Molecular detection of nifH gene-containing Paenibacillus in the rhizosphere of sorghum (Sorghum bicolor) sown in Cerrado soil.
OBJECTIVE
To develop a polymerase chain reaction (PCR)-based approach for the detection of nifH gene-containing Paenibacillus in environmental samples.


RESULTS
The primers, nifHPAENf and nifHPAENr, were designed and tested with DNA from: (i) strains of different nitrogen-fixing Paenibacillus species, (ii) strains of other nitrogen-fixing genera and (iii) rhizosphere of sorghum sown in Cerrado soil amended with either 12 or 120 kg ha(-1) of nitrogen fertilizer. All nitrogen-fixing Paenibacillus strains tested and the DNA samples from rhizosphere soil were amplified when these primers were used, generating a 280 bp fragment. When the PCR products obtained from both sorghum rhizospheres were cloned and sequenced, the majority of the clones analysed could be identified as Paenibacillus durus. Moreover, a greater diversity in the nifH sequences could be observed in the rhizosphere treated with a high amount of nitrogen fertilizer.


CONCLUSIONS
Nitrogen fertilization slightly influenced the structure of the nifH gene-containing Paenibacillus community in sorghum rhizospheres cultivated in Cerrado soil.


CONCLUSIONS
The PCR detection method developed is adequate to assess the presence of nifH gene-containing Paenibacillus in the environment and can be used in future to determine the ecological role of this group of micro-organisms for the nitrogen input to the plants.
Coelho
M R R
MR
Universidade Federal do Rio de Janeiro, Instituto de Microbiologia Prof. Paulo de Góes, Rio de Janeiro, RJ, Brazil.
Carneiro
N P
NP
Marriel
I E
IE
Seldin
L
L
D001419:Bacteria / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification*; D001426:Bacterial Proteins / Q000235:genetics*; D044822:Biodiversity; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000235:genetics*; D018517:Plant Roots / Q000382:microbiology*; D012988:Soil Microbiology; D045868:Sorghum / Q000382:microbiology*
D001426:Bacterial Proteins; D010088:Oxidoreductases; C029130:nitrogenase reductase