Release of microorganisms from soil with respect to transmission electron microscopy viewing and plate counts

Balkwill, David L.; Rucinsky, Thomas E.; Casida, L. E.

doi:10.1007/bf02316212

Cited by 28 publications

(11 citation statements)

References 20 publications

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“…Compared with the sum of counts in the residue of the homogenized soil plus the Percoll [7.5 (s.d.kO.9) x 107/g], this gave a recovery of 71%. The high recovery of Serratia compared to native soil micro-organisms parallels the result of a centrifugal recovery experiment with Arthrobacter added to a soil homogenate (Balkwill et al 1977) and suggests that added cells are more easily removed than native soil micro-organisms. The ratio of total Serratia recovered: Serratia added per gram of soil was 1.09 indicating that no cell death occurred during the extraction procedure.…”

Section: Viability Of Micro-organisms In Percollmentioning

confidence: 54%

“…marcescens. After homogenization for 4 rnin at the 'medium' setting on a Vertis '45' blendor (Vertis Research Equipment, Gardiner, New York), the soil suspension was centrifuged once with programmed acceleration (Balkwill et al 1977). The suspension was sedimented for 2 min at each of N 80, N 3 15, N 700 and N 940 g; it was finally held at 2.6350 g for 10 min.…”

Section: Recovery Of Serratia Marcescens From Soilmentioning

confidence: 99%

“…(2) Toxicity, e.g. Ludox (colloidal silica); this problem has restricted the use of unmodified colloidal silica to the preparation of soil micro-organisms for electron microscopy (Balkwill et al 1977). (3) Viscosity, e.g.…”

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confidence: 99%

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Separation of Non‐filamentous Micro‐organisms from Soil by Density Gradient Centrifugation in Percoll

Martin¹,

Macdonald

1981

Journal of Applied Bacteriology

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Soil suspensions were homogenized, and desorbed non‐filamentous micro‐organisms were concentrated in a minimum volume of buffer by low speed centrifugation. The cells were separated from inanimate material by flotation at the interface between the buffer and a silica sol/polyvinyl pyrrolidone density gradient medium (Percoll). Cell suspensions were removed from the interface and fractionated according to density by high speed centrifugation on discriminating density gradients in Percoll. Preliminary experiments indicated that most non‐filamentous soil micro‐organisms had densities in the range 1.081–1.123 g%sol;ml while Rhizobium isolated from crushed root nodules on Percoll was split into two bands of densities 1.081–1.110 and 1.041–1.073 g/ml. The lighter cells were the more pleomorphic. The efficiency of extraction of cells from soil was governed by the extent of their desorption from inanimate particles. As rigorous desorption procedures damage cells, extraction efficiencies were low; 10–20% of cells counted microscopically in soil were recovered from density gradients. Electron microscopy of soil micro‐organisms isolated by this method showed an unusual range of surface ornamentations on cell‐like structures of bacterial dimensions.

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Section: Viability Of Micro-organisms In Percollmentioning

confidence: 54%

Section: Recovery Of Serratia Marcescens From Soilmentioning

confidence: 99%

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Separation of Non‐filamentous Micro‐organisms from Soil by Density Gradient Centrifugation in Percoll

Martin¹,

Macdonald

1981

Journal of Applied Bacteriology

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“…These interactions were probably mediated by physicochemical forces, and they appeared to be reversible. Therefore, they did not resemble the firm microbial attachment reported for natural soil (6).…”

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confidence: 67%

Attachment to Autoclaved Soil of Bacterial Cells from Pure Cultures of Soil Isolates

Balkwill

Casida

1979

Appl Environ Microbiol

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Pure cultures of Arthrobacter globiformis and four fresh soil isolates were incubated individually in autoclaved soil, in both the presence and absence of glucose. These bacteria grew in the soil and, except for A. globiformis, eventually attached firmly to the soil solids. Firmly attached cells were defined as those which could not be separated from the soil solids by blending combined with a series of low-speed centrifugal washings. The attachment attained by the soil isolates appeared to duplicate that of the overall bacterial population that resides naturally in unaltered, unamended soil. Cell attachment in the autoclaved-soil system was accelerated slightly by glucose, but, except for one soil isolate, several months of incubation were still required before firm attachment was complete. Electron microscopy indicated that all attached cells produced extracellular polysaccharide slimes in the autoclaved soil and that these materials appeared to connect the cells to surrounding pieces of soil debris. The actual role of polysaccharides in attachment was not clear, however, because at least one of these organisms possessed extracellular slime during the long period in which it had not yet attached to the soil.

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“…Neutrophilic and acidophilic heterotrophic bacteria were enumerated by traditional spread plate analyses on solid agar media. Total viable counts for neutrophilic, heterotrophic microorganisms were determined in triplicate by adding 1.0 g of sediment to 9.0 ml of sterile 0.1% (wt/vol) sodium pyrophosphate dilution buffer (pH 7.0) (4) (25). Acidophilic bacteria were enumerated by the method of Harrison (9).…”

Section: Methodsmentioning

confidence: 99%

Biodegradation of Aromatic Hydrocarbons in an Extremely Acidic Environment

Stapleton

Savage²,

Sayler

et al. 1998

Appl Environ Microbiol

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The potential for biodegradation of aromatic hydrocarbons was evaluated in soil samples recovered along gradients of both contaminant levels and pH values existing downstream of a long-term coal pile storage basin. pH values for areas greatly impacted by runoff from the storage basin were 2.0. Even at such a reduced pH, the indigenous microbial community was metabolically active, showing the ability to oxidize more than 40% of the parent hydrocarbons, naphthalene and toluene, to carbon dioxide and water. Treatment of the soil samples with cycloheximide inhibited mineralization of the aromatic substrates. DNA hybridization analysis indicated that whole-community nucleic acids recovered from these samples did not hybridize with genes, such asnahA, nahG, nahH,todC1C2, and tomA, that encode common enzymes from neutrophilic bacteria. Since these data suggested that the degradation of aromatic compounds may involve a microbial consortium instead of individual acidophilic bacteria, experiments using microorganisms isolated from these samples were initiated. While no defined mixed cultures were able to evolve14CO2 from labeled substrates in these mineralization experiments, an undefined mixed culture including a fungus, a yeast, and several bacteria successfully metabolized approximately 27% of supplied naphthalene after 1 week. This study shows that biodegradation of aromatic hydrocarbons can occur in environments with extremely low pH values.

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Release of microorganisms from soil with respect to transmission electron microscopy viewing and plate counts

Cited by 28 publications

References 20 publications

Separation of Non‐filamentous Micro‐organisms from Soil by Density Gradient Centrifugation in Percoll

Separation of Non‐filamentous Micro‐organisms from Soil by Density Gradient Centrifugation in Percoll

Attachment to Autoclaved Soil of Bacterial Cells from Pure Cultures of Soil Isolates

Biodegradation of Aromatic Hydrocarbons in an Extremely Acidic Environment

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