| 1. |
- Frostegård, Å, et al.
(författare)
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Microbial biomass measured as total lipid phosphate in soils of different organic content
- 1991
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Ingår i: Journal of Microbiological Methods. - 0167-7012. ; 14:3, s. 151-163
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Tidskriftsartikel (refereegranskat)abstract
- The use of total lipid phosphate as a measure of biomass was evaluated in soils with different organic matter content. Lipids were extracted with a one-phase mixture of chloroform, methanol, and a buffer, and digested with either persulfate or perchloric acid to liberate lipid-bound phosphate. This procedure was evaluated by varying the extraction buffer, the extraction and digestion times, the amount of soil extracted, and the amount of lipid material digested. An extraction period of 2 h was sufficient to yield maximum lipid phosphate. Neither sonication, vigorous mixing, nor longer extraction periods increased the amount of lipid phosphate extracted. However, the amount of lipid phosphate recovered was dependent on the choice of buffer. When organic soil was used, citrate buffer in the extraction mixture gave higher amounts of lipid phosphate than acetate buffer, Tris, H2O or phosphate buffer. In a sandy loam with low organic matter content, citrate or phosphate buffers performed equally well. When 13 soils of different organic matter content were examined, the two digestion methods showed a good linear correlation (r2 = 0.991). Substrate-induced respiration (SIR) and ATP contents of the different soils correlated well with the total lipid phosphate. Based on these measurements, a conversion factor of 500 μmol lipid phosphate·g-1 biomass-C (perchloric acid digestion) was calculated.
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| 2. |
- Nivens, David E., et al.
(författare)
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Monitoring microbiol adhesion and biofilm formation by attenuated total reflection/Fourier transform infrared spectroscopy
- 1993
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Ingår i: Journal of Microbiological Methods. - 0167-7012. ; 17:3, s. 199-213
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Tidskriftsartikel (refereegranskat)abstract
- A major problem in accurately defining bacterial adhesion mechanisms and processes occurring in biofilms on surfaces is the lack of techniques that nondestructively provide on-line information about the microorganisms, their extracellular polymers, and metabolites. The attenuated total reflectance (ATR) technique of Fourier transform infrared spectroscopy (FT-IR) is ideally suited to monitor molecular interactions at the solution/internal reflection element (IRE) interface, and we report its application to biofilm research. Two methodologies were utilized to obtain the ATF/FT-IR spectra of living Caulobacter crescentus cells attached to germanium crystals. Initially, spectra of attached bacteria in high purity water produced molecular details of the attachment process without spectral interferences from components of the medium. A growth medium, utilized in the second method, allowed direct examination of the infrared absorption bands associated with the actively growing microorganisms on the surface of the IRE in the spectral region of 2000 to 1200 cm-1. Using the amide II band as a marker for biofilm biomass, the detection limit was determined to be approximately 5 × 105 cells·cm-2. These results proved that the ATR-FT/IR methodologies can be utilized to provide chemical information from bacteria and bacterial products located within approximately 1 μm of the surface without spectral interferences due to components of the medium.
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| 3. |
- Odham, Goran, et al.
(författare)
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Determination of microbial fatty acid profiles at femtomolar levels in human urine and the initial marine microfouling community by capillary gas chromatography-chemical ionization mass spectrometry with negative ion detection
- 1985
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Ingår i: Journal of Microbiological Methods. - : Elsevier BV. - 0167-7012. ; 3:5-6, s. 331-344
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Tidskriftsartikel (refereegranskat)abstract
- Room temperature esterification with the electron capturing pentafluorobenzyl bromide in glass capillaries, with analysis by capillary gas-liquid chromatography coupled with chemical ionization mass spectrometry and negative ion detection in the selected ion mode, allowed detection and identification of fatty acids from microbial biofilms at the femtomolar level. This sensitivity was achieved without loss of specificity of the mass spectrometric analysis. The detection of all the fatty acids commonly associated with bacteria was quantitative and linearly related to their concentration at a sensitivity permitting detection of about 600 bacteria the size of Escherichia coli. With this technique it was possible to detect the characteristic 3-hydroxy fatty acid of the lipopolysaccharide lipid A of E. coli infecting human urine at concentrations representing 10 4 bacteria and define the community structure of the initial marine microfouling community attached to a teflon surface at concentrations below the detectability by gas chromatography with flame ionization detection.
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| 4. |
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| 5. |
- Szponar, Bogumila, et al.
(författare)
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Limitations in the use of 3-hydroxy fatty acid analysis to determine endotoxin in mammalian samples
- 2002
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Ingår i: Journal of Microbiological Methods. - 1872-8359 .- 0167-7012. ; 50:3, s. 283-289
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Tidskriftsartikel (refereegranskat)abstract
- 3-Hydroxy fatty acids (3-OH FAs) of 10-18-carbon chain lengths are constituents of the lipopolysaccharide of Gram-negative bacteria. These acids are used as chemical markers for determining endotoxin in environmental samples. The present communication addresses the question whether this type of analysis also would be applicable to mammalian samples. Low levels (6.1 +/- 1.6-94.0 +/- 23.2 pmol/ml) of the studied 3-OH FAs were detected in blood from both conventional and germ-fine rats. The levels were considerably higher (0.0-1.06 +/- 0.17 nmol/mg) in livers. The amounts of the 3-OH FAs did not differ between the two groups of rats. All analyses were made by gas chromatography-tandem mass spectrometry (GC-MSMS) for unequivocal identification. The results illustrate a limitation in using 3-OH FA analysis to determine endotoxin in mammalian samples since these acids may represent not only endotoxin but also products from mammalian mitochondrial fatty acid beta-oxidation. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 6. |
- Tunlid, Anders, et al.
(författare)
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Capillary gas chromatography using electron capture or selected ion monitoring detection for the determination of muramic acid, diaminopimelic acid and the ratio of d/l-alanine in bacteria
- 1983
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Ingår i: Journal of Microbiological Methods. - : Elsevier BV. - 0167-7012. ; 1:2, s. 63-76
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Tidskriftsartikel (refereegranskat)abstract
- Gas chromatographic analyses of muramic acid, diaminopimelic acid and D-alaline, which are specific components of the bacterial cell wall, have been performed using electron capture or selected ion monitoring detection. Intact cells or peptidogylycan preparations were hydrolyzed in HCl and DCl. After purification by cation exchange chromatography, followed by conversion to the N-heptafluobutyrliso-butyl esters, the components were separated on a 25 m fused silica column coated with SE-54 or on a chiral glass capillary column. The detection limits for muramic acid and diaminopimelic acid were about 10 pg using either detection method and the procedure has the potential sensitivity for detecting about 3 × 105 bacterial cells, e.g., Escherichia coli. Mass spectrometric determination of the d/l ratio of alamine in intact cells of Group A streptococci, type M 15 and in peptidogylcan preparations thereof indicated the proportions 10.2% and 10.5% of D-alanine, respectively. The values uncorrected for racemization during acid hydrolysis were 10.3% and 10.7%, respectively.
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| 7. |
- Tunlid, Anders, et al.
(författare)
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Determination of 13C-enrichment in bacterial fatty acids using chemical ionization mass spectrometry with negative ion detection
- 1987
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Ingår i: Journal of Microbiological Methods. - : Elsevier BV. - 0167-7012. ; 7:2-3, s. 77-89
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Tidskriftsartikel (refereegranskat)abstract
- Saturated, monoenoic and β-hydroxysubstituted fatty acids, 13C-labelled at the carboxyl group, were prepared from natural or synthetic unlabelled analogues. The synthetic route involves decarboxylation of the unlabelled fatty acid to the next lower iodide, displacement of iodide for [13C]cyanide and hydrolysis. The fatty acids were converted to their pentafluorobenzyl esters and analysed by selected ion monitorint using chemical ionization and negative ion detection. Measurements of the signal ratios for the negative carboxylate ion (m) and the (m + 1) ion showed that at 95% confidence level and n = 5, mean values differing by 1.0 atom% 13C will be significantly resolved. The calculated standard deviation was the same for the studied bacterial acids including the phospholipid ester-linked palmitoleic acid, β-hydroxymyristic acid in the lipopolysaccharides and β-hydroxybutyric acid in the storage polymer poly-β-hydroxyalkanoate. Sodium [1-13C]acetate or D-[13C6]glucose were pulse administered to a Gram-negative marine bacterium isolate. Phospholipid ester-linked fatty acids and β-hydroxybutyric acid showed extensive 13C-incorporation within 15 min after the pulse. After approximately 60 min a maximum of 10 atom% excess of 13C was reached for palmitoleic acid. The method provides the potential to measure the metabolic activity of bacterial communities by measuring the incorporation of 13C-labelled substrates into specific fatty acids that can be utilized as biomarkers for biomass, community structure and nutritional status.
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| 8. |
- Tunlid, Anders, et al.
(författare)
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Precision and sensitivity of the measurement of 15 N enrichment in D-alanine from bacterial cell walls using positive/negative ion mass spectrometry
- 1985
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Ingår i: Journal of Microbiological Methods. - 0167-7012. ; 3:3-4, s. 237-245
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Tidskriftsartikel (refereegranskat)abstract
- Sensitive detection of cellular components from specific groups of microbes can be utilized as 'signatures' in the examination of microbial consortia from soils, sediments or biofilms. Utilizing capillary gas chromatography/mass spectrometry and stereospecific derivatizing agents, D-alanine, a component localized in the prokaryotic (bacteria) cell wall, can be detected reproducibly. Enrichments of D- 15 N]alanine determined in E. coli grown with [ 15 N]ammonia can be determined with precision at 1.0 atom%. Chemical ionization with methane gas and the detection of negative ions (M-HF) - · and (M-F or M+H - HF) - formed from the heptafluorobutyryl D-2 butanol ester of D-alanine allowed as little as 8 pg (90 fmol) to be detected reproducibly. This method can be utilized to define the metabolic activity in terms of 15 N incorporation at the level of 10 3 -10 4 cells, as a function of the 15 N- 14 N ratio.
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| 9. |
- Danilov, Roman, et al.
(författare)
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Comparison of usefulness of three types of artificial substrata (glass, wood and plastic) when studying settlement patterns of periphyton in lakes of different trophic status
- 2001
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Ingår i: Journal of Microbiological Methods. - 0167-7012 .- 1872-8359. ; 45:3, s. 167-170
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Tidskriftsartikel (refereegranskat)abstract
- Usefulness of three types of artificial substrata (glass, wood and plastic) was tested when studying settlement patterns of periphyton in lakes of different trophic status. Strictly eu-, meso- and oligotrophic lakes in central Sweden were chosen as objects of the study. Glass slides, glass tubes, pieces of plastic (PVC) and pieces of wood of similar dimensions were placed for 9 weeks in July-August vertically 3 cm above bottom at a total depth of ca. 30 cm. Substrata were located at well-illuminated places without any other submerged objects (like macrophytes and stones), which could potentially affect colonisation patterns by algae. Periphyton communities, which colonised both the glass tubes and the pieces of wood tested, were specific enough to enable a clear classification of the lakes studied in eu-, meso- and oligotrophic. Glass tubes turned out to be the most favourable substratum when investigating settlement patterns of periphyton in this study. Although also colonised by periphytic species, wood did not support the same diversity and abundance of species as glass did. No algae were detected on the plastics studied. The plastics were covered entirely by a slime layer of bacteria. It is discussed if the nature of plastics could have some inhibitory effects on algal growth or the slime layer itself may have prevented settlement of algal spores.
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| 10. |
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