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 pro duction 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.
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The smell of death. State-of-the-art and future research directions
The decomposition of a body is inseparably associated with the release of several types of odors. This phenomenon has been used in the training of sniffer dogs for decades. The odor profile associated with decomposition consists of a range of volatile organic compounds (VOCs), chemical composition of which varies over time, temperature, environmental conditions, and the type of microorganisms, and insects colonizing the carcass. Mercaptans are responsible for the bad smell associated with corpses; however, there are no unified recommendations for conducting forensic analysis based on the detectable odor of revealed corpses and previous research on VOCs shows differing results. The aim of this review is to systematize the current knowledge on the type of volatile organic compounds related to the decomposition process, depending on a few variables. This knowledge will improve the methods of VOCs detection and analysis to be used in modern forensic diagnostics and improve the methods of training dogs for forensic applications.
more » « less- Award ID(s):
- 2011764
- PAR ID:
- 10503947
- Publisher / Repository:
- Frontiers in Microbiology
- Date Published:
- Journal Name:
- Frontiers in Microbiology
- Volume:
- 14
- ISSN:
- 1664-302X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Biogenic volatile organic compounds (VOCs) constitute a significant portion of gas-phase metabolites in modern ecosystems and have unique roles in moderating atmospheric oxidative capacity, solar radiation balance, and aerosol formation. It has been theorized that VOCs may account for observed geological and evolutionary phenomena during the Archaean, but the direct contribution of biology to early non-methane VOC cycling remains unexplored. Here, we provide an assessment of all potential VOCs metabolized by the last universal common ancestor (LUCA). We identify enzyme functions linked to LUCA orthologous protein groups across eight literature sources and estimate the volatility of all associated substrates to identify ancient volatile metabolites. We hone in on volatile metabolites with confirmed modern emissions that exist in conserved metabolic pathways and produce a curated list of the most likely LUCA VOCs. We introduce volatile organic metabolites associated with early life and discuss their potential influence on early carbon cycling and atmospheric chemistry.
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Abstract Volatile organic compounds (
VOC s) are by‐products of cadaveric decomposition and are responsible for the odor associated with decomposing remains. The direct link betweenVOC production and individual postmortem microbes has not been well characterized experimentally. The purpose of this study was to profileVOC s released from three postmortem bacterial isolates (Bacillus subtilis, Ignatzschineria indica, I. ureiclastica) using solid‐phase microextraction arrow (SPME Arrow) and gas chromatography–mass spectrometry (GC ‐MS ). Species were inoculated in headspace vials on Standard Nutrient Agar and monitored over 5 days at 24°C. Each species exhibited a differentVOC profile that included common decompositionVOC s.VOC s exhibited upward or downward temporal trends over time.Ignatzschineria indica produced a large amount of dimethyldisulfide. Other compounds of interest included alcohols, aldehydes, aromatics, and ketones. This provides foundational data to link decomposition odor with specific postmortem microbes to improve understanding of underlying mechanisms for decompositionVOC production. -
null (Ed.)Soils harbor complex biological processes intertwined with metabolic inputs from microbes and plants. Measuring the soil metabolome can reveal active metabolic pathways, providing insight into the presence of specific organisms and ecological interactions. A subset of the metabolome is volatile; however, current soil studies rarely consider volatile organic compounds (VOCs), contributing to biases in sample processing and metabolomic analytical techniques. Therefore, we hypothesize that overall, the volatility of detected compounds measured using current metabolomic analytical techniques will be lower than undetected compounds, a reflection of missed VOCs. To illustrate this, we examined a peatland metabolomic dataset collected using three common metabolomic analytical techniques: nuclear magnetic resonance (NMR), gas chromatography-mass spectroscopy (GC-MS), and fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). We mapped the compounds to three metabolic pathways (monoterpenoid biosynthesis, diterpenoid biosynthesis, and polycyclic aromatic hydrocarbon degradation), chosen for their activity in peatland ecosystems and involvement of VOCs. We estimated the volatility of the compounds by calculating relative volatility indices (RVIs), and as hypothesized, the average RVI of undetected compounds within each of our focal pathways was higher than detected compounds ( p < 0.001). Moreover, higher RVI compounds were absent even in sub-pathways where lower RVI compounds were observed. Our findings suggest that typical soil metabolomic analytical techniques may overlook VOCs and leave missing links in metabolic pathways. To more completely represent the volatile fraction of the soil metabolome, we suggest that environmental scientists take into consideration these biases when designing and interpreting their data and/or add direct online measurement methods that capture the integral role of VOCs in soil systems.more » « less
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Science for Society Buildings account for a significant fraction of the land area in cities and actively exchange air with their proximate outdoor environments via mechanical ventilation systems. However, the direct impact of buildings on urban air pollution remains poorly characterized. Due to reductions in traffic-associated emissions of volatile organic compounds (VOCs), volatile chemical products, which are widely used inside buildings, have become a major VOC source in urban areas. Indoor-generated VOCs are likely to be an important contributor to the VOC burden of the urban atmosphere, and ventilation systems provide a pathway for VOCs to be released outdoors. Here, we show how modern buildings act as significant emission sources of VOCs for the outdoor environment. Our results demonstrate that future air quality monitoring efforts in cities need to account for direct VOC discharge from buildings in order to capture emerging sources of environmental pollution that can impact the climate and human health. Summary Urban air undergoes transformations as it is actively circulated throughout buildings via ventilation systems. However, the influence of air exchange between outdoor and indoor atmospheres on urban air pollution is not well understood. Here, we quantify how buildings behave as a dynamic source and sink for urban air pollutants via high-resolution online mass spectrometry measurements. During our field campaign in a high-performance office building, we observed that the building continually released volatile organic compounds (VOCs) into the urban air and removed outdoor ozone and fine particulate matter. VOC emissions from people, their activities, and surface reservoirs result in significant VOC discharge from the building to the outdoors. Per unit area, building emissions of VOCs are comparable to traffic, industrial, and biogenic emissions. The building source-sink behavior changed dynamically with occupancy and ventilation conditions. Our results demonstrate that buildings can directly influence urban air quality due to substantial outdoor-indoor air exchange.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3389/fmicb.2023.1260869
