TABLE 1.

Primers used for PCR amplification of target groups in the A, B, unsaturated C (C-u), and saturated C (C-s) horizons

Target domain or metabolic group	Target gene	Primer	Sequence	Reference(s) for protocol	PCR amplificationa
					A	B	C-u	C-s
Bacteria	16S rRNA	27F	5′-AGAGTTTGATCCTGGCTCAG-3′	45	+	+	+	+
		1492R	5′-GGTTACCTTGTTACGACTT-3′
Archaea	16S rRNA	A21F	5′-TTCCGGTTGATCCYGCCGGA-3′	16	−	+	+	+
		A958R	5′-YCCGGCGTTGAMTCCAATT-3′
Denitrifying bacteria	nirK	583Fdg	5′-TCATGGTGCTGCCGCGYGANGG-3′	9, 70	−	−	−	−
		nirK5R	5′-GCCTCGATCAGRTTRTGG-3′
Denitrifying bacteria	nirS	nirS1F	5′-CCTAYTGGCCGCCRCART-3′	9	−	−	−	−
		nirS6R	5′-CGTTGAACTTRCCGGT-3′
Ammonia-oxidizing bacteria	amoA	AmoA-1F*	5′-GGGGHTTYTACTGGTGGT-3′	69, 78	−	−	−	−
	AmoA-2R	5′-CCCCTCKGSAAAGCCTTCTTC-3′
Ammonia-oxidizing archaea	amoA	Arch-amoAF	5′-STAATGGTCTGGCTTAGACG-3′	24	−	+	+	+
	Arch-amoAR	5′-GCGGCCATCCATCTGTATGT-3′
Sulfate-reducing bacteria	dsrAB	DSR1F	5′-ACSCACTGGAAGCACG-3′	88	−	−	−	+
	DSR4R	5′-GTGTAGCAGTTACCGCA-3′

^aSuccessful (+) or unsuccessful (−) PCR amplification for target groups within soil horizon aggregates.