Microbial succession in decomposing carrion is driven by time, modulated by insects and microbial perturbation

Recent research into decomposition has shed light on the intricate interplay within multi-kingdom communities, with microbial populations emerging as key players in the breakdown process and emphasizing their interactions within the broader decomposer ecosystem. Despite this, the specific roles and regulatory mechanisms of microbial communities remain underexplored. Gaining deeper insight into these dynamics is essential for advancing ecological and forensic sciences. This study examines the role of microbes in decomposition, particularly in relation to insect activity and external microbiome alterations. We used 12 piglet (Sus scrofa) cadavers placed in a rural area in southern Australia, to investigate how experimental insect exclusion and microbial perturbation affects decomposition. Bacterial microbial composition was quantified using 16S technology and compared among treatments and time points. Results showed significant shifts in bacterial diversity and abundance across time points sampled, with early-stage decomposition characterized by a higher abundance of Firmicutes and Actinobacteria, followed by a dominance of Proteobacteria in later stages. Principal coordinate analysis confirmed these patterns, showing that while decomposition stage is the primary driver of diversity, insect access and microbial perturbation shape microbial stability and community shifts rather than overall diversity. This challenges assumptions that external factors strongly influence diversity and highlights the need to consider both time and microbial dynamics in forensic applications, particularly for post-mortem interval estimation.