FIGURE 5.

Expression of pmoA, pxmA, nirS, norB1, and norB2 in Methylomicrobium album strain BG8 cultivated in NMS or NMS media amended with 1 mM NaNO₂. Total RNA was extracted from Methylomicrobium album strain BG8 at 24, 48, and 72 h of growth (see Figure 1) from three separate cultures, converted to cDNA, and the abundance of pmoA, pxmA, nirS, norB1, and norB2 transcripts was determined using quantitative PCR. The transcript abundance of each gene of interest was normalized to that of 16s rRNA. The n-fold change in transcript abundance of the NO₂^- amended (1 mM NaNO₂) NMS cultures relative to the unamended NMS cultures at 24 h of growth (light gray), 48 h of growth (diagonal white/gray), and at 72 h of growth (black). Error bars represent the SD calculated for triplicate qPCR reactions performed on each of the three biological replicates for each treatment. The (^∗) above the bars designates a statistical significance (P < 0.05) as determined by t-test between NMS only and NMS + NO₂^- for each time point.