Wyniki wyszukiwania - Biblioteka Nauki

1

Fizjologiczna charakterystyka bakterii z rodzaju Azospirillum

100%

Krol M. J.

|

nr 6

3-20

EN

From the seven species: A. amazonense, A. halopraeferens, A. largimobile, A. irakense and A. doebereinerae, that had been described, A. brasilense and A. lipoferum were isolated all over the word from soil and the roots a variety of grasses and cereals. These bacteria are aerobic nonfermentative chemoorganotrophs. They are Gram negative, the cells are vibrioid to S-shaped, mobile in liquid media by a polar flagellum. On solid media, A. brasilense, A. lipoferum and A. irakense have the lateral flagellae. In case of Azospirillum spp. the formation of cyst-like structures in old cultures was described. They contain granules of poly-ß-hydroxybutyrate (PHB). Azospirillum spp. synthesize exopolysaccharides and capsular polysaccharides. The G + C content in DNA varies between 64 and 70 mol%. Their optimum growth temperature ranges from 28° to 41°C. In general, the bacteria of Azospirillum genus utilize a variety of sugars, alcohols and organic acids as carbon sources. A. irakense grows with pectin as the sole carbon source. Autotrophic growth under aerobic conditions, with H₂ as the energy source has been demonstrated for A. lipoferum. Azospirillum spp. can utilize the ammonia and nitrate, most strains of A. brasilense and A. lipoferum are denitrifiers, whereas A. amazonense and A. irakense are reported to be unable to denitrify. From other physiological properties, they can produce siderophores, phytohormones and other plant growth-promoting substances.

2

Interakcje Azospirillum spp. z mikroorganizmami glebowymi

100%

Krol M. J.

|

nr 5

3-13

EN

Inoculation of various plants with Azospirillum spp. caused remarkable changes in the morphology of their root systems and a positive increase in plant growth when applied in combination with microsymbionts, such as VA-mycorrhizal fungi or Rhizobium. At concentration of 10⁸ cfu per plant the Azospirillum spp. stimulated the appe-roots arance of lateral roots and enhanced the appearance and number of adventitious roots as compared to non treated controls. Positive influence of Azospirillum spp. on the VA-mycorrhiza-plant symbiosis seemed to be less sensitive to circumstantial factors than the legume-Rhizobium symbiosis. The literature review mentioned that the two bacteria, Azospirillum and Rhizobium, may be competing with one another in the legume rhizosphere, thereby inhibiting nodule formation. VA mycorrhizal fungi-plant symbiosis and legume-Rhizobium symbiosis are two systems in which Azospirillum can improve the symbiotic performance of each of the microorganisms and potentially increase crop yields.

3

III Turniej Tenisowy Cukiernikow i Piekarzy

75%

Krol M. J.

|

tom 50

|

nr 11

72

4

Wytwarzanie zwiazkow chelatujacych Fe[III] przez bakterie z rodzaju Azospirillum

63%

Krol M. J. , Perzynski A.

|

2001

|

tom 88

125-131

5

Wykorzystanie benzenu jako jedynego źródła węgla w wiązaniu wolnego azotu przez bakterie z rodzaju Azospirillum i Pseudomonas stutzeri

63%

Krol M. J. , Pierzynski A.

|

tom 140

6

Szczepy bakterii Pseudomonas stutzeri wyizolowanej z endoryzosfery jeczmienia i wydmuchrzycy piaskowej

51%

Krol M. J. , Perzynski A. , Eckert B.

|

2002

|

tom 90

83-89

7

N2-fixing bacteria isolated from the roots of crops and grasses

51%

Krol M. J. , Perzynski A. , Kobus J.

|

2001

|

tom 52

EN

Free-living bacteria fixing-N2 (from genera of Azospirilliim and Acinetobacter- like) occurred in the rhizosphere of barley, cultivated on different soils and also in the rhizosphere of maize and grasses grown on medium alluvial soil. In the rhizosphere of barley occurrence of Azospirilliim sp. strains was found in 84%, and in the rhizosphere of maize and grasses in the amount of 100% and 94%, respectively. Bacteria of the genus Azospirillum were not found in the rhizosphere of Lolium perenne, Phleum pratense and Poa palustris. In the rhizosphere of barley cultivated on rendzinas and black earth developed from slightly loamy sand and in the rhizosphere of grasses, were found of halophylic strains of Azospirillum sp. (growth in medium with 3% NaCl) and strains, which preliminary determined as Acinelobacter-like (growth in medium with 6% NaCl). The most probable number (MPN) of bacteria from the genus Azospirillum counted in the rhizosphere of barley, maize and grasses ranged from 0 to 2450 cells g-1 of soil dry matter. No correlation between the frequency of their occurrence and content of available components, humus and exchangeable cations in the soil sampling date was observed. The nitrogenase activity of Azospirillum spp. strains isolated from the barley, maize and grasses rhizosphere ranged from 1.6 to 228.5 nM C2H4 h-1 cm-3 of gas phase. The nitrogenase activity of the isolated Acinetobacter-like strains ranged from 8,4 to 59,4 nM C2H4 h-1cm-3 of the gas phase.