Temperature affects microbial decomposition of cadavers (Rattus rattus) in contrasting soils

“…Other research [43,69] have suggested below-ground decomposition rates follow a sigmoidal pattern rather than an above-ground linear one once local site temperatures are taken into account, but this research suggests a two-stage linear relationship between conductivity and ADD during the first two years of burial. The first 307 post-burial days also showed a high degree of correlation (Fig.…”

Section: Discussionmentioning

confidence: 97%

“…The target body will also be highly variable from case to case, including target size and organic content, depth of burial and time of deposition. Burial depth is important as this will affect temperature and the associated rate of decomposition [36,43]. The time of burial will be important, especially in seasonal climates, for example, if death occurs in the summer season the decomposition would occur more rapidly than if it occurred during the winter [45].…”

Section: Discussionmentioning

confidence: 99%

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Preliminary soilwater conductivity analysis to date clandestine burials of homicide victims

Pringle

Cassella

Jervis

2010

Forensic Science International

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This study reports on a new geoscientific method to estimate the post-burial interval (PBI) and potential post-mortem interval (PMI) date of homicide victims in clandestine graves by measuring decomposition fluid conductivities. Soil water analysis from a simulated clandestine grave (which contained a domestic pig carcass) in a semi-rural environment had significantly elevated conductivity measurements when compared to background values. A temporal rapid increase of the conductivity of burial fluids was observed until one year post burial, after this values slowly increased until two years (end of the study period). Conversion of x-axis from post-burial days to 'accumulated degree days' (ADD) resulted in an improved fit for multiple linear regression analyses. ADD correction allowed comparison with two other conductivity grave studies and demonstrated it was possible to date a discovered grave and hence the victim if past local temperatures could be obtained and burial depth measured. Contemporary soil moisture sampling was also undertaken to quantify this potential variable. Research also has implications to time illegal animal burials. Further research is required to extend the monitoring period, to use human cadavers and investigate other soil types and depositional environments. NOTICE: this is the author's version of a work that was accepted for publication in Forensic Science International. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Forensic Science International, v. 198, May 2010, doi:10.1016/j.forsciint.2010 Determining PMI of recently deceased individuals have been extensively researched using a variety of methods and revisions to said methods. However, dating PMI over a longer time period or importantly the Post-Burial Interval (PBI) emplacement within a burial site is more uncertain and lacking a simple technique.This manuscript is the first to document a new and simple technique to date PMI or estimate how long a body may have been buried for using the conductivity of the decomposition fluids. Our previous FSI paper ( Jervis et al. 2009) has suggested that these fluids are the primary reason why electrical resistivity surveys work to detect the positions of clandestine burials of homicide victims. Our new suggested PBI/PMI technique, based on a two year monitoring study, is to simply measure the conductivity of decomposing fluids as we have found this has a two-step, linear relationship. Results are reinforced by comparison to another study as well as to a simulated "discovered" burial, where a ~16% error was found between the conductivity estimated date compared to the true burial date. We have also converted post-burial days into accumulated degree days (ADD) which improved the date mis-match error (to ~12%) and will...

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“…However, recent research indicates that microbial communities change significantly, following a predictable timescale during decomposition [15]. The initial bacterial community varies with the age [16] and health [17] of the victim, the location on the body [18], environmental temperature and humidity [19], and the season [20][21]. Variation also exists within organs, for example, the species of bacteria in the right lobe of the liver (Escherichia coli) differ from those in the left lobe (Bacillus subtilis) [22].…”

Section: Introductionmentioning

confidence: 99%

Microbial effects on the development of forensically important blow fly species

Crooks

Bulling

Barnes

2016

Forensic Science International

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Colonisation times and development rates of specific blow fly species are used to estimate the minimum Post Mortem Interval (mPMI). The presence or absence of bacteria on a corpse can potentially affect the development and survival of blow fly larvae. Therefore an understanding of microbial-insect interactions is important for improving the interpretation of mPMI estimations. In this study, the effect of two bacteria (Escherichia coli and Staphylococcus aureus) on the growth rate and survival of three forensically important blow fly species (Lucilia sericata, Calliphora vicina and Calliphora vomitoria) was investigated.Sterile larvae were raised in a controlled environment (16:8h day: night light cycle, 23:21˚C day: night temperature cycle and a constant 35% relative humidity) on four artificial diets prepared with 100µl of 10 5 CFU bacterial solutions as follows: 1) E. coli 2) S. aureus 3) a 50:50 E. coli: S. aureus mix and 4) a sterile bacteria-free control diet. Daily measurements (length, width and weight) were taken from first instar larvae through to the emergence of adult flies. Survival rates were also determined at pupation and adult emergence. Results indicate that bacteria were not essential for the development of any of the blow fly species.However, larval growth rates were affected by bacterial diet, with effects differing between blow fly species. Peak larval weights also varied according to species-diet combination; C.vomitoria had the largest weight on E. coli and mixed diets, C. vicina had the largest weight on S. aureus diets, and treatment had no significant effect on the peak larval weight of L.sericata. These results indicate the potential for the bacteria that larvae are exposed to during development on a corpse to alter both developmental rates and larval weight in some blow fly species.

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Temperature affects microbial decomposition of cadavers (Rattus rattus) in contrasting soils

Cited by 145 publications

References 26 publications

Shifts in soil biodiversity—A forensic comparison between Sus scrofa domesticus and vegetation decomposition

Shifts in soil biodiversity—A forensic comparison between Sus scrofa domesticus and vegetation decomposition

Preliminary soilwater conductivity analysis to date clandestine burials of homicide victims

Microbial effects on the development of forensically important blow fly species

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