FIGURE 4.

Cysteine-degrading genes are actively expressed in healthy adults. This analysis confirms that the H₂S producing genes considered in this work are actively expressed in healthy adults. The y-axis displays TPM counts for each gene involved in H₂S production via both cysteine degradation and dissimilatory sulfate reduction. The legend on the right indicates the mode of H₂S production for each of the genes examined. Metatranscriptomic reads from HPFS (number of individuals = 308, number of samples = 677) (David et al., 2014; Abu-Ali et al., 2018) (number of individuals = 10, number of samples = 59) (David et al., 2014) were aligned to gene hit sequences identified in the homolog search step using salmon (Patro et al., 2017) and visualized by the ggplot2 (Wickham, 2011) package in R (Supplementary Figure 1C). Certain primary and secondary H₂S producing genes are actively produced by gut bacteria in healthy adults and erroneous producers of H₂S appear to be less actively transcribed.