Empirical results of PCR using different nifH primer sets with DNA from isolates and soilsa.

aDNA samples and their phylogenetic affiliation in the nifH phylogeny from Figure S2 are: Desulfovibrio vulgaris Hildenborough (Dv), cluster III; Geobacter uraniireducens Rf4 (Gu), subcluster IA; Azotobacter vinelandii DJ (Av), Alpha-, Beta- and Gamma-Proteobacteria; Frankia sp. CcI3 (Fs), Frankia; Mastigocladus laminosus UTEX LB 1931 (Ml), Cyanobacteria; Klebsiella pneumoniae 342 (Kp), Alpha-, Beta- and Gammaproteobacteria; Xanthobacter autotrophicus Py2 (Xa), Alpha-, Beta- and Gammaproteobacteria; Rhodobacter sphaeroides 2.4.1 (Rs), Alpha-, Beta- and Gammaproteobacteria; Rhizobium leguminosarium bv. trifolii (Rl), Alpha-, Beta- and Gammaproteobacteria; Polaromonas naphthalenivorans CJ2 (Pn), Alpha-, Beta- and Gammaproteobacteria; Eschericia coli (Ec), genomic-DNA negative control; agricultural soil (AS); lawn soil (LS); No Template Control (NT). The symbols used are: product of the correct size (+), no product produced (−), non-specific amplification producing multiple bands or a single band of the wrong size (ns), a smeared band of indiscriminate size overlapping in size with the expected product (s). Blank cells indicate that the evaluation was not performed.bAnnealing Temperature (AT) used in PCR.