organic compounds (VOCs) that were collected and assayed from the different samples. The same experiment shows that at any given time the ambient temperature is significantly different from the subjects’ temperatures during decomposition. Our findings lead us to conclude that the addition of Ignatzschineria indica bacteria to decomposing mice does not significantly alter the rate of decomposition. It does alter the chemical pathways of decomposition as evidenced by variant VOCs composition.

Decomposition, Ignatzchineria indica, Competitive exclusion, Accumulated Degree Days, Postmortem Interval