TABLE 1.

Bacterial strains and specificity of the PCR based on the nifH gene of P. azotofixans

Species	Strain	PCR producta	Origin or referenceb
P. azotofixans	ATCC 35681	+	32
	F102	+	32
	2RC1	+	32
	SD20	+	32
	C3L4	+	32
	RCPG7	+	32
	P3E20	+	32
	RBN4	+	32
	BE1	+	32
	SD17	+
P. durum	DSMZ 1735	+	DSMZ
P. polymyxa	DSMZ 356	−	DSMZ
	LMAU B58	−	Akkermans
	Loutit	−	CIM
P. macerans	LMD 24.3	−	CIM
	LMAU B57	−	DSMZ
Frankia sp.	Br	−	Ramirez
	AgKg4	−	Ramirez
	Hrl1	−	Ramirez
	Arl3	−	Ramirez
Azospirillum brasilense	LMAU A150	−	Akkermans
Azospirillum lipoferum	LMAU A146	−	Akkermans
Azotobacter beijerinckii	LMAU A34	−	Akkermans
Azotobacter chroococcum	LMAU A95	−	Akkermans
Azotobacter vinelandii	LMAU A66	−	Akkermans
Beijerinckia sp.	LMAU B50	−	Akkermans
Bradyrhizobium japonicum	LMAU R87	−	Akkermans
Rhizobium meliloti	LMAU R13	−	Akkermans
Rhizobium phaseoli	LMAU R19	−	Akkermans

^aThe PCR was performed with primers NHA1 and NHA2 specific to the nifH gene of P. azotofixans. +, present; −, absent. 

^bDSMZ, Deutsche Sammlung von Mikroorganismen und Zellkulturen, Braunschweig, Germany; Akkermans, A. D. L. Akkermans, Microbiology Department, Wageningen Agricultural University, Wageningen, The Netherlands; CIM, Collection of Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Ramirez, H. Ramirez, Microbiology Department, Wageningen Agricultural University, Wageningen, The Netherlands.