Bergmann R C, Ralebitso-Senior T K, Thompson T J U
School of Science and Engineering, Teesside University, Borough Road, Middlesbrough, Teesside, TS1 3BA, United Kingdom.
Forensic Sci Int. 2014 Aug;241:190-4. doi: 10.1016/j.forsciint.2014.06.001. Epub 2014 Jun 11.
Despite emergent research initiatives, significant knowledge gaps remain of soil microbiology-associated cadaver decomposition. Nevertheless, preliminary studies have shown that the vast diversity and complex interactions of soil microbial communities have great potential for forensic applications such as clandestine grave location and postmortem interval estimation. This study investigated changes in soil bacterial communities during pig (Sus scrofa domesticus) leg decomposition. 16S rRNA, instead of the usually applied 16S rDNA marker, was used to compare the metabolically active bacteria. Total bacterial RNA was extracted from soil samples of three different layers on day 3, 28 and 77 after the shallow burial of a pig leg. The V3 region of the 16S rRNA was amplified, analysed by RT-PCR DGGE, and compared with control soil bacterial community profiles. Statistically significant differences in soil bacterial biodiversity were observed. For the control, bacterial diversity (H') and species richness (S) of the three layers averaged 2.48±0.14 (H') and 18.8±2.5 (S), respectively, while for the test soil increases (p=0.027) were recorded between day 3 (H'=2.71±0.02; S=21.3±2.0) and 28 (H'=3.46±0.32; S=60.3±16.9), particularly in the middle (10-20 cm) and bottom (20-30 cm) soil layers. Between day 28 and 77 the diversity and richness then decreased on average for all three layers (H'=3.43±0.20; S=60.0±17.3) but remained higher than on day 3. Thus, responses in soil bacterial profiles and activity to carcass decomposition, detected and characterised by RNA-based DGGE, could be used together with RNA sequencing data, changes in physico-chemical variables (carbon, nitrogen, phosphorus, temperature, redox potential, water activity and pH) and conventional macroecology markers (e.g. insects and vegetation), to develop a suite of analytical protocols for different forensic scenarios.
尽管有新的研究项目，但与土壤微生物相关的尸体分解仍存在重大知识空白。然而，初步研究表明，土壤微生物群落的巨大多样性和复杂相互作用在诸如秘密坟墓定位和死后间隔时间估计等法医应用方面具有巨大潜力。本研究调查了猪（家猪）腿部分解过程中土壤细菌群落的变化。使用16S rRNA而非通常应用的16S rDNA标记来比较代谢活跃的细菌。在猪腿浅埋后第3天、28天和77天，从三个不同土层的土壤样本中提取总细菌RNA。对16S rRNA的V3区域进行扩增，通过RT-PCR DGGE分析，并与对照土壤细菌群落图谱进行比较。观察到土壤细菌生物多样性存在统计学上的显著差异。对于对照，三层的细菌多样性（H'）和物种丰富度（S）平均分别为2.48±0.14（H'）和18.8±2.5（S），而对于测试土壤，在第3天（H'=2.71±0.02；S=21.3±2.0）和28天（H'=3.46±0.32；S=60.3±16.9）之间记录到增加（p = 0.027），特别是在中层（10 - 20厘米）和底层（20 - 30厘米）土壤层。在第28天和77天之间，所有三层的多样性和丰富度平均随后下降（H'=3.43±0.20；S=60.0±17.3），但仍高于第3天。因此，通过基于RNA的DGGE检测和表征的土壤细菌图谱和活性对尸体分解的响应，可与RNA测序数据、物理化学变量（碳、氮、磷、温度、氧化还原电位、水分活度和pH）的变化以及传统宏观生态学标记（如昆虫和植被）一起使用，以开发一套适用于不同法医场景的分析方案。
