The potential for N(2) fixation by heterocystous cyanobacteria isolated from soils of different geographical areas was determined as nitrogenase activity (NA) using the acetylene reduction assay. Morphology of cyanobacteria had the largest influence on NA determined under light conditions. NA was generally higher in species lacking thick slime sheaths. The highest value (1446 nmol/h C(2)H(4) per g fresh biomass) was found in the strain of branched cyanobacterium Hassalia (A Has1) from the polar region. A quadratic relationship between NA and biomass was detected in the Tolypothrix group under light conditions. The decline of NA in dark relative to light conditions ranged from 37 to 100 % and differed among strains from distinct geographical areas. Unlike the NA of temperate and tropical strains, whose decline in dark relative to light was 24 and 17 %, respectively, the NA of polar strains declined to 1 % in the dark. This difference was explained by adaptation to different light conditions in temperate, tropical, and polar habitats. NA was not related to the frequency of heterocysts in strains of the colony-forming cyanobacterium Nostoc. Colony morphology and life cycle are therefore more important for NA then heterocyst frequency. NA values probably reflect the environmental conditions where the cyanobacterium was isolated and the physiological and morphological state of the strain.
No significant differences in the acetylene-reducing activity and evolution of H2 and CO2 from nodulated roots of Pisum sativum inoculated with soil Rhizobium populations from two soils with different acidities (Ruzynĕ soil 7.6; Lukavec soil 4.9) were observed. Rhizobium population from Lukavec soil formed nodules, exhibiting a higher H2 evolution. Co-inoculation with the Hup+ strain 128C30 (7 x 10(7) cells per seedling) eliminated, to some extent, the effect of soil populations on physiological activity.
- MeSH
- acetylen metabolismus MeSH
- Fabaceae metabolismus mikrobiologie MeSH
- fixace dusíku * MeSH
- léčivé rostliny * MeSH
- nitrogenasa metabolismus MeSH
- oxid uhličitý metabolismus MeSH
- půdní mikrobiologie * MeSH
- Rhizobium leguminosarum metabolismus MeSH
- Rhizobium růst a vývoj metabolismus MeSH
- symbióza MeSH
- vodík metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
