Table A2.

Primer sequences and PCR conditions of the three primer sets.

Primer Set	Target position	Sequence (5′-3′)	Ta‡ (°C)	Primer conc. (μM)	Mg2+ conc. (mM)
dxnA1/dfdA1	145-150*	TACAAVGGGCTGRTTTTCGG	51	1.2	4
	312-307*	GARAAVTTVGGGAACAC
dbfA1	205-210*	GGCGACGACTAYCACGTGCT	51	0.8	3.5
	373-368*	TCGAAGTTCTCGCCRTCRTC
carAa	69-74†	TGCCTNCAYCGHGGBGT	63	0.8	2.5
	268-263†	TTSAGHACRCCBGGSAGCCA

These PCR conditions were optimized for the soil samples described. The target positions described are for reference amino acid sequences:

^*position based on Sphingomonas wittichii RW1, dxnA1, and

^†position based on Sphingomonas sp. KA1, carAa.

^‡annealing temperature.