RESUMO
Gibberellins A(1), A(3), and iso-A(3) were identified from aseptic cultures of Azospirillum lipoferum strain op 33 by capillary gas chromatography-mass spectrometry (GC-MS) and GC-MS-selected ion monitoring. There were 20 to 40 picograms (in GA(3) equivalents, estimated from bioassay) of gibberellins A(1) and A(3) per milliliter of cell culture (containing 10(9) cells).
RESUMO
Thirty indigenous rhizobia strains, isolated from Lotus tenuis in the area of Chascomús and other regions of the Salado River Basin (Argentina), were characterized based on generation time, acid production, carbon utilization, protein profile, and molecular characterization by restriction fragment length polymorphism (RFLP) analysis of 16S rRNA genes amplified by the polymerase chain reaction (PCR). The results indicated that native rhizobia isolates from the Chascomús area are predominantly fast and intermediate-growers. The unclassified rhizobia examined by PCR-RFLP were found to be closely related to the reference strains of validly described Rhizobium species.
Assuntos
Lotus/microbiologia , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Rhizobium/classificação , Rhizobium/genética , Microbiologia do Solo , Argentina , Proteínas de Bactérias/química , DNA Bacteriano/análise , Genes de RNAr , RNA Ribossômico 16S/genética , Rhizobium/crescimento & desenvolvimento , Rhizobium/isolamento & purificação , SimbioseRESUMO
The lon gene of Escherichia coli encodes the lon (La) protease, which is associated with cellular protein degradation. A lon gene homolog from Azospirillum brasilense, a nitrogen-fixing soil bacterium which lives in association with the roots of cereal grasses, was cloned and characterized. The nucleotide sequence of the A. brasilense lon gene was determined. It contains an open reading frame that encodes a protein of 810 amino acids with a predicted molecular mass of about 90 kDa. The deduced amino acid sequence showed a high level of homology with the sequences of all the known lon gene products. An open reading frame homologous to the E. coli clpX gene was found in front of the lon gene. Transcriptional analysis showed that the lon gene of A. brasilense is induced by heat shock and that the mRNA is monocistronic. An A. brasilense mutant, with Tn5 inserted in the lon gene, was shown to be defective in iron uptake and failed to express two membrane proteins that are induced by iron starvation in the parental strain.