Table 1.

Selected primers used for amplification.

target gene	primer	nucleotide sequence (5′ → 3′)	reference
nirS	cd3aF	GTSAACGTSAAGGARACSGG	[31]
	R3cd	GASTTCGGRTGSGTCTTGA
nifH	F2	TGYGAYCCIAAIGCIGA	[32]
	R6	TCIGGIGARATGATGGC