Volatile End Products Research Articles

Analysis of volatile compounds of Lentinula edodes grown in different culture substrate formulations.

Volatile compounds of Lentinula edodes grown in different culture substrate (CS) formulations were analyzed to reveal (i) the relationship between volatile compound production and CS formulations, (ii) the contribution of volatile compounds to L. edodes flavor, (iii) the activities of LOX and γ-GGT enzymes, (iv) γ-GGT gene expression, and (v) the correlation between enzyme activity and volatile compound production. Our results showed that 82 kinds of volatile compounds were analyzed; 25 volatile compounds were considered key flavor components, and sulfur containing compounds, eight-carbon compounds, and aldehyde compounds also had great contributions to mushroom flavor. Bagasse could be used as a partial substitute for sawdust as a carbon source. LOX and γ-GGT activities showed a weak correlation with the volatile end products. The results indicated that the mechanisms by which CS formulations influence volatile compounds production were complex.

Shock-wave processing of C60 in hydrogen

Context. Interstellar carbonaceous particles and molecules are subject to intense shocks in astrophysical environments. Shocks induce a rapid raise in temperature and density which strongly affects the chemical and physical properties of both the gas and solid phases of the interstellar matter. Aims. The shock-induced thermal processing of C60 particles in hydrogen has been investigated in the laboratory under controlled conditions up to 3900 K with the help of a material shock-tube. Methods. The solid residues generated by the exposure of a C60/H2 mixture to a millisecond shock wave were collected and analyzed using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman micro-spectroscopy, and infrared micro-spectroscopy. The gaseous products were analyzed by Gas Chromatography and Cavity Ring Down Spectroscopy. Results. Volatile end-products appear above reflected shock gas temperatures of ~2540 K and reveal the substantial presence of small molecules with one or two C atoms. These observations confirm the role played by the C2 radical as a major product of C60 fragmentation and less expectedly highlight the existence of a single C atom loss channel. Molecules with more than two carbon atoms are not observed in the post-shock gas. The analysis of the solid component shows that C60 particles are rapidly converted into amorphous carbon with a number of aliphatic bridges. Conclusions. The absence of aromatic CH stretches on the IR spectra indicates that H atoms do not link directly to aromatic cycles. The fast thermal processing of C60 in H2 over the 800–3400 K temperature range leads to amorphous carbon. The analysis hints at a collapse of the cage with the formation of a few aliphatic connections. A low amount of hydrogen is incorporated into the carbon material. This work extends the range of applications of shock tubes to studies of astrophysical interest.

Elucidation of the biochemical pathway of 2-phenylethanol from shikimic acid using isolated protoplasts of rose flowers

The isolated protoplasts of rose flowers were used to investigate the metabolic pathway in rose flower leading from shikimic acid or L-phenylalanine (L-Phe) to 2-phenylethanol (2PE), a dominant volatile compound in hybrid roses such as Rosa damascena Mill., R. 'Hoh-Jun', and R. 'Yves Piaget'. Deuterium-labeled L-Phe ([2H8]L-Phe) was supplied to the protoplasts isolated from R. 'Yves Piaget' petals. The volatile end products ([2Hn]-2PE, n=6-8) and their related intermediates ([2Hn]phenylacetaldehyde, n=6-8) were detected in the protoplasts by gas chromatography-mass spectrometry (GC-MS). In addition, we chemically synthesized [2,3,4,5,6-13C5]shikimic acid, a new stable isotopomer, to investigate the formation of 2PE from shikimic acid by GC-MS and nuclear magnetic resonance. We proposed the hypothetical biochemical pathway of 2PE from shikimic acid via chorismic acid, L-Phe, and phenylacetaldehyde. This protoplast system facilitates findings of metabolic intermediates and simplifies the complex branching biosynthetic pathways of floral scents to distinct individual events.

Understanding in vivo benzenoid metabolism in petunia petal tissue.

In vivo stable isotope labeling and computer-assisted metabolic flux analysis were used to investigate the metabolic pathways in petunia (Petunia hybrida) cv Mitchell leading from Phe to benzenoid compounds, a process that requires the shortening of the side chain by a C(2) unit. Deuterium-labeled Phe ((2)H(5)-Phe) was supplied to excised petunia petals. The intracellular pools of benzenoid/phenylpropanoid-related compounds (intermediates and end products) as well as volatile end products within the floral bouquet were analyzed for pool sizes and labeling kinetics by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry. Modeling of the benzenoid network revealed that both the CoA-dependent, beta-oxidative and CoA-independent, non-beta-oxidative pathways contribute to the formation of benzenoid compounds in petunia flowers. The flux through the CoA-independent, non-beta-oxidative pathway with benzaldehyde as a key intermediate was estimated to be about 2 times higher than the flux through the CoA-dependent, beta-oxidative pathway. Modeling of (2)H(5)-Phe labeling data predicted that in addition to benzaldehyde, benzylbenzoate is an intermediate between l-Phe and benzoic acid. Benzylbenzoate is the result of benzoylation of benzyl alcohol, for which activity was detected in petunia petals. A cDNA encoding a benzoyl-CoA:benzyl alcohol/phenylethanol benzoyltransferase was isolated from petunia cv Mitchell using a functional genomic approach. Biochemical characterization of a purified recombinant benzoyl-CoA:benzyl alcohol/phenylethanol benzoyltransferase protein showed that it can produce benzylbenzoate and phenylethyl benzoate, both present in petunia corollas, with similar catalytic efficiencies.

An Examination of ‘Unidentified’Prevotella (Formerly PINLO) using RAPD-PCR and Partial 16S rRNA Gene Sequencing

Prevotella intermedia - and Prevotella nigrescens -like organisms (PINLO) have been described as organisms which are phenotypically and biochemically similar to P. intermedia and P. nigrescens and the species P. pallens was created to include some of them. Other PINLO groups which do not fit the definition of P. pallens exist, and in this study these ‘unidentified’Prevotella sp. were compared with P. corporis, P. intermedia, P. nigrescens and P. pallens using commercial identification kits, GLC, RAPD-PCR and partial 16S rRNA gene sequencing. The Rapid ID 32 A and the RapID ANA II system both identified all ‘unidentified’Prevotella as P. intermedia. Similarly they gave this identification to all the species tested (with the exception of P. corporis using the RapID ANA II system) clearly demonstrating biochemical similarities. Gas liquid chromatography (GLC) analysis of the volatile end-products of fermentation could not distinguish between strains. RAPD-PCR using arbitrary primer L10 demonstrated intra-species homogeneity within PINLO strains with amplification profiles which differed from other Prevotella species tested. Cluster analysis of the amplification profiles confirmed species divisions and yielded a distinct ‘unidentified’Prevotella cluster. Comparison of partial 16S rDNA sequences displayed 98% sequence similarity between the ‘unidentified’Prevotella strains, although 2 strains, HST 1156 and HST 2160 displayed 100% identity. The highest similarity between groups was seen between ‘unidentified’Prevotella strains and P. corporis (approximately 94% similarity). The DNA techniques used here confirm that ‘unidentified’Prevotella strains are distinct from the other species ofPrevotella tested, including P. pallens. Partial 16S rDNA sequence comparisons suggested a close relationship with P. corporis.

Chemical state of molybdenum, tungsten and element 106 in chlorinating gases

We have made a quantitative study of the thermochromatographic behavior of short-lived isotopes of W under conditions similar to those of our recent chemical identification experiments with element 106. The analogous experiments with Mo isotopes performed earlier at lower counting statistics gave results similar to those with W. The experimental data were analyzed from the point of view of the thermodynamics and kinetics of the possible reactions, and of the volatility properties of the known species which could be involved. We concluded that with SOCl2 and O2 in the carrier gas and with an actual run time of several minutes or more, the end products are oxotetrachlorides. But, at first, less volatile dioxodichlorides are formed within no more than few seconds, to be subsequently relatively slowly converted to more volatile end products. Element 106 was most probably also deposited on the quartz surface as SgO2Cl2, but decayed before the transformation to SgOCl4 could be completed.

Erwinia carotovora subsp. odorifera subsp. nov., Associated with Odorous Soft Rot of Chicory (Cichorium intybus L.)

Eleven strains of Erwinia carotovora that were isolated mainly, but not exclusively, from slimy rot of witloof chicory and were previously designated “atypical” E. carotovora subsp. atroseptica strains were characterized and compared with strains of E. carotovora subsp. carotovora, E. carotovora subsp. atroseptica, and Erwinia chrysanthemi (including the type strains). The 11 atypical E. carotovora subsp. atroseptica strains produced a typical bananalike odor when they were inoculated onto witloof chicory leaves. DNA-DNA homology experiments, biochemical tests, tests to determine carbon utilization patterns, and tests to identify the volatile metabolites produced from rotting witloofs were performed. The volatile end products of witloof decay were analyzed by gas chromatography. Alcohols, methylketones, and ethylacetate were produced by all of the Erwinia strains which we studied, whereas propyl acetate, isobutyl acetate, isoamyl acetate, and 2-actamyl acetate were produced only by the flavoring witloof soft-rot strains. A DNA relatedness study was performed by hybridizing DNAs with a tritium-labeled DNA and estimating the δTm values (δTm is the difference between the thermal denaturation midpoint of a homoduplex and the thermal denaturation midpoint of a heteroduplex). The 11 flavoring strains constituted a tight DNA hybridization group (79 to 91% related to type strain CFBP 1878 isolated from witloof). Strains of E. carotovora subsp. carotovora were 59 to 88% related to strain CFBP 1878T (T = type strain) (δTm range, 3 to 4.5°C), indicating that they belonged to the same species but another subspecies. E. carotovora subsp. atroseptica and E. carotovora subsp. betavasculorum appeared to be less closely related to strain CFBP 1878T than E. carotovora subsp. carotovora was, exhibiting 53% homology (δTm, 7°C) and 48 to 51% homology (δTm, 8.5°C), respectively, with strain CFBP 1878T. Therefore, we propose that the 11 flavoring strains are members of a new subspecies, Erwinia carotovora subsp. odorifera. We examined 95 biochemical characteristics, API strip tests, and assimilation tests in Biotype galleries and identified nine tests which can be used for phenotypic differentiation of the new subspecies.

Quantification of the end-products of the acetone-butanol-ethanol fermentation by gas chromatography

A range of packing materials for analyzing volatile end-products of the acetone-butanol-ethanol (ABE) fermentation was examined. Chromosorb W-AW/10% Carbowax 20 M- TPA + 0.1% HPO 3 was found to produce the most precise results. It was not necessary to incorporate formic acid vapor in the carrier gas when the chromatographic surfaces were systematically deactivated by acid washing and the samples acidified. Porapak Q and Chromosorb 101 produced the least precise results of the eight materials tested. The chromatographic properties of Chromosorb 101 deteriorated when formic acid vapor was included in the carrier gas.

The contribution of a partial tricarboxylic acid cycle to volatile end-products in thiabendazole-resistant and susceptible Trichostrongylus colubriformis

Acetate, propionate, ethanol and propanol were the predominant end-products released during incubation of a thiabendazole resistant and a susceptible strain of Trichostrongylus colubriformis. The parasites in all the incubations appeared to be deficient in reducing equivalents if the end-products arose from the classical catabolic pathway through fumarate reductase (EC 1.3.1.6). Possible alternative pathways for accounting for redox balance, including β-oxidation, the pentose phosphate pathway and amino acid metabolism were investigated. Palmitate was oxidised aerobically. Radiolabelled tricarboxylic acid cycle intermediates, citrate and α-ketoglutarate, were decarboxylated to 14CO 2 indicating that at least a partial tricarboxylic acid cycle to succinyl-CoA via α-ketoglutarate operates both anaerobically and aerobically in T. colubriformis. These data and the pattern of end-products suggest the presence of two pathways to propanol and propionate either through fumarate reduction or α-ketoglutarate oxidation. T. colubriformis may apportion carbon flow through these pathways to maintain a stable redox ratio. Similar calculations on previously reported data indicate that both pathways may also operate in Haemonchus contortus. Exposure of resistant T. colubriformis to thiabendazole under anaerobic conditions caused an increased accumulation of end-products, especially propanol, in the incubation medium. The α-ketoglutarate pathway may lower the dependence of the parasite on the fumarate reductase route which is sensitive to thiabendazole. The operation of the α-ketoglutarate pathway, with propanol as an end-product, may provide a mechanism for regulating redox balance in trichostrongylidae.

Catabolism of hamamelose. The anaerobic dissimilation of D-hamamelose by Kluyvera citrophila 627.

Hamamelose (2‐C‐hydroxymethyl‐d‐ribose) is a common sugar of green land plants. However, until now, all experiments failed to show dissimilation of this sugar by its producers or by soil microorganisms. For investigation of its biological degradation, microorganisms were used which had been isolated from plant material (leaves of Primula clusiana Tausch). These microorganisms belong to the Enterobacteriaceae and are almost identical to those described by Asai et al. (1956, 1962) as Kluyvera citrophila. They differ from the ATCC strains of this organism by their ability to grow on hamamelose.Isotope studies using 14C‐labelled hamamelose and glucose (for comparison) as substrates were carried out to elucidate the biochemical route of hamamelose catabolism. This degradation leads to CO2 under aerobic conditions and to lactate, succinate, formate, acetate and ethanol under anaerobic ones. Glucose dissimilation proceeds via glycolysis and leads to the same end‐products. As intermediates of the biological degradation of hamamelose, hamamelose 21‐phosphate, fructose 1‐phosphate, fructose 1, 6‐bisphosphate and phosphoglycerate were identified. Thus the biochemical route of hamamelose dissimilation appears to be rather similar to glycolysis. The following sequence is proposed: hamamelose → hamamelose 21‐phosphate → fructose 1‐phosphate → fructose 1, 6‐bisphosphate → phosphoglycerate → pyruvate → volatile end‐products. Differences from the glycolytic pathway occur at step 2 in which there is a rearrangement of the carbon skeleton and at step 3, in which fructose 1‐phosphate instead of fructose 6‐phosphate has to be phosphorylated.

Vapor Analysis of Fermented Spanish‐type Green Olives by Gas Chromatography

SUMMARY: Five major components were detected gas chromatographically in the head‐space vapor (HSV) of Spanish‐type green olives fermented by pure cultures of Lactobacillus plantarum, Pediococcus cerevisiae and Leuconostoc mesenteroides. Three of these compounds were identified as acetaldehyde, methyl sulfide, and ethanol. The same compounds were present in unfermented olives but in different amounts. Olives that had undergone a natural fermentation contained the above five compounds, and, in addition, a varying number of other compounds. These results indicated that HSV analysis may be a rapid method for detecting volatile end products resulting from the metabolism of various microorganisms. A high ethanol content was found in olive brines that contained a predominance of yeasts. Abnormal fermentations gave unique HSV profiles, one of which indicated a high level of 2‐butanol. Methyl sulfide was found to be a major odor component of fermented as well as unfermented olives. Acetaldehyde and ethanol contributed secondarily to the odor. Primary contributions of fermentation by the above lactic acid bacteria to the flavor of olives were: (1) production of a desirable level of acidity, and (2) utilization of fermentable sugars to the exclusion of microorganisms which produce metabolic end products with undesirable flavor characteristics.