Cysts of Azospirilla Under Various Cultural Conditions

Sadasivan, Lakshmi; Neyra, Carlos A.

doi:10.1007/978-3-642-70791-9_22

Cited by 7 publications

(5 citation statements)

References 17 publications

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“…Azospirillum brasilense strains are known to be highly pleomorphic and to change their metabolic activities swiftly in response to changes in environmental conditions (7,14,28,29). Under low oxygen tension, bacteria of the genus Azospirillum are highly motile, half-curved or vibrioid, gram-negative rods with a long polar flagellum in liquid medium and additional peritrichous flagella on solid medium (35).…”

mentioning

confidence: 99%

“…Under low oxygen tension, bacteria of the genus Azospirillum are highly motile, half-curved or vibrioid, gram-negative rods with a long polar flagellum in liquid medium and additional peritrichous flagella on solid medium (35). Under aerobic conditions, particularly in aged cultures, vibrioid cells undergo a transition to round, nonmotile, encapsulated forms (7,14) that are considered to be cysts (21,28,29,30). Heavy capsulation gives the cells a particular adhesive nature so that they aggregate in a matrix of polysaccharide material, forming large macroscopic clumps that flocculate in liquid cultures (28).…”

mentioning

confidence: 99%

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Mutants with Enhanced Nitrogenase Activity in HydroponicAzospirillum brasilense-Wheat Associations

Gerk

Gilchrist

Kennedy

2000

Appl Environ Microbiol

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The effect of a mutation affecting flocculation, differentiation into cyst-like forms, and root colonization on nitrogenase expression by Azospirillum brasilense is described. The gene flcA of strain Sp7 restored these phenotypes in spontaneous mutants of both strains Sp7 and Sp245. Employing both constitutive pLA-lacZ and nifH-lacZ reporter fusions expressed in situ, the colony morphology, colonization pattern, and potential for nitrogenase activity of spontaneous mutants and flcA Tn5-induced mutants were established. The results of this study show that the ability of Sp7 and Sp245 mutant strains to remain in a vegetative form improved their ability to express nitrogenase activity in association with wheat in a hydroponic system. Restoring the cyst formation and colonization pattern to the spontaneous mutant Sp7-S reduced nitrogenase activity rates in association with plants to that of the wild-type Sp7. Although Tn5-induced flcA mutants showed higher potentials for nitrogenase expression than Sp7, their potentials were lower than that of Sp7-S, indicating that other factors in this strain contribute to its exceptional nitrogenase activity rates on plants. The lack of lateral flagella is not one of these factors, as Sp7-PM23, a spontaneous mutant impaired in swarming and lateralflagellum production but not in flocculation, showed wild-type nitrogenase activity and expression. The results also suggest factors of importance in evolving an effective symbiosis between Azospirillum and wheat, such as increasing the availability of microaerobic niches along the root, increased supply of carbon sources by the plant, and the retention of the bacterial cells in vegetative form for faster metabolism.

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confidence: 99%

mentioning

confidence: 99%

Mutants with Enhanced Nitrogenase Activity in HydroponicAzospirillum brasilense-Wheat Associations

Gerk

Gilchrist

Kennedy

2000

Appl Environ Microbiol

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“…The culture of azospirilla was grown on a liquid synthetic medium for flocculation at 37 o C for 24 h [10].…”

Section: Methodsmentioning

confidence: 99%

In Vitro Effect of Fucose-Specific Lectins on Rat Erythrocyte Membranes under Normal Conditions and during Toxic Stress

et al. 2005

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We studied the effect of various fucose-specific lectins on lipid peroxidation in rat erythrocyte membranes under normal conditions and during exposure to the toxic agent. Under normal conditions parameters of lipid peroxidation in erythrocyte membranes increased after treatment with lectins or cadmium nitrate. Lectins possess biological activity modulated lipid peroxidation in membranes of erythrocytes from experimental animals, which depended on the time of adaptation. Differences were revealed in the effect of bacterial and plant lectins on lipid peroxidation in erythrocytes treated with the test xenobiotic.

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“…By pectolytic enzymes, some azospirilla are able to penetrate to intercellular spaces of root cortex cells (Umali- Garcia et al 1980). High resistance against drought and freezing (Jagnow 1982) can be caused by the formation of resting cysts ( Lamm andNeyra, 1981, Sadasivan andNeyra 1985).…”

Section: Significance Of Specificity and Adaptation Of Bacteria For Cmentioning

confidence: 99%

Inoculation of cereal crops and forage grasses with nitrogen‐fixing rhizosphere bacteria: Possible causes of success and failure with regard to yield response – a review

Jagnow

1987

J Plant Nutrition & Soil

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Recent field inoculation trials with Azospirillum and Azotobacter spp. applied to cereal and forage crops have shown extremely different results in yield response. Some aspects of bacteria‐plant interactions affecting yield response are discussed. These include provision of fixed nitrogen, specificity and adaptation to root habitat, influence of microbial metabolites, enhancement of VA‐mycorrhiza, displacement of deleterious rhizosphere microorganisms, differences between host plant genotypes, competitive ability and longevity of inoculants. Based on these considerations, needs for further research will be outlined.

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Cysts of Azospirilla Under Various Cultural Conditions

Cited by 7 publications

References 17 publications

Mutants with Enhanced Nitrogenase Activity in HydroponicAzospirillum brasilense-Wheat Associations

Mutants with Enhanced Nitrogenase Activity in HydroponicAzospirillum brasilense-Wheat Associations

In Vitro Effect of Fucose-Specific Lectins on Rat Erythrocyte Membranes under Normal Conditions and during Toxic Stress

Inoculation of cereal crops and forage grasses with nitrogen‐fixing rhizosphere bacteria: Possible causes of success and failure with regard to yield response – a review

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