Table 1.

Expression stability ranking of candidate reference genes.

Gene	geNorm	NormFinder
map	0.258 (1)*	0.311 (6)
rpoC	0.258 (1)*	0.290 (3)
era	0.416 (2)	0.201 (1)*
gmk	0.477 (3)	0.299 (4)
trpS	0.542 (4)	0.306 (5)
nth	0.581 (5)	0.265 (2)
rplI	0.616 (6)	0.425 (8)
gyrA	0.664 (7)	0.412 (7)
coaE	0.763 (8)	0.628 (9)

Ranking of the nine evaluated reference genes according to their expression stability under five different experimental conditions (♣) using geNorm [11] and NormFinder [7] applications.

* Genes with the most stable expression values.

() The rank of the genes is indicated in parentheses.

(♣) Experimental conditions. Condition 1: cells grown in 9 K medium at pH 1.6 containing 200 mM FeSO₄; condition 2: cells grown in 9 K medium at pH 2.5 containing 1% elemental sulfur; condition 3: cells grown in 9 K medium at pH 3.5 containing 1% elemental sulfur; condition 4: cells grown in 9 K medium at pH 4.5 containing 1% elemental sulfur; condition 5: cells grown in DSMZ71 medium at pH 4.5 containing 0.5% thiosulfate.