New Culture Medium Containing Ionic Concentrations of Nutrients Similar to Concentrations Found in the Soil Solution

Angle, J. S.; McGrath, S. P.; Chaney, Rufus L.

doi:10.1128/aem.57.12.3674-3676.1991

Cited by 85 publications

(26 citation statements)

References 11 publications

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“…The two types of growth media were based on salt‐solution‐equivalent (Angle et al ., ) buffered with 10 mM MES. pH was adjusted to values between 4.5 to 6.5 according to the pH of the original soil.…”

Section: Methodsmentioning

confidence: 99%

Determinants of Acidobacteria activity inferred from the relative abundances of 16S rRNA transcripts in German grassland and forest soils

Foesel

Nägele

Naether

et al. 2013

Environmental Microbiology

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16S rRNA genes and transcripts of Acidobacteria were investigated in 57 grassland and forest soils of three different geographic regions. Acidobacteria contributed 9-31% of bacterial 16S rRNA genes whereas the relative abundances of the respective transcripts were 4-16%. The specific cellular 16S rRNA content (determined as molar ratio of rRNA : rRNA genes) ranged between 3 and 80, indicating a low in situ growth rate. Correlations with flagellate numbers, vascular plant diversity and soil respiration suggest that biotic interactions are important determinants of Acidobacteria 16S rRNA transcript abundances in soils. While the phylogenetic composition of Acidobacteria differed significantly between grassland and forest soils, high throughput denaturing gradient gel electrophoresis and terminal restriction fragment length polymorphism fingerprinting detected 16S rRNA transcripts of most phylotypes in situ. Partial least squares regression suggested that chemical soil conditions such as pH, total nitrogen, C : N ratio, ammonia concentrations and total phosphorus affect the composition of this active fraction of Acidobacteria. Transcript abundance for individual Acidobacteria phylotypes was found to correlate with particular physicochemical (pH, temperature, nitrogen or phosphorus) and, most notably, biological parameters (respiration rates, abundances of ciliates or amoebae, vascular plant diversity), providing culture-independent evidence for a distinct niche specialization of different Acidobacteria even from the same subdivision.

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Section: Methodsmentioning

confidence: 99%

Determinants of Acidobacteria activity inferred from the relative abundances of 16S rRNA transcripts in German grassland and forest soils

Foesel

Nägele

Naether

et al. 2013

Environmental Microbiology

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“…The ground roots from the three different stages of cluster roots were 10‐fold serially diluted, and spread on Angle medium (Angle, McGrath & Chaney 1991) for plate counts and isolation of strains. Approximately 30 strains isolated from each cluster root stage were randomly selected and tested for their ability to grow in low‐pH media.…”

Section: Methodsmentioning

confidence: 99%

White lupin has developed a complex strategy to limit microbial degradation of secreted citrate required for phosphate acquisition

Weisskopf

Abou-Mansour

Fromin

et al. 2006

Plant Cell & Environment

169

116

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White lupins ( Lupinus albus L.) respond to phosphate deficiency by producing special root structures called cluster roots. These cluster roots secrete large amounts of carboxylates into the rhizosphere, mostly citrate and malate, which act as phosphate solubilizers and enable the plant to grow in soils with sparingly available phosphate. The success and efficiency of such a P-acquisition strategy strongly depends on the persistence and stability of the carboxylates in the soil, a parameter that is influenced to a large extent by biodegradation through rhizosphere bacteria and fungi. In this study, we show that white lupin roots use several mechanisms to reduce microbial growth. The abundance of bacteria associated with cluster roots was decreased at the mature state of the cluster roots, where a burst of organic acid excretion and a drastic pH decrease is observed. Excretion of phenolic compounds, mainly isoflavonoids, induced fungal sporulation, indicating that vegetative growth, and thus potential citrate consumption, is reduced. In addition, the activity of two antifungal cell wall-degrading enzymes, chitinase and glucanase, were highest at the stage preceding the citrate excretion. Therefore, our results suggest that white lupin has developed a complex strategy to reduce microbial degradation of the phosphate-solubilizing agents.

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“…The soil was air-dried, sieved to 2 mm size aggregates, homogenized and sterilized by autoclaving (1 h at 121°C for two consecutive days). Soil sterility was checked by spreading soil dilutions on Angle (Angle et al 1991) and Malt Agar media, and no microorganisms were detected. The soils were repacked in the microcosms (PVC tube; 35 cm height and 15 cm internal diameter) with a bulk density of 1.18 gcm −3 using the procedure of Boivin et al (2004).…”

Section: Experimental Setup Plant Mycorrhiza and Earthwormmentioning

confidence: 99%

Impact of two root systems, earthworms and mycorrhizae on the physical properties of an unstable silt loam Luvisol and plant production

et al. 2013

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Background and aims Soil organisms are known to engineer the soil physical properties, but their impact is difficult to assess and poorly documented. Shrinkage analysis has a good potential for such assessment. This study analyses the effects of mycorrhizae (Glomus intraradices), earthworms (Allolobophora chlorotica) and two plants, Allium porrum (leek) and Petunia hybrida (petunia), on the physical properties of an unstable loamy Luvisol, as well as the biological interactions between the soil organisms. Methods In addition to soil organism biomass, shrinkage analysis and soil aggregate stability analysis were used to characterize the soil physical properties. ResultsThe soil aggregate stability, specific volume and structural pores volumes were increased with plant roots compared to control. The drilling effect of roots could not explain the pore volume increase, which was several orders of magnitude larger than the volume of the roots. Leek had larger impact on volumes while petunia mostly increased soil aggregate stability. Mycorrhizae increased the soil stability and the soil volume. Earthworms alone decreased the pore volumes at any pore size, and plant roots mitigated this. Conclusions Our results highlight (1) the large impact of soil biota on soil physical properties, (2) that their separated effects can either combine or mitigate each other and (3) that the observed changes are varying in intensity according to soil type and plant type.

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New Culture Medium Containing Ionic Concentrations of Nutrients Similar to Concentrations Found in the Soil Solution

Abstract: A new growth medium which closely approximates the composition of the soil solution is presented. This soil solution equivalent (SSE) medium contains the following components (millimolar):

Cited by 85 publications

References 11 publications

Determinants of Acidobacteria activity inferred from the relative abundances of 16S rRNA transcripts in German grassland and forest soils

Determinants of Acidobacteria activity inferred from the relative abundances of 16S rRNA transcripts in German grassland and forest soils

White lupin has developed a complex strategy to limit microbial degradation of secreted citrate required for phosphate acquisition

Impact of two root systems, earthworms and mycorrhizae on the physical properties of an unstable silt loam Luvisol and plant production

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