Laboratory of Forensic and Bioanalytical Chemistry, School of Natural Sciences and Mathematics, Chaminade University of Honolulu, United States.
School of Natural Sciences and Mathematics, Chaminade University of Honolulu, United States.
J Chromatogr A. 2024 Aug 2;1728:465017. doi: 10.1016/j.chroma.2024.465017. Epub 2024 May 22.
Decomposition odor is produced during postmortem mammalian tissue breakdown by bacteria, insects, and intrinsic chemical processes. Past research has not thoroughly investigated which volatile organic compounds (VOCs) can be linked directly to individual bacterial species on decomposing remains. The purpose of this study was to profile the VOCs produced over time by individual species of bacteria using comprehensive two-dimensional gas chromatography (GC×GC) to expand our foundational knowledge of what each bacterial species contributes to decomposition odor. Five different species of bacteria (Bacillus subtilis, Ignatzschineria indica, Ignatzschineria ureiclastica, Curtobacterium luteum, and Vagococcus lutrae) were cultured on standard nutrient agar individually and monitored daily using solid phase microextraction arrow (SPME Arrow) and GC×GC in combination with quadrupole mass spectrometry (qMS) and flame ionization detection (FID). The GC×GC-qMS/FID approach was used to generate rich VOC profiles that represented the bacterial species' metabolic VOC production longitudinally. The data obtained from the chromatographic output was used to compare with a prior study using one-dimensional GC-qMS, and also between each of the five species to investigate the extent of overlap between species. No single VOC could be found in all five bacterial species investigated, and there was little overlap in the profile between species. To further visualize these differences, chromatographic peak data was investigated using two different ordination strategies, principal component analysis (PCA) and principal coordinate analysis (PCoA). The two ordination strategies were compared with each other using a Procrustes analysis. This was performed to understand differences in ordination strategies between the separation science community and chemical ecological community. Overall, ordination strategies were found to produce similar results, as evidenced by the correlation of PCA and PCoA in the Procrustes analysis. All analysis strategies yielded distinct VOC profiles for each species. Further study of additional species will support understanding of the holistic view of decomposition odor from a chemical ecology perspective, and further support our understanding of the production of decomposition odor that culminates from such a complex environment.
死后哺乳动物组织在细菌、昆虫和内在化学过程的作用下会分解，产生分解气味。过去的研究尚未彻底调查哪些挥发性有机化合物（VOC）可以直接与分解遗骸中的单个细菌种类相关联。本研究的目的是使用全面二维气相色谱法（GC×GC）来分析随着时间的推移，每种细菌产生的 VOC，以扩展我们对每个细菌种类对分解气味贡献的基础知识。将五种不同的细菌（枯草芽孢杆菌、印度 Ignatzschineria、尿素 Ignatzschineria、黄杆菌和海獭 Vagococcus）分别在标准营养琼脂上培养，并使用固相微萃取（SPME）箭头和 GC×GC 结合四极杆质谱（qMS）和火焰电离检测（FID）进行每日监测。使用 GC×GC-qMS/FID 方法生成了丰富的 VOC 图谱，这些图谱代表了细菌物种的代谢 VOC 生产情况。从色谱输出中获得的数据用于与之前使用一维 GC-qMS 进行的研究进行比较，也用于五种细菌之间的比较，以调查物种之间的重叠程度。在所研究的五种细菌中，没有一种 VOC 可以在所有细菌中找到，而且物种之间的图谱重叠很少。为了进一步可视化这些差异，使用两种不同的排序策略（主成分分析（PCA）和主坐标分析（PCoA））对色谱峰数据进行了研究。使用 Procrustes 分析比较了两种排序策略。这是为了了解分离科学界和化学生态学界之间排序策略的差异。总体而言，排序策略产生了相似的结果，这一点可以从 Procrustes 分析中 PCA 和 PCoA 的相关性中得到证明。所有分析策略都为每个物种产生了独特的 VOC 图谱。对其他物种的进一步研究将支持从化学生态学角度理解分解气味的整体观点，并进一步支持我们对这种复杂环境下分解气味产生的理解。
