MICROBIAL COMMUNITY SUCCESSION DURING DECOMPOSITION AND POTENTIAL FORENSIC APPLICATIONS

Abstract

Reliable estimation of post-mortem interval can be crucial in criminal investigations and required distinguishing different stages of decomposition. Microbial communities play a vital function in decomposition processes and can act as biomarkers to show predictable patterns of succession throughout the period of decomposition. Microbial biomarkers therefore have potential in estimating post-mortem interval (PMI) and developing an additional, reliable approach for determining PMI via microbial community succession. This study investigates the spatial and temporal dynamics of microbial taxa during swine carcass decomposition, examining microbial succession as potential biomarkers for post-mortem interval (PMI) estimation. Swine carcasses, which were used as proxies for this research, gave a comprehensive exploration of microbial communities across various ecological niches, with samples collected from body sites (mouth, belly, anus), internal organs (liver, lung), and surrounding environments (soil, seawater, freshwater, brackish water). Genomic DNA was extracted, quantified, and followed by a 16S rRNA gene amplification using next-generation sequencing (Illumina MiSeq). The bacterial composition and biodiversity were analysed using the EzbioCloud microbiome profiling tool, with statistical analyses revealing the microbial dynamics throughout decomposition. The result of this research advances the current understanding of microbial succession patterns in decomposition ecology, highlighting the challenging yet promising nature of identifying suitable microbial biomarkers for PMI estimation. No significant differences in overall community composition were revealed over time, however significant differences in specific bacterial taxa that can be used as post-mortem biomarkers were identified among body sites [belly: Bacteroidetes and families from Firmicutes (Clostridiaceae, Tissierellaceae), Actinobacteria (Corynebacteriaceae)], internal organs [liver: Firmicutes (Lactobacillaceae), and lung: Actinobacteria and Bacteroidetes], and environmental niches [Aquatic samples: Pseudomonadaceae (Proteobacteria), Bacteroidaceae (Bacteroidetes) and Acidaminococcaceae (Firmicutes), and soil: Chthoniobacteraceae (Verrucomicrobia) and Chitinophagaceae (Bacteriodetes)] as decomposition progresses. The identification of these specific bacterial taxa during different stages of decomposition offers further approach for estimating PMI, presenting microbial succession as a potential forensic tool.