Denitrification within the genus Azospirillum and other associative bacteria

Abstract

This paper originates from an address at the 8th International Symposium on Nitrogen Fixation with Non-Legumes, Sydney, NSW, December 2000 Different Azospirillumstrains and some other plant growth-promoting rhizobacteria (PGPR) were screened for the occurrence of genes coding for denitrification and nitrogenase reductase (nifH) using polymerase chain reaction (PCR)-based techniques. All PGPR examined were nitrogenase-positive. Azospirillum strains were remarkably dissimilar with respect to denitrification capabilities, in particular with respect to genes of the dissimilatory nitrite reductase. A. brasilense, A. lipoferum and A. halopraeferens strains possess a cytochrome cd1-containing nitrite reductase with low sequence similarities among them. A. irakense and A. doebereinerae have a Cu-containing nitrite reductase and A. amazonense is unable to denitrify. The molecular data were corroborated by activity measurements. The current results indicate that the inability to perform denitrification is unlikely a selective advantage for Azospirillum spp. and other associative bacteria for forming an association with plant roots.

Elevated Air Humidity Changes Soil Bacterial Community Structure in the Silver Birch Stand

“…The N 2 O reducer community structure was analyzed using nitrous oxide reductase-encoding nosZ genes from clades I and II (marked as nosZI% and nosZII% , respectively) and N 2 O reduction potential using the proportion of all nosZ genes ( nosZ% ) in bulk soil and rhizosphere bacterial community. The primer pairs were nirScd3a and nirSR3d (Kandeler et al, 2006) for nirS , FlaCu and R3Cu (Hallin and Lindgren, 1999) for nirK , nosZF8 (Kloos et al, 2001) and nosZ1622R (Throbäck et al, 2004) for nosZI , and nosZIIF and nosZIIR (Jones et al, 2013) for nosZII amplification. The details about the primers and optimized qPCR reaction conditions are given in Supplementary Table 2.…”

Exposure to vancomycin causes a shift in the microbial community structure without affecting nitrate reduction rates in river sediments

“…Primer annealing took place at 55°C, and PCR reaction was 30 cycles long. To characterize the N 2 O reducing bacteria, PCR amplification with MyTaq (BioLine, London, UK) of a 411-bp fragment of the nosZ gene was conducted using the nosZ-F (5′-CGYTGTTC MTGGACAGCCAG; (Kloos et al 2001) and nosZ1622Rb (5′-CGCRASGGCAASAAGGTSCG; (Throbäck et al 2004) primer set, with a 33-bp GC-clamp attached to the 5′ end of the latter primer. Primer annealing was conducted with a touchdown from 62 to 55°C during 35 cycles followed by 10 cycles at 55°C for sediment samples, and 45 cycles at 55°C for enrichment samples.…”

Potential of denitrification and nitrous oxide production from agricultural soil profiles (Seine Basin, France)

“…In order to study the N 2 O reducing bacteria, PCR amplification of a 411-bp fragment of the nosZ gene was conducted using the nosZ-F (5 0 -CGYTGTTCM TGGACAGCCAG; Kloos et al 2001) and nosZ16 22Rb (5 0 -CGCRASGGCAASAAGGTSCG; Throbäck et al 2004) primer set, with a 33-bp GC-clamp attached to the 5 0 end of the latter primer. The reaction mixtures comprised 5 lLof 59 reaction buffer, 1.5 mM MgCl 2 , 300 lM of each dNTP, 25 pmol of each primer, and 0.5 lL of Phire Ò Hot Start II DNA Polymerase (Finnzymes, Espoo, Finland).…”