Analysis Of Bacterial Fatty Acids Research Articles

Analysis of bacterial fatty acids by flow modulated comprehensive two-dimensional gas chromatography with parallel flame ionization detector/mass spectrometry

Comprehensive two-dimensional gas chromatography (GC × GC) offers an interesting tool for profiling bacterial fatty acids. Flow modulated GC × GC using a commercially available system was evaluated, different parameters such as column flows and modulation time were optimized. The method was tested on bacterial fatty acid methyl esters (BAMEs) from Stenotrophomonas maltophilia LMG 958 T by using parallel flame ionization detector (FID)/mass spectrometry (MS). The results are compared to data obtained using a thermal modulated GC × GC system. The data show that flow modulated GC × GC-FID/MS method can be applied in a routine environment and offers interesting perspectives for chemotaxonomy of bacteria.

GC–MS–MS analysis of bacterial fatty acids in heavily creosote-contaminated soil samples

Phospholipid fatty acid profiles of soil samples enable rapid and reproducible measurement and characterization of the dominant soil microbial communities. When extensive polycyclic aromatic hydrocarbon (PAH) pollution is present in the soil it is very difficult, or even impossible, to distinguish specific fatty acids in GC-MS chromatograms in full-scan mode, because of the PAHs which, because of their lipophilic character, are co-extracted with the lipids. Selected ions in the samples were scanned in MS-MS mode to eliminate the aromatic hydrocarbon signals and obtain clear chromatograms of the fatty acids. By using this technique it was possible to clearly distinguish at least eleven fatty acids in heavily creosote-contaminated soil samples (PAH concentration approximately 15 g kg(-1) dry weight of soil).

Genetic Diversity of Xanthomonas campestris pv. vitians, the Causal Agent of Bacterial Leafspot of Lettuce

ABSTRACT Bacterial leafspot of lettuce (BLS), caused by Xanthomonas campes-tris pv. vitians, has become more prevalent in many lettuce-growing areas of the world over the past decade. To gain insight into the nature of these outbreaks, the genetic variation in X. campestris pv. vitians strains from different geographical locations was examined. All strains were first tested for pathogenicity on lettuce plants, and then genetic diversity was assessed using (i) gas-chromatographic analysis of bacterial fatty acids, (ii) polymerase chain reaction analysis of repetitive DNA sequences (rep-PCR), (iii) DNA sequence analysis of the internal transcribed spacer region 1 (ITS1) of the ribosomal RNA, (iv) restriction fragment length polymorphism (RFLP) analysis of total genomic DNA with a repetitive DNA probe, and (v) detection and partial characterization of plasmid DNA. Fatty acid analysis identified all pathogenic strains as X. campestris, but did not consistently identify all the strains as X. campestris pv. vitians. The rep-PCR fingerprints and ITS1 sequences of all pathogenic X. campestris pv. vitians strains examined were identical, and distinct from those of the other X. campestris pathovars. Thus, these characteristics did not reveal genetic diversity among X. campestris pv. vitians strains, but did allow for differentiation of X. campestris pathovars. Genetic diversity among X. campestris pv. vitians strains was revealed by RFLP analysis with a repetitive DNA probe and by characterization of plasmid DNA. This diversity was greatest among strains from different geographical regions, although diversity among strains from the same location also was detected. The results of this study suggest that these X. campestris pv. vitians strains are not clonal, but comprise a relatively homogeneous group.

Changes in fatty acids of Pseudomonas nautica, a marine denitrifying bacterium, in response to n-eicosane as carbon source and various culture conditions

This study determined the effects of shifts in environmental conditions on the fatty acid composition of a sedimentary facultative anaerobic denitrifying marine bacteria (Pseudomonas nautica strain IP 617). The effects of carbon source (n-eicosane, sodium acetate and rich medium), temperature (13, 20 and 30°C), presence or lack of oxygen and growth phase (stationary and exponential) were investigated. As demonstrated by correspondence analysis, the effect of the various conditions tested, in descending order of importance, were carbon source>temperature>growth phase≥oxygen. Among the different growth substrates, n-eicosane (nC20) led to the most distinct FA profiles, characterised by high amounts of saturated and branched FA, the appearance of 20-carbon acids (20:1ω9 and 20:0) and a Δ10 methyl branched series with mainly the 10Me16:0. With regard to temperature effects, P. nautica showed a mean acyl chain length thermoregulation process for the major monounsaturated fatty acids which led to increased values of the ratio ΣC18:1/ΣC16:1 with increasing temperatures. The effect of growth phase and anaerobiosis were less marked. The analysis of bacterial fatty acids could enable the detection of hydrocarbonoclastic bacterial communities in marine sediments contaminated by hydrocarbons.

Changes in fatty acids of Pseudomonas nautica, a marine denitrifying bacterium, in response to n-eicosane as carbon source and various culture conditions

This study determined the effects of shifts in environmental conditions on the fatty acid composition of a sedimentary facultative anaerobic denitrifying marine bacteria ( Pseudomonas nautica strain IP 617). The effects of carbon source ( n-eicosane, sodium acetate and rich medium), temperature (13, 20 and 30°C), presence or lack of oxygen and growth phase (stationary and exponential) were investigated. As demonstrated by correspondence analysis, the effect of the various conditions tested, in descending order of importance, were carbon source>temperature>growth phase≥oxygen. Among the different growth substrates, n-eicosane ( nC 20) led to the most distinct FA profiles, characterised by high amounts of saturated and branched FA, the appearance of 20-carbon acids (20:1ω9 and 20:0) and a Δ 10 methyl branched series with mainly the 10Me16:0. With regard to temperature effects, P. nautica showed a mean acyl chain length thermoregulation process for the major monounsaturated fatty acids which led to increased values of the ratio ΣC 18:1/ΣC 16:1 with increasing temperatures. The effect of growth phase and anaerobiosis were less marked. The analysis of bacterial fatty acids could enable the detection of hydrocarbonoclastic bacterial communities in marine sediments contaminated by hydrocarbons.

Ecotypic Specificity of Spruce Emergence-Stimulating Pseudomonas putida

Abstract Hybrid spruce (Picea glauca X engelmannii) seed and seedlings were collected from two sites in British Columbia, near Mackenzie and near Salmon Arm. One strain of Pseudomonas putida was isolated from the rhizosphere of seedlings collected from each site. These strains were deduced to be distinct from each other based on analysis of bacterial fatty acids. Experiments were conducted to determine if P. putida affected spruce seedling emergence, and if the nature or magnitude of these effects were related to the geographic origin of bacteria and seed. Inoculation of spruce with P. putida that did not originate from the same site as the seed caused an increase in the number of seedlings that emerged, but this effect was not statistically significant. However, when the origin of the spruce seed was matched to that of the P. putida strain, a significant (P < 0.05) increase in the amount and rate of seedling emergence was detected. These results are discussed in relation to the regeneration strategy of spruce in natural forests. For. Sci. 39(3):520-527.

Direct analysis of bacterial fatty acids by Curie-point pyrolysis tandem mass spectrometry

Although pyrolysis-mass spectrometry (Py-MS) has been used for bacterial taxonomy, many of the mass spectral peaks used for discrimination of organisms have not been correlated to known biomolecules. This work presents the discrimination of five bacterial species based on Py-MS patterns containing only peaks that can be correlated to fatty acids and fatty acid derivatives. These correlations were confirmed by pyrolysis-tandem mass spectrometry of authentic standards and the organisms. The pattern recognition procedures used gave better results when only the fatty acid peaks were used in the analysis than when full spectra were used.

Injection principles in capillary gas chromatographic analysis of bacterial fatty acids

Principles for sample injection in fused silica capillary gas chromatographic analysis of bacterial cellular fatty acids are discussed. Comparative analyses were made of the methyl esters of fatty acids in a reference solution and in Legionella pneumophila serogroup 1, using both split and splitless injection. A splitless injection technique, in which the methyl esters are cold-trapped immediately after injection and consecutively released in accordance with temperature programming, gave sensitivity increase corresponding to the split ratio used in split injections, without diminishing the speed of analysis or separation efficiency. Splitless injection, utilizing cold-trapping, can be recommended for capillary gas chromatography in routine profiling of bacterial fatty acids.

Gas-liquid chromatography of bacterial fatty acids with a fused-silica capillary column.

The use of flexible, fused-silica capillary column for gas-liquid chromatographic analysis of bacterial fatty acids is illustrated with Propionibacterium acnes, Propionibacterium shermanii, and a standard methyl ester mixture.

Comparison of Rapid Methods for Analysis of Bacterial Fatty Acids

When rapid gas-liquid chromatography methods for determination of bacterial fatty acids were compared, results showed that saponification was required for total fatty acid analysis. Transesterification with boron-trihalide reagents (BF(3)-CH(3)OH, BCl(3)-CH(3)OH) caused extensive degradation of cyclopropane acids and was less effective than saponification in releasing cellular hydroxy fatty acids. Digestion of cells with tetramethylammonium hydroxide was unsatisfactory because of extraneous gas-liquid chromatography peaks and because of lower recovery of branched-chain and hydroxy fatty acids. A simple, rapid saponification procedure which can be used for total cellular fatty acid analysis of freshly grown cells is described.