Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Responses by iron-efficient and inefficient oat cultivars to inoculation with siderophore-producing bacteria in a calcareous soil (1993)
    Springer
    Biology and fertility of soils 16 (1993), S. 118-124 
    Details
    ISSN: 1432-0789
    Keywords: Siderophores ; Rhizosphere bacteria ; Pseudomonas ; Iron uptake ; Oats ; Inoculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rhizosphere bacteria may enhance plant uptake of Fe by producing siderophores that chelate sparingly soluble Fe3+ in calcareous soils. To evaluate the extent to which plants benefit from colonization of the roots by prolific siderophore-producing bacteria, we inoculated two oat cultivars with six strains of bacteria that produced high concentrations of siderophores under Felimiting conditions in vitro. Oat cv Coker 227, an Fe-efficient cultivar, which produces the phytosiderophore avenic acid, and cv TAM 0-312, and Fe-inefficient cultivar, which does not produce the phytosiderophore, were grown in a calcareous soil (Weswood silt loam) on a light bench in the laboratory. Half of the plants were fertilized with a nutrient solution containing 5 mM Fe and half with a nutrient solution containing no Fe. After 6 weeks of growth, we compared colonization of the roots by the inoculant bacteria and the dry weight and Fe content of roots and shoots. Three species of Pseudomonas colonized the roots of both oat cultivars in high numbers (≥106 cells g-1 root dry weight), whereas the remaining bacteria colonized the roots in substantially lower numbers (≤104 cells g-1 root dry weight). Plants fertilized with 5 mM Fe were larger and supported greater numbers or rhizosphere bacteria per gram of root than plants not supplied with Fe. Comparisons of the Fe content and dry weight of roots and shoots revealed few significant differences between inoculated and uninoculated plants, or among the plants inoculated with the different strains of siderophore-producing bacteria. The differences that were observed revealed no consistent response to inoculation. We conclude that inoculation of the roots of the two oat cultivars with bacteria that produce high concentrations of siderophores in response to an Fe deficiency had little or no effect on Fe acquisition by the plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00369412
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Use of chrome azurol S reagents to evaluate siderophore production by rhizosphere bacteria (1991)
    Springer
    Biology and fertility of soils 12 (1991), S. 39-45 
    Details
    ISSN: 1432-0789
    Keywords: Siderophores ; Rhizosphere bacteria ; Chrome azurol S reagent ; Fe dissolution ; Fe uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Siderophores produced by rhizosphere bacteria may enhance plant growth by increasing the availability of Fe near the root or by inhibiting the colonization of roots by plant pathogens or other harmful bacteria. To examine the populations of siderophore-producing bacteria colonizing the roots of two grass species that differed in their susceptibility to Fe deficiency, we inoculated serial dilutions of root samples onto chrome azurol S (CAS) agar and several other selective and non-selective culture meida. CAS agar effectively differentiated bacteria that were capable of excreting large amounts of siderophore, but the composition of the medium limited its usefulness for ecological studies. A large proportion (71–79%) of the bacterial population that grew on a non-selective medium (tryptic soy agar) failed to grow on CAS agar, and several isolates that showed no sign of siderophore production on CAS agar produced siderophore in liquid culture. Similar populations of siderophore-producing bacteria were observed on roots of St. Augustine grass, which frequently exhibits Fe chlorosis, and bermuda grass, which does not. Roots of both grasses were colonized by bacteria that produced siderophore in vitro at concentrations ranging from 100 to 230 μM. The CAS assay solution was also used to compare siderophore production by Pseudomonas fluorescens Q6, an isolate from bermuda grass, and by P. putida B 10, a plant growth-promoting pseudomonad. P. fluorescens Q6 produced 2.4 times more siderophore in vitro than P. putida B 10.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00369386
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Impact of soil environmental factors on rates of N2-fixation associated with roots of intact maize and sorghum plants (1988)
    Springer
    Plant and soil 110 (1988), S. 303-315 
    Details
    ISSN: 1573-5036
    Keywords: ammonium ; carbon ; inoculation ; nitrite ; nitrate ; oxygen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We have evaluated the effects of oxygen partial pressure (pO2), combined nitrogen, and the availability of organic substrates on nitrogen fixation (acetylene reduction) by bacteria associated with the roots of intact maize and sorghum plants. We also investigated the possibility of enhancing associative nitrogen-fixation by inoculating the soil in which the plants were grown withAzospirillum. Acetylene reduction (AR) activity was greatest when roots of intact plants were exposed to pO2 between 1.3 and 2.1 kPa. Field-grown and greenhouse-grown plants supported similar levels of activity. Respiration inhibitors (2,4-dinitrophenol and sodium azide) eliminated AR activity at 2 kPa O2, whereas a fermentation inhibitor (sodium fluoride) only partially reduced the activity. Acetylene reduction activity was rapidly (1–3 h) inhibited by NH 4 + , NO 3 − , and NO 2 − at concentrations of 4–20 mg Nl−1. Rates of AR varied substantially among individual plants in each experiment and between experiments. Amendment with any of several organic substrates greatly increased AR activity when rates were low, suggesting that the lack of activity was caused by a shortage of available carbon in the rhizosphere. Inoculation withAzospirillum failed to increase rates of AR associated with maize plants. In several experiments the indigenous bacteria associated with uninoculated plants exhibited greater activity than the bacteria associated with inoculated plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02226811
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Effects of organic substrates and chloramphenicol or nalidixic acid on acetylene reduction associated with roots of intact maize and sorghum plants (1988)
    Springer
    Plant and soil 112 (1988), S. 61-67 
    Details
    ISSN: 1573-5036
    Keywords: acetylene reduction ; nitrogen fixation ; organic substrates ; oxygen partial pressure ; Sorghum bicolor ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To study the role or organic substrate availability as a factor limiting associative N2-fixation we measured acetylene reduction (AR) associated with roots of intact maize and sorghum plants before and after adding organic substrates to the nutrient solution in a hydroponic system. Chloramphenicol (Cam) or nalidixic acid (NA) was added along with the substrate to determine whether bacterial protein synthesis or cell replication was necessary to support increased AR following amendment. The grasses were grown in pots in a greenhouse or on a light bench for 4–6 weeks, and then brought into the laboratory to measure AR. Intact plants were separated from soil and transferred into plastic cylinders containing an N-free nutrient solution. The roots were isolated from the shoots by a silicone rubber seal and exposed to oxygen concentrations of 0–10 kPa. Rates of AR were measured before and after adding 0.01–0.10% (w/v) carbon as glucose, malate, succinate, ethanol, acetate, glutarate, propionate, or resorcinol. Only resorcinol and ethanol failed to substantially increase AR activity. Rates of AR increased by 1.5-to 2-fold within 2h and by 5-to 15-fold after 24h. Cam and NA prevented the stimulation of AR by glucose, but neither inhibitor caused AR associated with unamended plants to decrease. We conclude that the highly variable rates of AR that have been reported for associative symbioses, even under well-controlled conditions were governed to a large extent by the amount and type of organic substrates exuded by the roots. Proliferation of diazotrophs appeared to be necessary to increase root-associated AR activity but not to maintain a constant level of activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02181753
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Effects of oxygen partial pressure and combined nitrogen on N2-fixation (C2H2) associated withZea mays and other gramineous species (1986)
    Springer
    Plant and soil 90 (1986), S. 47-58 
    Details
    ISSN: 1573-5036
    Keywords: Acetylene reduction ; Ammonium ; Corn ; Oxygen partial pressure ; Pearl millet pO2 ; Sorghum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The objectives of this investigation were to determine the effects of oxygen partial pressure (pO2) and combined nitrogen (NH 4 + ) on rates of acetylene reduction (AR) associated with roots of intact corn, sorghum, and pearl millet plants. Soil-grown plants were carefully removed from soil and incubated hydroponically with the root system enclosed in a plastic cylinder; the tops were left exposed to ambient conditions. Oxygen concentrations around the root systems were controlled by sparging the nutrient solution with known quantities of O2 in N2. Ammonium nitrogen was added to the nutrient solution following establishment of AR rates to determine its effect on rates of N2-fixation (AR). Substantial AR rates (0.1–1.5 μmol C2H4 g dry wt−1 h−1) were associated with roots exposed to 0–2% O2 (v/v) (0.0–2.02 kPa) in N2 following at 12–24 h period of exposure to the reduced oxygen tension. Root systems exposed to air failed to demonstrate AR while those exposed to 100% N2 showed lower activity than those at reduced pO2 values. Addition of NH 4 + (10–20 μg N ml−1 of nutrient solution) reduced AR by 75–90% within 24 h after addition. Oxygen uptake by roots exposed to low pO2 was substantially reduced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02277386
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Growth kinetics of top and bottom cultures of Saccharomyces spp. in a chemostat using sugarbeet molasses (1988)
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 8 (1988), S. 115-123 
    Details
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Growth kinetics were evaluated for three yeast strains of the genus Saccharomyces. Two topfloating strains, SF 115 and SF 116 and one flocculant yeast SF 104 were analyzed in pure and mixed cultures in 1-liter continuous fermentation experiments in a chemostat. Growth was monitored for 72 h at 30°C in a medium containing sugarbeet molasses and 1.0 g/liter each of NH4H2PO4 and urea. SF 115 and SF 116 were found to have lower μmax values of 0.290 and 0.296 h-1, respectively, than SF 104, which had a μmax of 0.364 h-1. The two top-floating yeasts (SF 115 and SF 116) demonstrated greater affinity for the substrate and utilized substrates at a greater rate. They have K8 values of 4.03 × 10-3 M and 3.798 × 10-3 M, respectively, compared to 9.06 × 10-3 M for SF 104. A mixed culture of SF 116 and SF and SF 104 was found to have a μmax of 0.426 h-1 with a Ks of 6.924 × 10-3 M. SF 115 grown in mixed culture with SF 104 exhibited a μmax of 0.473 h-1 with a Ks of 7.975 × 10-3 M. In both cases, the SF 104 was the dominant microbe in mixed culture systems.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/abio.370080202
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...