Table 1. Candidate reference genes evaluated in this study.

Approach	Gene	Description	Reference
Bibliographic search	rrn16S	16S ribosomal RNA	[20], [31]–[37]
	petB	Cytochrome b 6, involved in electron transport and ATP generation	[38]
	ppc	Phosphoenolpyruvate carboxylase (PEPC), central enzyme in carbon concentrating mechanism	[39]
	rnpA	Protein subunit of ribonuclease P (RNase P)	[38]
	rnpB	RNA subunit of ribonuclease P	[40]–[44]
	rps1B	Small subunit ribosomal protein S1	[42], [44]
	rpoA	RNA polymerase, alpha subunit	[45]–[46]
CyanoBIKE *	ilvD	Dihydroxyacid dehydratase, participates in the biosynthetic process of branched chain amino acid family	This study
	mrp	Multiple drug resistance protein (MRP) homolog	This study
	prsA	Ribose-phosphate pyrophosphokinase, involved in the pentose phosphate pathway	This study
	purC	SAICAR synthetase, involved in the de novo purine biosynthetic pathway	This study
	secA	Part of the Sec protein translocase complex	This study

^*Search based on the works by Ehira and Ohmori [20] and Hihara et al. [21].