Genes differentially expressed with nitrate versus fumarate. (A) Growth of G. lovleyi SZ with 20 mM acetate and 5 M nitrate or 20 mM fumarate as electron acceptor. Arrows show the point (OD₆₀₀, ca. 0.18) of cell harvesting for RNA extraction and mRNA sequencing (RNA-Seq). (B-C) Heatmap (B) and dispersion plot (C) of genes differentially upregulated or downregulated in triplicate cultures with nitrate (N) versus fumarate (F). The dispersion plot shows the log of transcript counts per million (CPM, >5) versus the log of fold change (FC, <−1 or > 1) for differentially expressed genes with a false discovery rate FDR < 0.05. The plot highlights upregulated genes encoding nitrate (nar and nap) or nitrite (nrf) reductases.