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Journal ArticleDOI

Vital staining of fungi in pure cultures and in soil with fluorescein diacetate

01 Jan 1977-Soil Biology & Biochemistry (Elsevier)-Vol. 9, Iss: 1, pp 59-63
TL;DR: In experiments with pure cultures, good correlation was obtained between relative staining efficiency, growth rate, and respiration, and FDA appears to be a true vital stain, in that it stains only metabolically active mycelia.
Abstract: A method for vital staining of fungal mycelium with fluorescein diacetate (FDA) is described. In experiments with pure cultures, good correlation was obtained between relative staining efficiency, growth rate, and respiration. FDA thus appears to be a true vital stain, in that it stains only metabolically active mycelia. In fresh soil suspensions stained with FDA, brightly fluorescent hyphae and portions of hyphae were observed. The applicability of the method for measurement of active mycelium in the soil is discussed.
Citations
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Journal ArticleDOI
TL;DR: The respiratory method provides reproducible estimates of biomass size within 1–3 h after soil amendment, and can be combined without difficulty with a selective inhibition method for determination of bacterial and fungal contributions to soil metabolism.
Abstract: A method is described for the rapid and objective estimation of the amount of carbon in the living, non-resting microbial biomass of soils. The method, which is based on the initial respiratory response of microbial populations to amendment with an excess of a carbon and energy source, was quantified using an expanded version of Jenkinson's technique. The simultaneous application of the two methods to 50 soil samples showed a highly significant correlation (r = 0.96) between both. From this correlation it could be deduced that at 22°C, a substrate-induced maximal respiratory rate of 1 ml CO2· h−1 corresponds to c. 40 mg microbial biomass C. Evidence supporting these results was obtained from pure culture studies. The various soil types investigated were collected from agricultural as well as forest sites and they contained between 15 and 240 mg microbial C·100g dry soil−1. The respiratory method provides reproducible estimates of biomass size within 1–3 h after soil amendment. It can be combined without difficulty with a selective inhibition method for determination of bacterial and fungal contributions to soil metabolism.

2,787 citations

Journal ArticleDOI
TL;DR: Spectrophotometric determination of the hydrolysis of fluorescein diacetate (FDA) was shown to be a simple, sensitive, and rapid method for determining microbial activity in soil and litter.
Abstract: Spectrophotometric determination of the hydrolysis of fluorescein diacetate (FDA) was shown to be a simple, sensitive, and rapid method for determining microbial activity in soil and litter. FDA hydrolysis was studied in soil and straw incubated for up to 3 h. Hydrolysis was found to increase linearly with soil addition. FDA hydrolysis by pure cultures of Fusarium culmorum increased linearly with mycelium addition both in shake cultures and after inoculation into sterile soil. FDA hydrolysis by Pseudomonas denitrificans increased linearly with biomass addition. The FDA hydrolytic activities in soil samples from different layers of an agricultural soil were correlated with respiration. Acetone was found to be suitable for terminating the reaction.

1,176 citations


Cites background from "Vital staining of fungi in pure cul..."

  • ...Fluorescein diacetate (3',6'-diacetylfluorescein [FDA]) has been used to determine amounts of active fungi (14) and bacteria (1, 8) and to locate acetylesterases in living protist cells (10)....

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  • ...In the present investigation, no attempt was made to relate the observed total FDA activity to the active microbial biomass determined by FDA microscopic techniques (8, 14)....

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  • ...Earlier studies have shown that all fungi investigated (10, 14), most bacteria (8, 10), and some protozoa and algae (10) exhibit FDA hydrolytic activity....

    [...]

Journal ArticleDOI
TL;DR: The results support claims in the literature that microbial grazers may perform important regulatory functions at critical times in the growth of plants and support a conceptual model proposed in which microfloral grazers were considered as separate state variables.
Abstract: The most common system responses attributed to microfloral grazers (protozoa, nema- todes, microarthropods) in the literature are increased plant growth, increased N uptake by plants, decreased or increased bacterial populations, increased CO2 evolution, increased N and P mineral- ization, and increased substrate utilization. Based on this evidence in the literature, a conceptual model was proposed in which microfloral grazers were considered as separate state variables. To help evaluate the model, the effects of microbivorous nematodes on microbial growth, nutrient cycling, plant growth, and nutrient uptake were examined with reference to activities within and outside of the rhizosphere. Blue grama grass (Bouteloua gracilis) was grown in gnotobiotic microcosms containing sandy loam soil low in inorganic N, with or without chitin amendments as a source of organic N. The soil was inoculated with bacteria (Pseudomonas paucimobilis or P. stutzeri) or fungus (Fusarium oxysporum), with half the bacterial microcosms inoculated with bacterial-feeding nematodes (Pelodera sp. or Ac- robeloides sp.) and half the fungal microcosms inoculated with fungal-feeding nematodes (Aphelenchus avenae). Similar results were obtained from both the unamended and the chitin-amended experiments. Bacteria, fungi, and both trophic groups of nematodes were more abundant in the rhizosphere than in nonrhizosphere soil. All treatments containing nematodes and bacteria had higher bacterial densities than similar treatments without nematodes. Plants growing in soil with bacteria and bacterial-feeding nematodes grew faster and initially took up more N than plants in soil with only bacteria, because of increased N mineralization by bacteria, NH4+-N excretion by nematodes, and greater initial exploi- tation of soil by plant roots. Addition of fungal-feeding nematodes did not increase plant growth or N uptake because these nematodes excreted less NH4+-N than did bacterial-feeding nematode pop- ulations and because the N mineralized by the fungus alone was sufficient for plant growth. Total shoot P was significantly greater in treatments with fungus or Pelodera sp. than in the sterile plant control or treatments with plants plus Pseudomonas stutzeri until the end of the experiment. The additional mineralization that occurs due to the activities of microbial grazers may be sig- nificant for increasing plant growth only when mineralization by microflora alone is insufficient to meet the plants' requirements. However, while the advantage of increased N mineralization by mi- crobial grazers may be short-term, it may occur in many ecosystems in those short periods of ideal conditions when plant growth can occur. Thus, these results support other claims in the literature that microbial grazers may perform important regulatory functions at critical times in the growth of plants.

1,078 citations

Journal ArticleDOI
Pål Axel Olsson1
TL;DR: Various aspects of how the fatty acid signatures can be used for studies related to questions of biomass distribution and nutritional status of mycorrhizal fungi are discussed.

774 citations

Book ChapterDOI
26 Oct 2015
TL;DR: Dick et al. as mentioned in this paper discussed soil enzyme activities as a potential biochemical/biological indicator of soil quality and found that soil biological parameters may hold potential as early and sensitive indicators of soil ecological stress or restoration.
Abstract: With the increasing pressure to produce more food, fiber, and fuel to meet world demands on a limited land area, there is an unprecedented need to address global concerns about soil degradation. Understanding the underlying biological processes in tandem with identification of early warning indicators of ecosystem stress is needed to provide strategies and approaches for land resource managers and policymakers to promote long-term ecosystem sustainability. Biological and biochemically mediated processes in soils are fundamental to terrestrial ecosystem function. Ultimately, all members of the food web are dependent on the soil as a source of nutrients, and for degradation and cycling of complex organic compounds. Primary decomposers of organic matter provide energy that supports the activities of organisms from a number of trophic levels in soils. Historically, chemical and physical properties have been used as crude measures of soil productivity. Most notably, determination of soil organic matter has been related to general soil tilth. Soil organic matter changes very slowly, and therefore, many years may be required to measure changes resulting from perturbations. However, there is growing evidence that soil biological parameters may hold potential as early and sensitive indicators of soil ecological stress or restoration (Dick, 1992; Dick & Tabatabai, 1992). In Chapter 5 (this book) information is provided on soil quality in relation to soil microorganisms. In this chapter, soil enzyme activities will be discussed as a potential biochemical/biological indicator of soil quality.

640 citations

References
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Journal ArticleDOI
TL;DR: Soil micro-organisms have been counted by a new technique whose essential feature is the suspension of measured amounts of soil in a molten agar gel from which small drops are removed and allowed to solidify as thin films on a haemocytometer slide of known depth.
Abstract: SUMMARY: Soil micro-organisms have been counted by a new technique whose essential feature is the suspension of measured amounts of soil in a molten agar gel from which small drops are removed and allowed to solidify as thin films on a haemocytometer slide of known depth. The instantaneous gelation of the agar ensures the fixation of the soil constituents in their original distribution. The films are dried and stained in a solution of acetic-aniline blue and permanent preparations made by subsequent dehydration in ethanol and mounting in euparal. If the suspension is of known dilution, since films of a definite volume contain a known quantity of soil, differential counts of a measured area of film will yield a quantitative estimate of soil micro-organisms. The distribution of bacteria per microscopic field was found to be complex. The frequencies of bacterial colonies and of pieces of fungal mycelium form a Poisson series; those of the number of bacteria per colony form a logarithmic series; and those of the total number of bacteria per field fall into a negative binomial distribution. The method appears to be capable of modification by the use of selective nutrient media for determining the quality of the microflora and possibly the percentage viability of the organisms present.

355 citations

Journal ArticleDOI
TL;DR: The number of bacteria decreased in a linear fashion with depth but no relation was found between the numbers obtained by direct microscopy and those by plate counting, but each of the methods showed a high relationship between the size of the bacterial population present at each depth on the differe...
Abstract: Quantitative recoveries of bacteria added to a number of soils were obtained using fluorescein isothiocyanate (FITC) as a stain. Enzyme fluorescence, using fluorescein diacetate or dibutyrate, coul...

300 citations

Journal ArticleDOI
TL;DR: In this paper, the length of filamentous algae is estimated by superimposing a measuring grid upon the field either by a micrometer eyepiece or a ruled counting cell.
Abstract: One measure of the filamentous algae present in a microscope field is the total length of all the algal filaments. This is usually estimated by superimposing a measuring grid upon the field either by a micrometer eyepiece or a ruled counting cell. The inherent difficulty in such a method is in estimating lengths of segments making an acute angle with the lines of the grid. Just how this should be done is seldom stated in the directions for making counts. For instance, in the Areal Standard-unit Method, Whipple (1927) merely states: "Filamentous forms of constant width can be measured in lengths and then reduced to units by multiplying by the average diameter." The same idea is expressed by Welch (1948): "Some filamentous plankters have very constant diameters, hence counting is facilitated by determining the length in linear units of the individual filaments and then multiplying by the number representing the common diameter." Chandler (1940) likewise leaves the method of determining total length entirely up to the individual making the measurements. He employs for his phytoplankton analysis a unit system where, for example, one cell of Xavicula, four cells of Scenedesmus, 300 micra of Melosira, or 100 micra of Fragilaria each count as one unit.

238 citations