FIGURE 7.

Elevated hydrogenase levels in Cff-pgl mutants correlate with increased H₂ uptake. (A) Gene arrangements of hyn and hyp clusters in Cff ATCC 27374 with LFQ proteomic protein abundance in pgl mutants vs WT are shown. Protein fold changes of pglJ- and pglX- with respect to WT are indicated above and below each gene respectively. Genes with no values associated had no coverage in our proteomics data analyses. Only HynABC showed significant protein level increases when compared to WT. (B) Effect of H₂ on microaerobic growth of Cff WT, pglJ-, and pglX- strains. The data set is derived from three biological replicates (with two technical replicates each) of cells grown under the indicated condition. Number of cells obtained after 48 h of growth is represented by Log₁₀ colony forming units per mL (CFU/mL). The error bars represent the standard error within each group. (C,D) Whole cell H₂-uptake of Cff WT, pglX-, and pglJ- strains. Cff was grown on BHI agar in microaerophilic conditions for 24 h at 37°C in 10% H₂ (+H₂) or absence of hydrogen (–H₂). Whole cell H₂-uptake activity is expressed as nanomoles of H₂ used per min per 10⁹ cells. Results in (C) represent the mean ± SD of four independent assays; results in (D) represent the mean ± SD of two independent assays. p-values as analyzed by a two-tailed t-test are either indicated by an asterisk (*p-value ≤ 0.05 in B) or are directly included in the figure (for C,D).