Cellular Fatty Acid Profiles Research Articles

Bacillus solisalsi sp. nov., a halotolerant, alkaliphilic bacterium isolated from soil around a salt lake

A novel Gram-positive, motile, rod-shaped bacterium isolated from a saline soil in China was characterized by a polyphasic taxonomic approach. The strain, designated YC1(T), was halotolerant [tolerating up to 15 % (w/v) NaCl] and alkaliphilic (growing at a broad pH range of 5-13). 16S rRNA gene sequence analysis revealed that the isolate belonged to the genus Bacillus, showing highest similarity to Bacillus macauensis JCM 13285(T) (98.0 %). However, DNA-DNA hybridization indicated low levels of genomic relatedness with B. macauensis JCM 13285(T) (8.5 %). The major isoprenoid quinone was MK-7 and the cellular fatty acid profile consisted of significant amounts of iso-C(15 : 0) (38.6 %) and anteiso-C(15 : 0) (35.9 %). The predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The G+C content of the genomic DNA was 41.8 mol%. On the basis of the polyphasic evidence from this study, strain YC1(T) (=KCTC 13181(T)=CGMCC 1.6854(T)) should be classified as the type strain of a novel species of the genus Bacillus, for which the name Bacillus solisalsi sp. nov. is proposed.

Proposal to transferFlavobacterium oceanosedimentum Carty and Litchfield 1978 to the genusCurtobacterium asCurtobacterium oceanosedimentumcomb. nov.

Flavobacterium oceanosedimentum Carty & Litchfield 1978(AL) had been described as a novel species in the genus Flavobacterium on the basis of phenotypic characteristics, although the organism shows a high G+C content, a property never found in the other members of the genus. In this study, we re-evaluated the taxonomic position of F. oceanosedimentum using a polyphasic approach. The 16S rRNA gene sequence of F. oceanosedimentum ATCC 31717(T) indicated that it is closely related to the genus Curtobacterium in the class Actinobacteria, showing 96.5-99.9% similarity values to Curtobacterium spp. Phylogenetic analysis based on the gene encoding the gyrase subunit B (gyrB) and DNA-DNA hybridization suggest that F. oceanosedimentum represents a separate species in the genus Curtobacterium, which is also supported by comparative analysis of cellular fatty acid profiles and a large array of phenotypic traits. We therefore propose to transfer F. oceanosedimentum to the genus Curtobacterium as Curtobacterium oceanosedimentum comb. nov.

Use of a rapid analytical method for identifying closely related Yersinia species to provide a procedure for food safety and security

Capillary gas chromatography with flame ionization detection (GC‐FID) analysis of chemical components of bacterial cells has provided useful information for rapid detection and identification of bacteria in clinical and diagnostic bacteriology laboratories and currently has increased significance for both food safety and security. GC‐FID was used to determine the cellular fatty acid (CFA) profiles of closely related Yersinia species. For GC‐FID analysis, whole cell fatty acid methyl esters (FAMEs) from cells cultured on brain heart infusion (BHI) agar at 35 (C for 24 h were obtained by saponification, methylation and extraction into hexane/methyl tert‐butyl ether. A data set for each Yersinia species was prepared using fatty acid profiles from five replicates prepared on different days. Major fatty acids of the 26 Yersinia strains evaluated in this study were straight‐chain 12:0, 14:0, 15:0, 16:0 and unsaturated 16:1 ω7c/16:1 ω6c, 18:1 ω7c, and 14:0 3OH/16:1 iso, and 17:0 ωcyclo 7‐8. The Yersinia species Y. enterocolitica, Y. pseudotuberculosis, Y. frederiksenii, Y. intermedii, Y. kristensenii, and Y. pestis have unique fatty acid patterns. The CFA profiles for Y. pestis and Y. pseudotuberculosis are similar, but there are several fatty acids, 16:1 ω5c, 16:0, 17:1 ω7c, 17:0 ωcyclo 7‐8, 19:0 and summed 18:2 ω6c, 9c/18:0 ante that differ significantly between these two species. Analysis of FAMEs from Yersinia strains grown on BHI agar by a rapid GC‐FID method can provide a sensitive procedure for the identification of these organisms, and this analytical method provides a procedure applicable to issues of both food safety and security.

Comparison of Yersinia pestis to other closely related Yersinia species using fatty acid profiles

Abstract Capillary gas chromatography with flame ionisation detection (GC–FID) was used to determine the cellular fatty acid (CFA) profiles of six Yersinia pestis strains. The profiles were then compared with the CFA profiles of other closely related Yersinia species including: Y. pseudotuberculosis, Y. enterocolitica, Y. intermedii, Y. kristensenii and Y. frederiksenii. For GC–FID analysis, whole cell fatty acid methyl esters (FAMEs) from cells cultured on brain–heart infusion (BHI) agar at 35 °C for 24 h were obtained by saponification, methylation and extraction into hexane/methyl tert-butyl ether. A data set for each Yersinia species was prepared using fatty acid profiles from five replicates prepared on different days. Major fatty acids of the 26 Yersinia strains evaluated in this study were straight-chain 12:0, 14:0, 15:0, 16:0 and unsaturated summed 16:1 ω7c/16:1 ω6c, 18:1 ω7c, and summed 14:0 3OH/16:1 iso, and 17:0 ω cyclo 7–8. The CFA profiles for Y. pestis and Y. pseudotuberculosis are similar, but there are several fatty acids, 16:1 ω5c, 16:0, 17:1 ω7c, 17:0 ω cyclo 7–8, 19:0 and summed 18:2 ω6c, 9c/18:0 ante, that differ significantly between these two species. Analysis of FAMEs from Yersinia strains grown on BHI agar by a rapid GC–FID method can provide a sensitive procedure for the identification of these organisms, and this analytical method provides a procedure for the differentiation of Y. pestis strains from closely related Yersinia species.

Bacteremia possibly caused by Curtobacterium spp found in a blood culture from a central venous line of a pediatric leukemia patient who underwent bone marrow transplantation

from humanclinical specimens in 2005.Curtobacteria are known plant pathogens that growbetter at 30 oC, and not the normal temperature of 35 oC that isused for growing blood culture isolates. Phenotyping iscomplex and based on cellular fatty acid profiles, a tool thatis not commonly available in clinical laboratories.

Chitiniphilus shinanonensis gen. nov., sp. nov., a novel chitin-degrading bacterium belonging to Betaproteobacteria

A bacterial strain capable of degrading chitin, strain SAY3T, was isolated from moat water of Ueda Castle in Nagano Prefecture, Japan. The strain was gram-negative, curved rod-shaped, facultatively anaerobic, and motile with a single polar flagellum. It grew well with chitin as a sole carbon source. The cellular fatty acids profiles showed the presence of C16:1 omega7c and C16:0 as the major components. The G+C content of DNA was 67.6 mol% and Q-8 was the major respiratory quinone. A 16S rRNA gene sequence-based phylogenetic analysis showed the strain belonged to the family Neisseriaceae but was distantly related (94% identity) to any previously known species. Since the strain was clearly distinct from closely related genera in phenotypic and chemotaxonomic characteristics, it should be classified under a new genus and a new species. We propose the name Chitiniphilus shinanonensis gen. nov., sp. nov. The type strain is SAY3T (=NBRC 104970T=NICMB 14509T).

Reclassification of Myxococcus flavescens Yamanaka et al. 1990VP as a later synonym of Myxococcus virescens Thaxter 1892AL

The taxonomic relatedness between the species Myxococcus flavescens and Myxococcus virescens was investigated. Literature data had already indicated the synonymy between the two species but this observation had not been formalized. Additional evidence that the two taxa represent a single species was provided by comparison of metabolic properties, cellular fatty acid profiles and from a DNA-DNA reassociation value of >80 %. Data from this study led to the proposal that M. flavescens should be reclassified as a later synonym of M. virescens.

Aliihoeflea aestuarii gen. nov., sp. nov., a novel bacterium isolated from tidal flat sediment

A novel Gram-negative and rod-shaped bacterium, designated N8(T), was isolated from tidal flat sediment. Phylogenetic analysis based on 16S rRNA gene sequences showed that N8(T) strain is associated with the family Phyllobacteriaceae: two uncultured clones (98.4 and 99.8% 16S rRNA gene sequence similarity) and the genus Mesorhizobium (< or =97.0%). The novel strain formed a separate clade with uncultured clones in the phylogenetic tree based on 16S rRNA gene sequences. Cellular fatty acid profiles predominately comprised C(18:1) omega7c and C(19:0) cyclo omega8c. The major isoprenoid quinone is ubiquinone-10 and genomic DNA G+C content is 53.4 mol%. The polyphasic taxonomic study indicates that the novel strain N8(T) represents a novel species of the new genus in the family Phyllobacteriaceae, named Aliihoeflea aestuarii. The type strain is N8(T) (= KCTC 22052(T)= JCM 15118(T)= DSM 19536(T)).

Cis-9,trans-11-conjugated linoleic acid but not its precursortrans-vaccenic acid attenuate inflammatory markers in the human colonic epithelial cell line Caco-2

Trans-vaccenic acid (TVA) is a natural trans fatty acid found in ruminant food produce. It is converted to the cis-9, trans-11 isomer of conjugated linoleic acid (c9, t11-CLA) by the action of stearoyl-CoA desaturase (SCD) in tissue. c9, t11-CLA has been associated with anti-inflammatory effects and also affects lipid metabolism. The aim of the present study was to determine if TVA is bioconverted to c9, t11-CLA in intestinal epithelial cells and to ascertain whether TVA has effects similar to c9, t11-CLA on markers of inflammation relevant to inflammatory bowel disease. The present study demonstrated that TVA treatment led to significant bioconversion into c9, t11-CLA in Caco-2 cells. Treatment with both TVA and c9, t11-CLA resulted in alteration of cellular fatty acid profile and SCD activity in the Caco-2 cell line. However, CLA, but not TVA, significantly modulated transcription of TNF-alpha, IL-12, IL-6 and production of IL-12 by these cells. Thus the present study established that TVA treatment can alter SCD desaturation indices and induce compositional changes in the fatty acid profile of the Caco-2 cell model of the human intestinal epithelium but this is not associated with functional effects on markers of the inflammatory response.

Analysis of survival rates and cellular fatty acid profiles of Listeria monocytogenes treated with supercritical carbon dioxide under the influence of cosolvents

In the present study, we identified several process variables that significantly affect the efficiency of supercritical carbon dioxide inactivation of the food-borne pathogen Listeria monocytogenes. Treatment with SC-CO 2 completely disabled the colony-forming activity of the cells (8-log reduction) within specific treatment time (10–50 min), pressure (80–150 bar), and temperature ranges (35–45 °C). Microorganism inactivation rates increased proportionally with pressure and temperature, but the inactivation rate decreased significantly when cells were suspended in phosphate-buffered saline rather than in physiological saline. Additionally, when the microbial cell suspension was 80–100% (w/w) of water, the SC-CO 2-mediated reduction in CFU ml − 1 was 4–8 log higher at the same treatment conditions than in typical cell suspensions (a water content of 800–4000% [w/w]) or dry preparations that had only 2–10% (w/w) of water. The addition of a fatty acid, oleic acid, decreased the effectiveness of the microbial inactivation by SC-CO 2, but the addition of a surfactant, sucrose monolaurate, increased the effectiveness. Therefore, cosolvents for SC-CO 2, including water, a fatty acid, and a surfactant in this study, were found to greatly influence on the inactivation effectiveness. The extraction of cellular substances, such as nucleic acid- and protein-like materials and fatty acids, was monitored by spectrophotometry and GC/MS and increased with SC-CO 2 treatment time. Additionally, using scanning and transmission electron microscopies, we investigated morphological changes in the SC-CO 2-treated cells. The effects of the variables we have described herein represent a significant contribution to our current knowledge of this method of inactivating food-borne pathogens.

Nocardioides dilutes sp. nov. Isolated from Soil in Bigeum Island, Korea

A short coccoid-rod-shaped, nonmotile actinobacteria strain MSL-11T was isolated from soil in Bigeum Island, Korea. A polyphasic study was undertaken to establish the taxonomic position of this strain. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain MSL-11T forms an evolutionary lineage within the radiation of the genus Nocardioides. The cell wall peptidoglycan of strain MSL-11T contained LL-diaminopimelic acid, indicating wall chemotype I. The predominant menaquinone was MK-8(H4). Strain MSL-11T had a cellular fatty acid profile containing straight-chain, branched, unsaturated, and 10-methyl fatty acids, with iso-C16:0 as a major fatty acid component detected. The DNA G + C content of the strain was 71.8 mol%. Comparative 16S rRNA gene sequencing revealed that the strains constituted a distinct subclade within the genus Nocardioides, displaying a 16S rRNA gene sequence similarity of about 95.68% with Nocardioides jensenii DSM 20641T. On the basis of both phenotypic and phylogenetic evidence, the strain is separated from previously described Nocardioides species and should be assigned to represent a novel species of the genus Nocardioides, for which the name Nocardioides dilutes sp. nov. is proposed. The type strain is strain MSL-11T (= KCTC 19288T = DSM 19318T).

Fatty acid analysis as a chemotaxonomic tool for taxonomic and epidemiological characterization of four fish pathogenic Tenacibaculum species

In this work, fatty acid content and profiles were analysed in order to differentiate the species Tenacibaculum maritimum, Tenacibaculum gallaicum, Tenacibaculum discolor and Tenacibaculum ovolyticum that are pathogenic for cultured marine fish and to assess the potential of fatty acid profiles as a tool for epizootiological typing. The fatty acid methylesters (FAMEs) were extracted from cells grown on marine agar for 48 h at 25 degrees C and were prepared and analysed according to the standard protocol of the MIDI/Hewlett Packard Microbial Identification System. The cellular fatty acid profiles of Tenacibaculum strains tested were characterized by the presence of large amounts of branched (36.1-40.2%) and hydroxylated (29.6-31.7%) fatty acids. The FAME products from the four species significantly (P < 0.05) differed in the content of iso-C(15:0)3-OH, iso-C(16:0)3-OH, iso-C(15:1)G, summed feature 3 (a component that contains C(16:1)omega7c and/or iso-C(15:0) 2-OH), iso-C(16:0), C(17:1)omega6c, C(15:0)3-OH, iso-C(17:0)3-OH. Results of present study demonstrated the existence of differences in the fatty acids content between the T. maritimum isolates from different marine fish/geographical origin and between strains of T. maritimum, T. discolor, T. gallaicum and T. ovolyticum. Profiling of fatty acids may be a useful tool to distinguish T. maritimum from other Tenacibaculum species pathogenic for fish as well as for epizootiological differentiation of T. maritimum isolates.

Bacillus butanolivorans sp. nov., a species with industrial application for the remediation of n-butanol

Four bacterial strains, designated K9(T), K105, K1012A and K101, were isolated from soil in Lithuania. All these strains could use n-butanol as a sole carbon source. The strains grew in a medium containing 12-120 mM n-butanol. The strains were strictly aerobic, Gram-positive endospore-formers. The best growth was achieved at 25 degrees C and pH 7.0 in medium containing 1 % (w/v) NaCl. The strains showed identical profiles of 16S-23S rRNA internal transcribed spacer PCR and nearly identical 16S rRNA gene PCR-RFLP electrophoretic patterns and physiological characteristics, demonstrating their relationship at the species level. The cellular fatty acid profile of K9(T) consisted of significant amounts of the C(15) branched-chain fatty acids iso-C(15 : 0) (16.78 %) and anteiso-C(15 : 0) (45.80 %). The diagnostic cell-wall diamino acid was meso-diaminopimelic acid. The 16S rRNA gene sequence of K9(T) showed the highest similarity to the sequences of Bacillus simplex DSM 1321(T) and Bacillus muralis LMG 20238(T) (98.3 and 97.7 %, respectively). The DNA G+C content was 37.4 mol%. Studies of DNA-DNA relatedness, morphological, physiological and chemotaxonomic analyses and phylogenetic data based on 16S rRNA gene sequencing allowed strains K9(T), K105, K1012A and K101 to be described as members of a novel species of the genus Bacillus, for which the name Bacillus butanolivorans sp. nov. is proposed. The type strain is K9(T) (=DSM 18926(T) =LMG 23974(T)).

Paracoccus marinus sp. nov., an adonixanthin diglucoside-producing bacterium isolated from coastal seawater in Tokyo Bay

Two novel marine, Gram-negative, non-motile, catalase- and oxidase-positive, aerobic bacteria were isolated from coastal seawater in Tokyo Bay. Analysis of almost-complete 16S rRNA gene sequences showed that the two isolates are members of the genus Paracoccus, sharing highest 16S rRNA gene sequence similarity (96.5 %) with Paracoccus aminophilus NBRC 16710(T). The DNA-DNA reassociation values between P. aminophilus NBRC 16710(T) and these isolates were only 10-20 %, in contrast to the high DNA relatedness between the two isolates (89 %). At least 1 % (w/v) NaCl was required for growth. Cellular fatty acid profiles revealed C(18 : 1)omega7c as the major component and C(10 : 0) 3-OH as the major hydroxy fatty acid. Ubiquinone-10 was detected as the major respiratory quinone. The G+C content of the genomic DNA of both strains was 69 mol%. On the basis of DNA-DNA hybridization data and physiological and chemotaxonomic characteristics, it is proposed that these strains should be placed in a novel species, Paracoccus marinus sp. nov. The type strain is KKL-A5(T) (=NBRC 100637(T) =CIP 108500(T)); KKL-B9 (=NBRC 100640) is a reference strain.

Methylobacterium iners sp. nov. and Methylobacterium aerolatum sp. nov., isolated from air samples in Korea

Two bacterial strains isolated from air samples, 5317S-33(T) and 5413S-11(T), were characterized by determining their phenotypic characteristics, cellular fatty acid profiles and phylogenetic positions based on 16S rRNA gene sequence analysis. 16S rRNA gene sequence analysis showed that these isolates belonged to the genus Methylobacterium. Strain 5317S-33(T) was most closely related to Methylobacterium adhaesivum AR27(T) (97.9% sequence similarity). Strain 5413S-11(T) was most closely related to Methylobacterium fujisawaense DSM 5686(T) (97.3% sequence similarity), Methylobacterium oryzae CBMB20(T) (97.1% similarity) and Methylobacterium radiotolerans JCM 2831(T) (97.0% similarity). Cells of both strains were strictly aerobic, Gram-negative, motile and rod-shaped. The major fatty acid was C(18:1)omega7c. The G+C contents of the genomic DNA were 68.0 mol% for strain 5317S-33(T) and 73.2 mol% for strain 5413S-11(T). According to DNA-DNA hybridization data, strain 5317S-33(T) showed a level of DNA-DNA relatedness of 33 % with M. adhaesivum DSM 17169(T), and strain 5413S-11(T) showed low levels of DNA-DNA relatedness (<35%) with M. fujisawaense DSM 5686(T), M. oryzae CBMB20(T) and M. radiotolerans DSM 1819(T). On the basis of this polyphasic analysis, it was concluded that strains 5317S-33(T) and 5413S-11(T) represent two novel species within the genus Methylobacterium, for which the names Methylobacterium iners sp. nov. (type strain 5317S-33(T) =KACC 11765(T) =DSM 19015(T)) and Methylobacterium aerolatum sp. nov. (type strain 5413S-11(T) =KACC 11766(T) =DSM 19013(T)) are proposed.

Bacillus polygoni sp. nov., a moderately halophilic, non-motile obligate alkaliphile isolated from indigo balls

A moderately halophilic, obligate alkaliphile (growth range pH 8-12), designated strain YN-1(T), was isolated from indigo balls obtained from Ibaraki, Japan. The cells of the isolate stained Gram-positive, and were aerobic, non-motile, sporulating rods which grew optimally at pH 9. The strain grew in 3-14% NaCl with optimum growth in 5% NaCl. It hydrolysed casein and Tweens 20, 40 and 60, but not gelatin, starch, DNA or pullulan. Its major isoprenoid quinone was MK-7 and its cellular fatty acid profile mainly consisted of anteiso-C(15:0), anteiso-C(17:0) and anteiso-C(17:1). 16S rRNA phylogeny suggested that strain YN-1(T) was a member of group 7 (alkaliphiles) of the genus Bacillus, with the closest relative being Bacillus clarkii DSM 8720(T) (similarity 99.5%). However, DNA-DNA hybridization showed a low DNA-DNA relatedness (7%) of strain YN-1(T) with B. clarkii DSM 8720(T). Owing to the significant differences in phenotypic and chemotaxonomic characteristics, and phylogenetic and DNA-DNA relatedness data, the isolate merits classification as a new species, for which the name Bacillus polygoni is proposed. The type strain of this species is YN-1(T) (=JCM 14604(T)=NCIMB 14282(T)).

Methylophaga aminisulfidivorans sp. nov., a restricted facultatively methylotrophic marine bacterium

A novel restricted facultatively methylotrophic marine strain, MP(T), possessing the ribulose monophosphate pathway of C(1)-carbon compound assimilation was isolated from a seawater sample obtained from Mokpo, South Korea. The novel isolate is aerobic, Gram-negative, asporogenous and a non-motile short rod. It grows well on methanol, methylated amines, dimethylsulfide and DMSO. Optimal growth occurs with 3 % NaCl at 30 degrees C and pH 7.0. Fructose is utilized as a multicarbon source. Growth factors are not required and vitamin B(12) does not stimulate growth. The cellular fatty acid profile of the novel strain consists primarily of straight-chain saturated C(16 : 0) and unsaturated C(16 : 1) acids. The major ubiquinone is Q-8. The dominant phospholipids are phosphatidylethanolamine and phosphatidylglycerol. The DNA G+C content is 44.9 mol% (T(m)). Based on 16S rRNA gene sequence analysis and DNA-DNA relatedness (25-41 %) with the type strains of marine methylotrophs belonging to the genus Methylophaga, it is suggested that isolate MP(T) represents a novel species, Methylophaga aminisulfidivorans sp. nov. (type strain MP(T)=KCTC 12909(T)=VKM B-2441(T)=JCM 14647(T)).

Prevotella pleuritidis sp. nov., isolated from pleural fluid

A strain isolated from pleural fluid of a patient with suppurative pleuritis (strain GTC 3021(T)) was characterized in terms of its phenotypic and biochemical features, cellular fatty acid profile and phylogenetic position based on 16S rRNA gene sequence analysis. 16S rRNA gene sequence analysis showed that the isolate was a member of the genus Prevotella. The isolate was related to Prevotella enoeca ATCC 51261(T) with about 92 % 16S rRNA gene sequence similarity. The strain was an obligately anaerobic, non-pigmenting, non-spore-forming, non-motile, Gram-negative rod. Although the phenotypic and biochemical characteristics of the strain were similar to those of P. enoeca JCM 12259(T), the cellular fatty acid composition of the isolate was significantly different from that of P. enoeca JCM 12259(T) (C(18 : 1) omega 9c and anteiso-C(15 : 0) fatty acid content). Based on these data, we propose a novel Prevotella species, Prevotella pleuritidis sp. nov., with the type strain GTC 3021(T) (=JCM 14110(T) =CCUG 54350(T)). The G+C content of the type strain is 45.4 mol%.

Aquincola tertiaricarbonis gen. nov., sp. nov., a tertiary butyl moiety-degrading bacterium

Strains L10(T), L108 and CIP I-2052 were originally obtained from methyl tert-butyl ether (MTBE)-contaminated groundwater and from a wastewater treatment plant, respectively. All share the ability to grow on tert-butanol, an intermediate of MTBE degradation. Cells are strictly aerobic, motile by a polar flagellum and exhibit strong pili formation. Poly beta-hydroxybutyrate (PHB) granules are formed. The DNA G+C content is 69-70.5 mol% and the main ubiquinone is Q-8. The major cellular fatty acids are 16 : 1 cis-9 and 16 : 0 and the only hydroxy fatty acid is 10 : 0 3-OH. The major phospholipids are phosphatidylethanolamine (PE) 16 : 1/16 : 1 and phosphatidylglycerol 16 : 0/16 : 1. A significant amount of PE 17 : 0/16 : 1 is present. The 16S rRNA gene sequences of these strains are almost identical and form a separate line of descent in the Rubrivivax-Roseateles-Leptothrix-Ideonella-Aquabacterium branch of the Betaproteobacteria with 97 % similarity to 16S rRNA genes of the type strains of Rubrivivax gelatinosus, Leptothrix mobilis and Ideonella dechloratans. However, physiological properties, DNA-DNA relatedness values and the phospholipid and cellular fatty acid profiles distinguish the novel isolates from the three closely related genera. Therefore, it is concluded that strains L10(T), L108 and CIP I-2052 represent a new genus and novel species for which the name Aquincola tertiaricarbonis gen. nov., sp. nov., is proposed. The type strain is strain L10(T) (=DSM 18512(T)=CIP 109243(T)).

Differentiation of Enterobacter sakazakii from Closely Related Enterobacter and Citrobacter Species Using Fatty Acid Profiles

Capillary gas chromatography with flame ionization detection (GC-FID) was used to determine the cellular fatty acid (CFA) profiles of 134 Enterobacter sakazakii strains, and these were compared to the CFA profiles of other closely related Enterobacter and Citrobacter species. For GC-FID analysis, whole cell fatty acid methyl esters (FAMEs) from cells cultured on brain heart infusion (BHI) agar at 37 degrees C for 24 h were obtained by saponification, methylation, and extraction into hexane/methyl tert-butyl ether. A database for E. sakazakii was prepared using fatty acid profiles from the 134 strains. Major fatty acids of E. sakazakii strains evaluated in this study were straight-chain 12:0, 14:0, and 16:0, unsaturated 18:1 omega7c, and 17:0 omegacyclo 7-8. Principal component analysis (PCA) based on CFA profiles for E. sakazakii strains shows separation of E. sakazakii subgroups A and B. The CFA profiles for E. sakazakii and Enterobacter cloacae show that there are several fatty acids, 14:0, 17:0 omegacyclo 7-8, 18:1 omega7c, and summed 16:1 omega6c/16:1 omega7c, that differ significantly between these two species. A PCA model based on CFA profiles for E. sakazakii strains clearly shows separation of E. sakazakii from closely related Enterobacter and Citrobacter species. Analysis of FAMEs from E. sakazakii strains grown on BHI agar by a rapid GC-FID method can provide a sensitive procedure for the identification of this organism, and this analytical method provides a confirmatory procedure for the differentiation of E. sakazakii strains from closely related Enterobacter and Citrobacter species.