Temporal evolution of fatty acid content in human milk of lactating mothers from the Philippines.

Fatty acids (FA) play a key role in infant growth and development. The aim of this study was to study the temporal evolution of FA from 3 or 4 weeks to 4 months postpartum in human milk (HM) from Filipino mothers. Mid-morning HM samples (n = 41) were collected after full expression from a single breast and FA were assessed using gas-liquid chromatography coupled to flame ionization detector. The total FA content remained relatively constant over the study period. The most abundant FA in HM were oleic acid (OA), palmitic acid (PA) and linoleic acid (LA), a trend similarly reported in HM from European and Chinese mothers. The former two were unchanged over the course of lactation while there was a slight increase in LA content over time. Similarly, the saturated fatty acid (SFA) and monounsaturated FA (MUFA) contents did not vary over the first four months of lactation. The SFA content was much higher than that reported in HM from Europe and China, mainly driven by PA, lauric and myristic acids. The MUFA content on the other hand, while comparable to that reported in HM from Chinese populations was lower than that reported in Europe. There was a small increase in the polyunsaturated FA (PUFA) content over the study duration. The levels of essential FA, linoleic acid (LA) and α-linolenic acid (ALA) were found to be much lower than that reported in other populations. The concentrations of arachidonic acid (AA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) remained stable over the study duration. AA and DHA in HM from Filipino mothers were comparable to global averages, however in case of the latter the concentration was found to be lower than in previous reports. DHA is of great clinical significance as it plays a key role in infant growth and development. In our study, we observed a wide inter- and intra-individual variability in the levels of DHA in HM, presumably reflecting diverse intakes of DHA rich foods and bioconversion in vivo. Personalized recommendations may help achieve recommended levels of DHA amongst population with levels below global averages. This may help achieve HM sufficiency and therefore be linked to clinical benefits for the mother and the baby. SUMMARY: This study details the temporal evolution of human milk (HM) fatty acids (FA) in Filipino mothers up to four months postpartum. The total FA content remained relatively constant over the study period. The most abundant FA were oleic, palmitic and linoleic acids. HM from Filipino mothers had relatively higher saturated FA content driven by palmitic, lauric and myristic acids, while the levels of essential FA, linoleic and α-linoleic acids were lower compared to other populations. Similarly, the concentration of monounsaturated FA were also lower than that reported in HM from European mothers. Arachidonic acid and docosahexaenoic acid (DHA) concentrations were comparable to global averages however the HM DHA levels were seen to have decreased when compared to previous reports from the Philippines. Additionally, a wide variability was seen in HM DHA levels suggesting a need for strategies such as personalized recommendations in order to ensure HM DHA sufficiency.

Multi-omics analyses reveal that the gut microbiome and its metabolites promote milk fat synthesis in Zhongdian yak cows.

Background: Yak cows produce higher quality milk with higher concentrations of milk fat than dairy cows. Recently, studies have found the yak milk yield and milk fat percentage have decreased significantly over the past decade, highlighting the urgency for yak milk improvement. Therefore, we aimed to analyze how the gut microbiome impacts milk fat synthesis in Zhongdian yak cows. Methods: We collected milk samples from Zhongdian yak cows and analyzed the milk fat percentage, selecting five Zhongdian yak cows with a very high milk fat percentage (>7%, 8.70 ± 1.89%, H group) and five Zhongdian yak cows with a very low milk fat percentage (<5%, 4.12 ± 0.43%, L group), and then obtained gut samples of these ten Zhongdian yak cows through rectal palpation. Gut metagenomics, metabolomics, and conjoint metagenomics and metabolomics analyses were performed on these samples, identifying taxonomic changes, functional changes, and changes in gut microbes-metabolite interactions within the milk fat synthesis-associated Zhongdian yak cows gut microbiome, to identify potential regulatory mechanisms of milk fat at the gut microbiome level in Zhongdian yak cows. Results: The metagenomics analysis revealed Firmicutes and Proteobacteria were significantly more abundant in the gut of the high-milk fat Zhongdian yak cows. These bacteria are involved in the biosynthesis of unsaturated fatty acids and amino acids, leading to greater efficiency in converting energy to milk fat. The metabolomics analysis showed that the elevated gut metabolites in high milk fat percentage Zhongdian yak cows were mainly enriched in lipid and amino acid metabolism. Using a combined metagenomic and metabolomics analysis, positive correlations between Firmicutes (Desulfocucumis, Anaerotignum, Dolosiccus) and myristic acid, and Proteobacteria (Catenovulum, Comamonas, Rubrivivax, Marivita, Succinimouas) and choline were found in the gut of Zhongdian yak cows. These interactions may be the main contributors to methanogen inhibition, producing less methane leading to higher-efficient milk fat production. Conclusions: A study of the gut microbe, gut metabolites, and milk fat percentage of Zhongdian yak cows revealed that the variations in milk fat percentage between yak cows may be caused by the gut microbes and their metabolites, especially Firmicutes-myristic acid and Proteobacteria-choline interactions, which are important to milk fat synthesis. Our study provides new insights into the functional roles of the gut microbiome in producing small molecule metabolites and contributing to milk performance traits in yak cows.

Profiling of 3-hydroxy fatty acids as environmental markers of endotoxin using liquid chromatography coupled to tandem mass spectrometry.

3-Hydroxy acids are constituents of the lipid A part of lipopolysaccharides and may potentially be used as chemical markers of endotoxin. While commercial enzymatic assays, such as the widely used Limulus amebocyte lysate (LAL) assay, commonly detect merely the water-soluble fraction of the bioactive endotoxin, the chemical approach aims to estimate the total amount of endotoxin present in a sample. Our objective was to develop a simple method for quantitative profiling of 3-hydroxy fatty acids in occupational and environmental samples based on detection with HPLC-MS/MS. We included eleven 3-hydroxy fatty acids (3-hydroxyoctanoic acid to 3-hydroxyoctadecanoic acid) in the HPLC-MS/MS based method, which involved base hydrolysis of filter samples using 1M sodium hydroxide and removal of the base as well as concentration of the fatty acids using solid-phase extraction on a functionalized polystyrene-divinylbenzene polymer. Recovery trials from spiked glass fiber filters, using threo-9,10-dihydroxyhexadecanoic acid as internal standard, gave an overall recovery of 54-86% for 3-hydroxy fatty acids of medium chain length (3-hydroxynonanoic to 3-hydroxypentadecanoic acid). 3-Hydroxyoctanoic acid and the longer chain fatty acids were more problematic yielding overall spike recoveries of 11-39%. While the 3-hydroxy fatty acid profile of pure lipopolysaccharides was dominated by 3-hydroxydecanoic, 3-hydroxydodecanoic and 3-hydroxytetradecanoic acid the aqueous phase from drilling mud contained in addition relatively high amounts of 3-hydroxyoctanoic and 3-hydroxynonanoic acid. Endotoxin activity as measured by the LAL assay was reasonably correlated (R(2)=0.54) to the sum of 3-hydroxydecanoic acid, 3-hydroxydodecanoic acid and 3-hydroxytetradecanoic acid in these samples.

Β-hydroxymyristic acid as a chemical marker to detect endotoxins in dialysis water.

An analytical chemical method has been developed for determination of ß-hydroxymyristic acid (ß-HMA), a component of lipopolysaccharides (LPSs/endotoxins) in dialysis water. In our investigation, the ß-HMA component was used as a chemical marker for endotoxin presence in dialysis water because it is available in the molecular subunit (lipid A) and responsible for toxicity. It is the most abundant saturated fatty acid in that subunit. The developed method is based on fluorescence derivatization with 4-nitro-7-piperazino-2,1,3-benzoxadiazole (NBD-PZ). A high-performance liquid chromatographic separation of the ß-HMA derivative was achieved using an octadecyl silica column in gradient elution. A wide dynamic range of ß-HMA was tested and a calibration curve was constructed with accuracy of 90% and variability of less than 10%. The limits of detection and quantification obtained were 2 and 5µM, respectively. The developed method was applied to detect endotoxins in dialysis water by alkaline hydrolysis of LPS using NaOH (0.25M) at 60°C for 2h. After hydrolysis, free acid was detected as its NBD-PZ derivative using high-performance liquid chromatography/mass spectrometry (HPLC/MS). Good recovery rates ranging from 98 to 105% were obtained for ß-HMA in dialysis water.

[Determination of undecanoic acid and 13-methyl-tetradecanoic acid connected to the glyceride with internal standard method and its application to the identification of adulteration of illegal cooking oil].

On the basis of the source of illegal cooking oil (heated vegetable oil and animal oil) and the important referents reflecting their sources, namely, undecanoic acid and 13-methyl-tetradecanoic acid connected to the glyceride, their corresponding ramifications in edible oil were detected with internal standard method. The sensitivity and selectivity of this method were improved by the on-line cleanup and preconcentration. The detection limits of the method were 0.070 mg/kg for undecanoic acid and 0.006 mg/kg for 13-methyl-tetradecanoic acid. Additionally, most of the normal vegetable oils have lower levels of both fatty acids than illegal cooking oils. It was suggested to evaluate the quality of edible oils to some extent on the basis of the contents of undecanoic acid and 13-methyl-tetradecanoic acid.

Sphingobium limneticum sp. nov. and Sphingobium boeckii sp. nov., two freshwater planktonic members of the family Sphingomonadaceae, and reclassification of Sphingomonas suberifaciens as Sphingobium suberifaciens comb. nov.

Two novel chemo-organoheterotrophic members of the Sphingomonadaceae were isolated from alpine and pre-alpine lakes. Cells stained gram-negative, were motile and rod-shaped, and formed yellow, circular, convex colonies on different agar media. Strains 301(T) and 469(T) were strictly aerobic, catalase- and oxidase-positive, and grew at temperatures between 10 and 40 °C (optimum, 28 °C), and at pH values between 5 and 10 (optimum, pH 7). Both strains contained Q-10 as the dominant quinone, sphingoglycolipids and 2-hydroxymyristic acid, whereas 3-hydroxy fatty acids were absent. Major fatty acids of strain 301(T) were C(18 : 1)ω7c (53.3 %) and C(16 : 1)ω7c (22.9 %), with C(14 : 0) 2-OH (10.8 %) as the major 2-hydroxy fatty acid. Fatty acids of strain 469(T) were dominated by C(18 : 1)ω7c (34.4 %), C(16 : 1)ω7c (32.0 %) and C(14 : 0) 2-OH (15.2 %) as the major 2-hydroxy fatty acid. The genomic DNA G+C contents of strains 301(T) and 469(T) were 63.4 and 64.6 mol%, respectively. 16S rRNA gene sequence comparison indicated that both strains belonged to the genus Sphingobium. This classification was supported by the presence of spermidine as the major polyamine. The phylogenetically closest relatives of strain 301(T) were Sphingobium amiense DSM 16289(T), Sphingobium vermicomposti DSM 21299(T), Sphingobium yanoikuyae DSM 7462(T) and Sphingobium scionense DSM 19371(T) (98.8, 98.0, 97.9 and 97.4 % sequence similarity, respectively). DNA-DNA hybridization of genomic DNA yielded similarities in the range 43.2-12.1 % between strain 301(T) and the type strains of these four Sphingobium species. Closest relatives of strain 469(T) were Sphingomonas suberifaciens DSM 7465(T) and Sphingobium scionense DSM 19371(T) (97.1 and 96.5 % 16S rRNA gene sequence similarity, respectively). The degree of DNA-DNA hybridization between strain 469(T) and Sphingomonas suberifaciens DSM 7465(T) was 17.9 %. Based on the results of the molecular analyses and their phenotypic characteristics, strains 301(T) and 469(T) represent two novel species of the genus Sphingobium. The name Sphingobium limneticum sp. nov. is proposed for strain 301(T)( = DSM25076(T) = LMG 26659(T)). The name Sphingobium boeckii sp. nov. is proposed for strain 469(T) ( = DSM 25079(T) = LMG 26901(T)). The polyphasic analysis also suggests that Sphingomonas suberifaciens should be reclassified as Sphingobium suberifaciens comb. nov. with Ca1(T) ( = EY 2404(T) = ATCC 49355(T) = CIP 105429(T) = DSM 7465(T) = ICMP 12535(T) = NBRC 15211(T) = JCM 8521(T) = LMG 17323(T) = NCPPB 3629(T)) as the type strain.

[Biological activity of Budvicia aquatica lipopolysaccharides].

The fatty acid composition of lipopolysaccharides (LPS) lipids A of Budvicia aquatica strains (n = 6)--representatives of Enterobacteriaceae new species are studied for the first time. It was established that fatty acids with the length of carbon chains from C12 to C18 are presented. All of B. aquatica strains tested have been found to contain 3-hydroxytetradecanoic acid (23.1-43.8%, depending on the strain), which was predominat and characteristic of representatives of Enterobacteriaceae family. LPS of the tested strains displayed toxicity and pyrogeneity.

Polymers from fatty acids: poly(ω-hydroxyl tetradecanoic acid) synthesis and physico-mechanical studies.

This Article describes the synthesis and physicomechanical properties of bioplastics prepared from methyl ω-hydroxytetradecanoic acid (Me-ω-OHC14), a new monomer available by a fermentation process using an engineered Candida tropicalis strain. Melt-condensation experiments were conducted using titanium tetraisopropoxide (Ti[OiPr](4)) as a catalyst in a two-stage polymerization (2 h at 200 °C under N(2), 4 h at 220 °C under 0.1 mmHg). Poly(ω-hydroxytetradecanoate), P(ω-OHC14), M(w), determined by SEC-MALLS, increased from 53K to 110K as the Ti(OiPr)(4) concentration increased from 50 to 300 ppm. By varying the polymerization conditions (catalyst concentration, reaction time, second-stage reaction temperature) a series of P(ω-OHC14) samples were prepared with M(w) values from 53K to 140K. The synthesized polyesters with M(w) ranging from 53K to 140K were subjected to characterization by DSC, TGA, DMTA, and tensile testing. Influences of P(ω-OHC14) molecular weight, melting point, and enthalpies of melting/crystallization on material tensile properties were explored. Cold-drawing tensile tests at room temperature for P(ω-OHC14) with M(w) 53K-78K showed a brittle-to-ductile transition. In contrast, P(ω-OHC14) with M(w) 53K undergoes brittle fracture. Increasing P(ω-OHC14) M(w) above 78K resulted in a strain-hardening phenomena and tough properties with elongation at break ~700% and true tensile strength of ~50 MPa. Comparisons between high density polyethylene and P(ω-OHC14) mechanical and thermal properties as a function of their respective molecular weights are discussed.

Production and characterization of medium-chain-length polyhydroxyalkanoate with high 3-hydroxytetradecanoate monomer content by fadB and fadA knockout mutant of Pseudomonas putida KT2442.

Medium-chain-length polyhydroxyalkanoates (mcl-PHA) consisting of 3-hydroxyhexanoate (HHx), 3-hydroxyoctanoate (HO), 3-hydroxydecanoate, 3-hydroxydodecanoate, and high-content 3-hydroxytetradecanoate (HTD) was produced by knockout mutant Pseudomonas putida KT2442 termed P. putida KTOY06. When grown on 6 to14 g/L single-carbon-source tetradecanoic acid, P. putida KTOY06, which beta-oxidation pathway was weakened by deleting genes of 3-ketoacyl-coenzyme A (CoA) thiolase (fadA) and 3-hydroxyacyl-CoA dehydrogenase (fadB), for the first time, produced several mcl-PHA including 31 to 49 mol% HTD as a major monomer. HHx contents in these mcl-PHAs remained approximately constant at less than 3 mol%. In addition, large amounts of oligo-HTD were detected in cells, indicating the limited ability of P. putida KTOY06 in polymerizing long-chain-length 3-hydroxyalkanoates. The mcl-PHA containing high HTD monomer contents was found to have both higher crystallinity and improved tensile strength compared with that of typical mcl-PHA.

Structural features of lipid A of Piscirickettsia salmonis, the etiological agent of the salmonid rickettsial septicemia.

The composition and structure of lipid A isolated from the lipopolysaccharide (LPS) of Piscirickettsia salmonis were investigated by chemical analyses, gas chromatography/mass spectrometry (GCMS), and electrospray ionization (ESI) combined with the tandem mass spectrometry (MS/MS). Our study revealed moderate compositional and structural heterogeneity of lipid A with respect to the content of phosphate groups and 4-amino-4-deoxy-L-arabinopyranose (Ara4N) residues and with regard to the degree of acylation. It appeared that at least two molecular species were present in lipid A. The major species represented the hexaacyl lipid A consisting of the ss-(1--> 6)-linked D-glucosamine (GlcN) disaccharide backbone carrying two phosphate groups. The first one at the glycosidic hydroxyl group of the reducing GlcN I and the second one at the O-4' position of the non-reducing GlcN II. The primary fatty acids consisted of three 3-hydroxytetradecanoic [C14:0(3-OH)] and one 3-hydroxyhexadecanoic [C16:0(3-OH)] acids. The latter was amide-linked to GlcN I and one C14:0(3-OH) was amide-linked to GlcN II. Two secondary fatty acids were represented by C14:0(3-OH) and were equally distributed between the O-2' and O-3' positions. The phosphate group at O-4' carried a non-stoichiometric substituent Ara4N. The minor lipid A species contained exclusively C14:0(3-OH) with an asymmetric distribution (4+2) at GlcN II and GlcN I, respectively. The P. salmonis lipid A resembles structurally strongly endotoxic enterobacterial lipid A. This could be one of the reasons for the observed high endotoxicity of P. salmonis.

Impact on lipid membrane organization by free branched-chain fatty acids.

Here, we exploit the non-invasive techniques of solid-state NMR (nuclear magnetic resonance) and differential scanning calorimetry (DSC) to study the effect of free iso and ante-iso branched chain fatty acids (BCFAs) on the physicochemical properties of lipid membranes. Free fatty acids are present in biological membranes at low abundance, but can influence the cellular function by modulating the membrane organization. Solid state NMR spectra of dimyristoylphosphatidylcholine (DMPC) lipid membranes containing either free 12-methyltetradecanoic acid (a15:0) or free 13-methyltetradecanoic acid (i15:0), show significant differences in their impact on the lipid bilayer. Chain order profiles obtained by deuterium NMR on fully deuterated DMPC-d(67) bilayers revealed an ordering effect induced by both fatty acids on the hydrophobic membrane core. This behavior was also visible in the corresponding DSC thermograms where the main phase transition of DMPC bilayers-indicative of the hydrophobic membrane region-was shifted to higher temperatures, with the iso isomer triggering more pronounced changes as compared to the ante-iso isomer. This is probably due to a higher packing density in the core of the lipid bilayer, which causes reduced diffusion across membranes. By utilizing the naturally occurring spin reporters nitrogen-14 and phosphorus-31 present in the hydrophilic DMPC headgroup region, even fatty acid induced changes at the membrane interface could be detected, an observation reflecting changes in the lipid headgroup dynamics.

[Analysis of the impurity of bacterium source of standard endotoxin by gas chromatography/mass spectrometry].

To analyse the impurity of bacterium source of standard endotoxin, 3-hydroxy fatty acid species in different endotoxin standards was determined by gas chromatography/mass spectrometry (GC/MS) using N, O-bis (trimethylsilyl) trifluoroacetamide as the silanizing reagent. GC/MS analysis was performed using a gas chromatograph equipped with a 60 m x 0.25 mm i. d. DB-5 fused silica capillary column and an injector at 250 degrees C. Helium was used as the carrier gas under a constant pressure of 206 kPa. The oven was programmed at a rate of 5 degrees C /min from 90 degrees C (held for 5 min) to 280 degrees C (held for 5 min). The sample size was 1 microL. The transfer line was kept at 280 degrees C. The quadrupole mass spectrometer was operated in electron impact (EI) ionization mode, and the temperature of the source was kept at 250 degrees C. The kind of 3-hydroxy fatty acids in 9 000 EU/tube national standard endotoxin, 20 EU/tube working standard endotoxin, Escherichia coli, Pseudomonas aeruginosa and deionized water were determined to study the purity of bacterium source of the standard endotoxin. It was shown that 9 000 EU/tube endotoxin standard and Escherichia coli only contained 3-hydroxytetradecanoic acid. There was 3-hydroxydodecanoic acid in 20 EU/tube working standard endotoxin, which indicated the presence of impurity of bacterium source.

Novosphingobium pentaromativorans sp. nov., a high-molecular-mass polycyclic aromatic hydrocarbon-degrading bacterium isolated from estuarine sediment.

A Gram-negative, yellow-pigmented, halophilic bacterial strain US6-1T, which degrades high-molecular-mass polycyclic aromatic hydrocarbons of two to five rings, was isolated from muddy sediment of Ulsan Bay, Republic of Korea. The 16S rRNA gene of the isolate showed high sequence similarity to Novosphingobium subarcticum (96.23 %) and Sphingopyxis alaskensis (96.18 %); however, the isolate formed a distinct phyletic line within the genus Novosphingobium. DNA-DNA relatedness between US6-1T and the closest strain N. subarcticum revealed that strain US6-1T was independent from this species. Isolate US6-1T had ubiquinone 10 and a DNA G + C ratio of 61.1 mol%. Major fatty acids were octadecanoic acid (18 : 1omega7), hexadecanoic acid (16 : 1omega7) and 2-hydroxy-myristic acid (14 : 0 2-OH). On the basis of polyphasic taxonomic evidence, strain US6-1T is proposed to represent a novel species in the genus Novosphingobium for which the name Novosphingobium pentaromativorans sp. nov. is proposed. The type strain is US6-1T (= KCTC 10454T = JCM 12182T).

Identification of chlorinated fatty acids in fish by gas chromatography/mass spectrometry with negative ion chemical ionization of pentafluorobenzyl esters.

This paper reports the development of a technique for identifying and confirming chlorinated fatty acids previously detected in fish by gas chromatography (GC) with halogen-specific detection (XSD). Fatty acid methyl esters (FAMEs) including chlorinated FAMEs within fractions of reversed-phase high-performance liquid chromatography of transesterified fish extracts were derivatized to pentafluorobenzyl esters, which were subjected to GC/mass spectrometry (MS) with negative ion chemical ionization (NICI). Pentafluorobenzyl esters displayed reasonably good GC characteristics, a very high ionization efficiency and a low degree of fragmentation. Chloride ion chromatograms extracted at m/z 35 and 37 from full scans were utilized for locating traces of chlorinated unknowns in the GC elution profile so that their mass spectra could be readily displayed. Significant ions displayed in the mass spectrum scanned in a narrow range of retention time where a chlorinated unknown was located were evaluated using ion chromatograms extracted at the m/z of these ions. The chromatographic peaks of those ions derived from the analyte were expected to center at that specific retention time, whereas those originating from matrix compounds were not. The isotopic patterns of chlorinated ions were also examined against their theoretical relative abundances. Using this approach, three metabolism-related dichloro fatty acids previously identified by GC/XSD in filet extracts of white sucker sampled downstream from a bleached kraft pulp mill were confirmed: dichlorooctadecanoic, dichlorohexadecanoic and dichlorotetradecanoic acids. In addition, an isomer of dichlorotetradecanoic acid was found in a reference fish sample. As sample preparation is critical in this application, improved conditions for hydrolysis and pentafluorobenzyl esterification are also discussed.

Detoxification of endotoxin by endodontic irrigants and calcium hydroxide.

The effects of endodontic irrigants and calcium hydroxide on lipopolysaccharide (LPS; endotoxin) were analyzed using the highly selective technique of mass spectrometry/gas chromatography with selected ion monitoring. An aqueous solution of LPS was mixed with one of a variety of endodontic irrigants for 30 min. Because it is a commonly used interappointment dressing, calcium hydroxide was also applied to LPS for 1, 2, or 5 days. LPS inactivation was measured by quantitation of free fatty acid release. Water, EDTA, ethanol, 0.12% chlorhexidine, chlorhexidine + sodium hypochlorite, and sodium hypochlorite alone showed little breakdown of LPS. Long-term calcium hydroxide--as well as 30-min exposure to an alkaline mixture of chlorhexidine, ethanol, and sodium hypochlorite--did detoxify LPS molecules by hydrolysis of ester bonds in the fatty acid chains of the lipid A moiety.

Sphingomonas pituitosa sp. nov., an exopolysaccharide-producing bacterium that secretes an unusual type of sphingan.

Strain EDIVT, an exopolysaccharide-producing bacterium, was subjected to polyphasic characterization. The bacterium produced copious amounts of an extracellular polysaccharide, forming slimy, viscous, intensely yellow-pigmented colonies on Czapek-Dox (CZD) agar. The culture fluids of the liquid version of CZD medium were highly viscous after cultivation for 5 d. Cells of strain EDIVT were Gram-negative, catalase-positive, oxidase-negative, nonspore-forming, rod-shaped and motile. Comparisons of 16S rDNA gene sequences demonstrated that EDIVT clusters phylogenetically with the species of the genus Sphingomonas sensu stricto. The G+C content of the DNA (64.5 mol%), the presence of ubiquinone Q-10, the presence of 2-hydroxymyristic acid (14:0 2-OH) as the major hydroxylated fatty acid, the absence of 3-hydroxy fatty acids and the detection of sym-homospermidine as the major component in the polyamine pattern, together with the presence of sphingoglycolipid, supported this delineation. 16S rDNA sequence analysis indicated that strain EDIVT is most closely related (99.4% similarity) to Sphingomonas trueperi LMG 2142T. DNA-DNA hybridization showed that the level of relatedness to S. trueperi is only 45.5%. Further differences were apparent in the cellular fatty acid profile, the polar lipid pattern, the Fourier-transform infrared spectrum and whole-cell proteins and in a number of biochemical characteristics. On the basis of the estimated phylogenetic position derived from 16S rDNA sequence data, DNA-DNA reassociation and phenotypic differences, strain EDIVT (= CIP 106154T = DSM 13101T) was recognized as a new species of Sphingomonas, for which the name Sphingomonas pituitosa sp. nov. is proposed. A component analysis of the exopolysaccharide (named PS-EDIV) suggested that it represents a novel type of sphingan composed of glucose, rhamnose and an unidentified sugar. Glucuronic acid, which is commonly found in sphingans, was absent. The mean molecular mass of PS-EDIV was approximately 3 x 10(6) Da.

Mutation of the htrB gene in a virulent Salmonella typhimurium strain by intergeneric transduction: strain construction and phenotypic characterization.

The htrB gene product of Haemophilus influenzae contributes to the toxicity of the lipooligosaccharide. The htrB gene encodes a 2-keto-3-deoxyoctulosonic acid-dependent acyltransferase which is responsible for myristic acid substitutions at the hydroxy moiety of lipid A beta-hydroxymyristic acid. Mass spectroscopic analysis has demonstrated that lipid A from an H. influenzae htrB mutant is predominantly tetraacyl and similar in structure to lipid IV(A), which has been shown to be nontoxic in animal models. We sought to construct a Salmonella typhimurium htrB mutant in order to investigate the contribution of htrB to virulence in a well-defined murine typhoid model of animal pathogenesis. To this end, an r- m+ galE mutS recD strain of S. typhimurium was constructed (MGS-7) and used in inter- and intrastrain transduction experiments with both coliphage P1 and Salmonella phage P22. The Escherichia coli htrB gene containing a mini-Tn10 insertion was transduced from E. coli MLK217 into S. typhimurium MGS-7 via phage P1 and subsequently via phage P22 into the virulent Salmonella strain SL1344. All S. typhimurium transductants showed phenotypes similar to those described for the E. coli htrB mutant. Mass spectrometric analysis of the crude lipid A fraction from the lipopolysaccharide of the S. typhimurium htrB mutant strain showed that for the dominant hexaacyl form, a lauric acid moiety was lost at one position on the lipid A and a palmitic acid moiety was added at another position; for the less abundant heptaacyl species, the lauric acid was replaced with palmitoleic acid.

Effects of frame size and time-on-feed on carcass characteristics, sensory attributes, and fatty acid profiles of steers.

Weaned British x continental crossbred steers (n = 108, 7 to 8 mo of age) of medium or large frame were used in a replicated experiment with a 2 x 4 factorial arrangement of treatments over 2 yr. Management regimens consisted of backgrounding for 150 d and finishing for 0, 30, 60, and 90 d. Carcass data were collected, and samples from the longissimus muscle were analyzed for long-chain fatty acids, cholesterol, and the percentage of fat. Duration of finishing was a source of variation for hot carcass weight, marbling, percentage of kidney, pelvic, and heart fat, fat thickness, yield and quality grades, cooking loss, flavor intensity, and stearic, oleic, and linolenic acids (P < .05). Myristic, palmitic, and margaric acids were negatively correlated (P < .05) with juiciness and with "cowy" and "painty" taste characteristics. Frame score did not influence long-chain fatty acids; however, there was a relationship between long-chain fatty acids and management regimen. Results suggest that feeding steers a finishing diet up to 90 d after backgrounding for 150 d has a positive influence on carcass characteristics without affecting cholesterol.

Density dependent change of myristoylated proteins in C3H10T1/2 fibroblasts and their transformants.

We have examined the pattern of protein myristoylation in C3H10T1/2 fibroblasts during cell growth. During the growing phase of 10T1/2 cells, several proteins were radiolabelled with [3H]myristate, and among them proteins with molecular masses of 22, 35, a doublet of 42-45 and 67 kDa were labelled predominantly. The extent of myristoylation in each of these proteins changed with cell density. The amount of radioactivity incorporated into the 22 kDa protein in 10T1/2 cells decreased with increasing cell density and remained at a low level during the stationary phase. In contrast, the incorporation into the 67 kDa protein increased parallel to cell density. The density-dependent change of myristoylation was not observed in any of the transformants of 10T1/2 cells thus far examined. The 67 kDa protein was identified as MARCKS (myristoylated alanine-rich C kinase substrate) by immunoprecipitation with an anti-MARCKS antibody. By Western blot analysis, we found that the amount of MARCKS in 10T1/2 cells increased significantly analogous with cell density. Therefore, it is possible that MARCKS and the 22 kDa protein play a role in contact-mediated cell signalling in 10T1/2 cells, but the mechanism is lost in transformed cells.

Effect of medium-chain fatty acids in mould ripened cheese on the growth of Listeria monocytogenes.

Listeria monocytogenes and List. innocua were isolated from commercial soft ripened and blue-veined cheeses manufactured in France, mainly from Brie cheese made from unpasteurized milk. Five isolates were List. monocytogenes serotype 1/2 and two were List. innocua. Examination of Bleu d'Auvergne cheese with the cryoscanning electron microscope showed that many conidia spores were present in the blue veins in close contact with the cheese surface. There were few conidia spores in the Brie, mostly on the outside of the cheese but not in contact with the surface. High concentrations of free dodecanoic (lauric) acid (1.77-2.50 g/kg cheese) and tetradecanoic (myristic) acid (2.54-6.38 g/kg cheese) were found in the veins of the blue cheese, but concentrations in the white regions were much lower. Free lauric and myristic acids were not detected in the Brie cheeses. There was no difference in the overall fatty acid composition of the fat in the surface ripened and blue-veined cheeses, although higher concentrations of free medium-chain fatty acids were found in a blue cheese compared with a surface ripened cheese. The pH and fat content were higher in regions with obvious fungal growth, the blue veins of Fourme d'Ambert and the rind of Brie. Free lauric acid dissolved in butteroil inhibited multiplication in broth at pH 7.0 of a test strain of List. monocytogenes isolated from Bleu d'Auvergne. Some inhibition was seen with hexanoic, octanoic, decanoic and tetradecanoic acids. We suggest that the presence of localized concentrations of free medium-chain fatty acids (dissolved in the fat) in the blue veins of blue mould ripened cheese could act as natural preservatives and inhibit the growth of listerias in conditions where (if present), one would otherwise expect them to grow.