Analysis of volatile metabolites emitted by various species to reveal their roles in chemical ecology and healthcare

Volatile organic compounds (VOCs) or volatile metabolites are small molecules and comprise a chemically diverse group of organic compounds, with a low molecular weight in the range of approximately 500 Daltons. They have low boiling points and high vapor pressure under ambient conditions. VOCs contribute only a small proportion of the metabolites produced by living organisms, however because of their important roles in chemical ecology and human healthcare, determining and analyzing the roles of these compounds is crucial for understanding of living systems. In the present study, we have developed a database of VOCs emitted by various living organisms and analyzed their roles in the aspect of chemical ecology and healthcare. Hierarchical and graph-clustering methods were used to cluster 517 microorganism species based on their emitting VOCs. From the clustering results, we found consistency between VOC and pathogenicity-based classification of microorganisms. In addition, we also performed the heatmap clustering and Multidimensional Scaling (MDS) based on Tanimoto coefficient as the similarity index of the chemical structure to cluster all 236 VOCs emitted by various biological species. Clustering results show that similar chemical structure may exhibit similar biological activity.