Authors:

Sarah Hong

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About Paper:

Hydrogen sulfide (H2S) is a genotoxin produced by sulfidogenic bacteria, and triggers hyperproliferative and proinflammatory pathways. This bacterial derived gas may be a mechanism of colorectal cancer (CRC), which is the second leading cause of cancer death world-wide. Furthermore, an abundance of sulfidogenic bacteria in the colonic mucosa are associated with CRC incidence rates in Black Americans. The intake of dietary fat and cysteine are positively associated with genes for sulfur metabolism. Dietary cysteine is prevalent in Black Americans as they consume more animal fat and red meat. Therefore, it is crucial to identify the link between H2S composition and risk of CRC by discovering if dietary cysteine intake is utilized by cysteine-metabolizing bacteria for the promotion of colonic inflammation and tumor formation. Thus, fecal H2S concentrations are examined by utilizing a colorimetric assay that turns black in the presence of H2S. Colonic microbes were separated from one gram of stool and inoculated into Sulfur, Indole, Motility (SIM) Medium. The formation of a black precipitate was detected with measurements of the optical density (OD) every hour thereby determining H2S production and growth potential. The fecal sample turned black. Additionally, the increase of OD is likely due to the black color formation. Overall, the assay has been successfully validated by using both human stool and a bacterium that is known to create H2S. These outcomes lay the groundwork for future studies to establish causality. This may lead to pharmaceutical and dietary interventions aimed at reducing H2S producing bacteria to prevent CRC. Keywords: Hydrogen Sulfide; Colorectal Cancer; Sulfidogenic Bacteria, Sulfide/Sulfite; Cysteine; Colonic Microbiome

Source:

Purdue University / 2024

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Co-authors:

Sarah Hong