Studies on the Changes of Meat Fats by Various Processings

Data are presented to show the gas chromatographic identification of a total of 18 saturated aliphatic γ- and δ-lactones obtained from melted beef depot fat, namely, δ-C₆, γ-C₇, γ-C₈, γ-C₉, and a homologous series of γ- and δ-lactones of the even-carbon numbers C₁₀ to C₁₆ and of smaller amount of the odd-carbon numbers C₁₁ to C₁₅. These lactones were isolated by steam distillation and silicic acid adsorption chromatography, and identified through gas chromatography and infrared spectroscopy.

Lactones obtained had a peach-like flavor, and it was suggested that lactones were important in heated beef fat as the flavor compounds.     

Comparative alkane chemistry of Parthenium argentatum (guayule) and some F1 hybrids

The leaf alkanes of Parthenium argentatum (guayule), P. tomentosum var. stramonium, P. fruticosum var. trilobatum, and the first filial (F₁) generations obtained from crosses with guayule were investigated by GC and mass spectrometry and shown to be useful in chemotaxonomic studies. The identified n-alkanes ranged from C₁₉ to C₄₀ with either n-C₂₉ or n-C₃₁ as the main component. The alkane chemistry of guayule with n-C₃₁ being the main component predominated in most of the F₁ hybrids. The presence of iso-branched alkanes (C₂₇, C₂₉, C₃₁) in P. tomentosum and its hybrids could be detected by GC/MS. These preliminary investigations indicate that epicuticular wax alkanes can be useful in inheritance studies of guayule and its hybrids.     

Dependence of the hydrocarbon constituents of the leaf waxes of Khaya species on leaf age

The hydrocarbon constituents of the leaf waxes of eight species of Khaya were analysed for taxonomic purposes using GLC. The leaf waxes contained neither isoalkanes nor alkanes and the bulk of the n-alkanes were in the range of C₂₅ to C₃₃, odd-carbon number compounds predominating. It was found that the percentage composition of the n-alkane constituents of the leaf waxes varied with the age of leaves, young leaves having n-C₂₉ as the most abundant alkane, whereas older leaves had n- C₃₁.     

Hydrocarbons,sterols and tocopherols in the seeds of six Adansonia species

The composition of the unsaponifiable matter of the lipids of six Adansonia species (A. grandidieri, A. za, A. fony, A. madagascariensis, A. digitata and A. suarezensis) was investigated. The total unsaponifiable content, its general composition and the identity of the components of the hydrocarbon, sterol and tocopherol fractions are presented. The unsaponifiable content in oil ranges from 0.4 to 1.1% (hexane method) and from 0.6 to 2.2% (diethyl ether method). In two species (A. grandidieri and A. suarezensis) the major components are 4-demethylsterols (23–42%) tocopherols (37-10%) and hydrocarbons (15–17%). In both species examined, eight 4-demethylsterols occur in the sterol fraction with sitosterol (81–88%) being predominant. Among the four tocopherols present, γ-tocopherol (68–98%) is the major compound. Each Adansonia species shows a characteristic gas liquid chromatography pattern for the hydrocarbon fraction. Squalene is the major component for five species (40–75%). Iso-, anteiso- and other branched hydrocarbons were not identified but were present in small amounts in comparison with n-alkanes. The dominance of odd- over even-carbon number chain length of n-alkanes was not observed in any species. The results show that C₂₂, C₂₅, C₂₆, C₂₇, C₂₈ and C₂₉ are the most frequent major constituents.     

Extractive compounds of birch buds (<Emphasis Type="Italic">Betula pendula</Emphasis> Roth.): I. Composition of fatty acids,hydrocarbons, and esters

This is the first report devoted to study of the hydrocarbon composition of the extract of buds of European birch Betula pendula (family Betulacea). We have identified saturated (C₁₆ to C₂₈, even number of carbon atoms) and unsaturated (linoleic and linolenic) fatty acids, β-caryophyllene, α-humulene, and the components of epicuticular waxes of cover scales, such as n-alkanes (C₂₁ to C₂₆), esters of fatty acids (C₁₆ to C₂₈, even number of carbon atoms), and fatty alcohols (C₁₈ to C₃₀, even number of carbon atoms). The gas chromatographic retention indices of all identified compounds have been determined.     

The properties of hydrocarbon-oxidizing bacteria isolated from the oilfields of Tatarstan, western Siberia, and Vietnam

Eleven strains of hydrocarbon-oxidizing bacteria, isolated from oilfields and representing the genera Rhodococcus, Gordonia, Dietzia, and Pseudomonas, were characterized as mesophiles and neutrophiles. Rhodococci were halotolerant microorganisms growing in a media containing up to 15% NaCl. All the strains oxidized n-alkanes of crude oil. An influence of the cultivation temperatures (28 or 45°C) and organic supplements on the degradation of C₁₂-C₃₀ n-alkanes in oxidized oil by two bacterial strains of the genus Pseudomonas was shown. The introduction of acetate, propionate, butyrate, ethanol, and sucrose led mainly to decreased oxidation of petroleum paraffins. At certain cultivation temperatures, the addition of volatile fatty acid salts increased the content of certain n-alkanes in oxidized oil as compared to crude oil.     

Biosynthetic and environmental effects on the stable carbon isotopic compositions of anteiso- (3-methyl) and iso- (2-methyl) alkanes in tobacco leaves

Nicotiana tabacum is the only plant known to synthesise large quantities of anteiso- (3-methyl) alkanes and iso- (2-methyl) alkanes. We investigated the carbon isotope ratios of individual long-chain n-alkanes, anteiso- and iso-alkanes (in the C₂₉-C₃₃ carbon number range) extracted from tobacco grown in chambers under controlled conditions to confirm the pathway used by the tobacco plant to synthesise these particular lipids and to examine whether environmental data are recorded in these compounds. Tobacco was grown under differing temperatures, water availabilities and light intensities in order to control its stable carbon isotope ratios and evaluate isotopic fractionations associated with the synthesis of these particular lipids. The anteiso-alkanes were found to have a predominant even-carbon number distribution (maximising at C₃₂), whereas the iso-alkanes exhibit an odd-carbon number distribution (maximising at C₃₁). Iso-alkanes were relatively more abundant than the anteiso-alkanes and only two anteiso-alkanes (C₃₀ and C₃₂) were observed.The anteiso-alkanes and iso-alkanes were found to be enriched in ¹³C by 2.8-4.3‰ and 0-1.8‰ compared to the n-alkanes, respectively, consistent with different biosynthetic precursors. The assumed precursor for the odd-carbon-numbered iso-alkanes is iso-butyryl-CoA (a C₄ unit derived from valine) followed by subsequent elongation of C₂ units and then decarboxylation. The assumed precursor for even-carbon-numbered anteiso-alkanes is α-methylbutyryl-CoA (a C₅ unit derived from isoleucine) and subsequent elongation by C₂ units followed by decarboxylation. The ratio of carbon atoms derived from α-methylbutyryl-CoA and subsequent C₂ units (from malonyl-CoA) is 1:5 for the biosynthesis of a C₃₀anteiso-alkane. The ratio of carbon atoms derived from iso-butyryl-CoA and subsequent C₂ units (from malonyl-CoA) is 4:25 for the synthesis of a C₂₉iso-alkane. An order of ¹³C depletion n-alkanes > iso-alkanes > anteiso-alkanes is evident from compound specific isotope data. This trend can probably be attributed to the ratio of the two different sources of carbon atoms in the final wax components.Higher water availability generally results in more depleted stable carbon isotope ratios due to maximised discrimination during carboxylation, associated with less diffusional limitation. This was confirmed in the present study by compound specific isotope analyses of iso-alkanes, anteiso-alkanes and n-alkane lipids extracted from the tobacco leaves. Likewise, light intensity has been shown to influence plant bulk δ¹³C in previous studies. The carbon isotope ratios of n-alkanes in tobacco grown under low-light conditions were about 2‰ more depleted in ¹³C than those of lipids extracted from tobacco grown under elevated light conditions. A similar order of difference is observed for the iso-alkanes and anteiso-alkanes (1.8‰ and 1.9‰, respectively). A negligible depletion in carbon isotope ratios was observed for the iso-alkanes and anteiso-alkanes extracted from tobacco grown under elevated temperatures. These results are consistent with the work of Farquhar [Farquhar, G.D., 1980. Carbon isotope discrimination by plants: effects of carbon dioxide concentration and temperature via the ratio of intercellular and atmospheric CO₂ concentrations. In: Pearman, G.I. (Ed.), Carbon Dioxide and Climate: Australian Research. Springer, Berlin, pp. 105-110] where temperature appears to have only a minor effect on plant bulk δ¹³C.     

Lanostane triterpenes of Canscora decussata

From the aerial parts of Canscora decussata Schult (Gentianaceae), five triterpenes, viz. gluanone, canscoradione, friedelin, fridelan-3-β-ol, and β-amyrin, three sterols, viz. sitosterol, stigmasterol, and campesterol, besides liberal amount of a mixtures of n-alkanes (C₂₇-C₃₁) and n-alkanols (C₂₆-C₃₂) have been isolated. The identity of the compounds has been established by chemical transformations, spectral evidence, and by direct comparison, where possible, with authentic reference materials. Gluanone and canscoradione have not been encountered before in nature.     

Saturated and mono-unsaturated long-chain hydrocarbon profiles from mandarin juice sacs

The long-chain saturated and mono-unsaturated hydrocarbon content of the juice sacs of five mandarin cultivars (Mediterranean, Honey, Wilking, Kinnow, King) were examined. Normal homologues accounted for more than 47% of the saturated and more than 75% of the monoene hydrocarbons. In the saturated fraction the major hydrocarbon was n-C₂₅ but in the monoene fraction n-C₂₅ predominated in Kinnow and King while C₂₉ predominated in Mediterranean, Honey and Wilking. All five cultivars could be differentiated from each other and from other citrus species by their hydrocarbon patterns. The noticeably high normal/iso ratios of saturated C₂₃ and C₂₅ hydrocarbons previously shown to be characteristic of mandarin species, Citrus unshiu and C. reticulata, were also found in C. nobilis and C. deliciosa.     

A Hypothetical Cyclic Pathway for the Metabolism of Odd-carbon n-Alkanes or Propionyl-CoA via Seven-carbon Tricarboxylic Acids in Yeasts

An extensive study has been undertaken to elucidate the physiological significance of threo-D_s-2-methylisocitric acid produced mainly from odd-carbon n-alkanes by a mutant strain of Candida lipolytica. The mutant strain showed slower growth responses to odd-carbon n-alkanes, especially of shorter chain-length, and failed to utilize this acid as sole carbon source, whereas the parent strain and many other yeasts tested were able to utilize this acid. About one half of yeasts tested accumulated this acid extracellularly. Under a thiamine-deficient condition, amounts of pyruvate produced by the parent strain from odd-carbon n-alkanes were ten times as large as those from even-carbon n-alkanes. A scheme for the partial oxidation of propionyl-CoA to pyruvate via C₇-tricarboxylic acid by yeasts was supposed. This scheme may offer suggestion on the metabolism of propionyl-CoA by other living organisms. A hypothetical pathway of citrate accumulation from odd-carbon n-alkane was also presented.     

Effect of cell lipid composition on the formation of nonspecific antibiotic resistance in alkanotrophic rhodococci

The antibiotic resistance and lipid composition of rhodococci grown in rich organic media with gaseous or liquidn-alkanes were studied. Hydrocarbon-grown rhodococci exhibited an increased resistance to a wide range of antibiotics (aminoglycosides, linkosamides, macrolides, β-lactams, and aromatic compounds). The enhanced antibiotic resistance of rhodococci grown onn-alkanes correlated with an increased content of total cell lipids (up to 14–28%) and saturated straight-chain fatty acids (C_16:0, C_18:0, C_21:0) and was accompanied by the appearance of cardiolipin and phosphatidylglycerol in cells. These lipid compounds are supposed to promote the formation of nonspecific antibiotic resistance in rhodococci by decreasing the permeability of their cell envelope to antibiotics.     

Flavanone and other constituents from Onychium siliculosum

Two new compounds, onitinoside and onysilin along with the known compounds, pinostrobin, onitin, onitisin, campesterol, sitosterol and n-alkanes (C₂₅-C₃₃) were isolated from Onychium siliculosum. Onitinoside and onysilin were identified by spectral and chemical methods as 4-O-glucosyl-6-(2′-hydroxyethyl)-2,2,5,7-tetramethylindan-1-one and 5-hydroxy-6,7-dimethoxyflavanone, respectively.     

Aliphatic Hydrocarbons of Cladosporium resinae Cultured on Glucose,Glutamic Acid,and Hydrocarbons

The carbon source markedly influenced the qualitative and quantitative composition of cellular hydrocarbons in Cladosporium resinae. Total lipid and hydrocarbon content was greater in cells grown on n-alkanes than in cells grown on glucose or glutamic acid. Glucose-grown cells contained a spectrum of aliphatic hydrocarbons from C₇ to C₃₆; pristane and n-hexadecane comprised 98% of the total. Cells grown on glutamic acid contained C₇ to C₂₃ hydrocarbons; n-tridecane, n-tetradecane, n-hexadecane, and pristane made up 74% of the total. n-Decane-grown cells yielded C₈ to C₃₂ compounds, and n-hexadecane (96%) was the major hydrocarbon. Cells grown on individual n-alkanes from C₁₁ to C₁₅ all contained C₁₁ to C₂₈ hydrocarbons, and cells grown on n-hexadecane contained C₁₁ to C₃₂ hydrocarbons. In n-undecane-grown cells, n-hexadecane and pristane made up 92% of the total, but in cells grown on C₁₂ to C₁₆ n-alkanes the major cellular hydrocarbon was the one on which the cells were grown. This suggests that cells cultured on n-alkanes of C₁₂ or longer accumulate n-alkanes prior to oxidizing them.     

Authigenic mineralization and detrital clay binding by freshwater biofilms: The Brahmani river,India

This study sought to understand the origin and fate of one of the bitumen mounds found on the bottom of Lake Baikal. These mounds are located at a depth of 900 m beneath oil spots detected on the surface of Lake Baikal (53° 18′24^″, 108° 23′20^″). The two mounds were sampled with a manipulator from a “MIR” deep-water manned submersible. Mature mound No. 8 was subjected to chemical and microbiological studies. Mound No. 3 was subjected only to chemical studies; we failed to perform microbiological analyses of this mound for logistic reasons. Oil spots collected from the water surface, samples of mound No. 3 and No. 8, were subjected to GC/MS analysis. The water contained aliphatic hydrocarbons with chains between C₈ and C₂₃, with the most abundant chain length being C₁₈. Mound No. 3 with the most abundant chain length being C₁₈ actively released oil droplets into the water. It contained 770 mg/g of C₁₃-C₃₂ n-alkanes, with a maximum at C₂₃ (160 mg/g). Mound No. 8 was inactive and contained 148 mg/g of aliphatic C₂₂-C₃₄ n-alkanes, with a maximum at C₂₅. Mound No. 8 also consisted of 3% inorganic matter, 48% unresolved complex mixture (UCM) and less than 1% other compounds (polyaromatic hydrocarbons, isoprenoids, carotenoids, and hopanes). The core of this sample used as inoculate, yielded Rhodococci when cultivated on oil as the only source of carbon. Cultivation of the sample on agar-containing Raymond inorganic medium with crude West Siberian oil as the only source of carbon revealed colonies of these bacteria, which all appeared identical. PCR was performed with DNA isolated from 5 colonies, using primers for 16S rRNA genes. Comparison of the sequences of the 5 PCR products over a length of 714 bp revealed that they were almost identical. Phylogenetic analysis of these homologous sequences showed that they were similar to the corresponding sequences of the genus Rhodococcus. Substrate demands, the morphology of the colonies, and SEM and TEM data confirmed that the isolates obtained could indeed be Rhodococci. All of the isolates could grow in bulk cultures with inorganic medium supplemented with crude oil. Moreover, all of the isolates degraded aliphatic hydrocarbons with lengths between C₁₁ and C₂₉. C₂₃-C₂₉ hydrocarbons were degraded completely. The isolates could grow at 4–37°C. The most unexpected finding was that of the many microorganisms capable of consuming oil, only Rhodococci exhibited this ability in the inactive bitumen mound. The possible mechanisms of how crude oil is transformed into bitumen mounds and mature bitumen are discussed.     

Extractive compounds of birch buds (<Emphasis Type="Italic">Betula pendula</Emphasis> Roth.): II. Carbonyl compounds and oxides. Esters

This is the first report devoted to study of the hydrocarbon composition of the extract of buds of European birch Betula pendula (family Betulacea). We have identified saturated (C₁₆ to C₂₈, even number of carbon atoms) and unsaturated (linoleic and linolenic) fatty acids, β-caryophyllene, α-humulene, and the components of epicuticular waxes of cover scales, such as n-alkanes (C₂₁ to C₂₆), esters of fatty acids (C₁₆ to C₂₈, even number of carbon atoms), and fatty alcohols (C₁₈ to C₃₀, even number of carbon atoms). The gas chromatographic retention indices of all identified compounds have been determined.     

Further evidence for an elongation-decarboxylation mechanism in the biosynthesis of paraffins in leaves

In isolated tobacco leaves l-valine-U-¹⁴C gave rise to labeled even-numbered isobranched fatty acids containing 16 to 26 carbon atoms and iso C₂₉, iso C₃₁, and iso C₃₃ paraffins. l-Isoleucine-U-¹⁴C on the other hand produced labeled odd-numbered anteiso C₁₇ to C₂₇ fatty acids and anteiso C₃₀ and C₃₂ paraffins. Trichloroacetic acid inhibited the incorporation of isobutyrate into C₂₀ and higher fatty acids and paraffins without affecting the synthesis of the C₁₆ and C₁₈ fatty acids. Thus the very long branched fatty acids are biosynthetically related to the paraffins. In Senecio odoris leaves acetate-1-¹⁴C was incorporated into the paraffins (mainly n-C₃₁) only in the epidermis although acetate was readily incorporated into fatty acids in the mesophyll tissue. Similarly only the epidermal tissue incorporated acetate into fatty acids longer than C₁₈ suggesting that the epidermis is the site of synthesis of both paraffins and the very long fatty acids. In broccoli leaves n-C₁₂ acid labeled with ¹⁴C in the carboxyl carbon and ³H in the methylene carbons was incorporated into C₂₉ paraffin without the loss of ¹⁴C relative to ³H. Since n-C₁₈ acid is known to be incorporated into the paraffin without loss of carboxyl carbon these results suggest that the condensation of C₁₂ acid with C₁₈ acid is not responsible for n-C₂₉ paraffin synthesis in this tissue. Thus all the experimental evidence thus far obtained strongly suggests that elongation of fatty acids followed by decarboxylation is the most likely pathway for paraffin biosynthesis in leaves.     

Signature Lipids and Stable Carbon Isotope Analyses of Octopus Spring Hyperthermophilic Communities Compared with Those of Aquificales Representatives

The molecular and isotopic compositions of lipid biomarkers of cultured Aquificales genera have been used to study the community and trophic structure of the hyperthermophilic pink streamers and vent biofilm from Octopus Spring. Thermocrinis ruber, Thermocrinis sp. strain HI 11/12, Hydrogenobacter thermophilus TK-6, Aquifex pyrophilus, and Aquifex aeolicus all contained glycerol-ether phospholipids as well as acyl glycerides. The n-C_20:1 and cy-C₂₁ fatty acids dominated all of the Aquificales, while the alkyl glycerol ethers were mainly C_18:0. These Aquificales biomarkers were major constituents of the lipid extracts of two Octopus Spring samples, a biofilm associated with the siliceous vent walls, and the well-known pink streamer community (PSC). Both the biofilm and the PSC contained mono- and dialkyl glycerol ethers in which C₁₈ and C₂₀ alkyl groups were prevalent. Phospholipid fatty acids included both the Aquificales n-C_20:1 and cy-C₂₁, plus a series of iso-branched fatty acids (i-C_15:0 to i-C_21:0), indicating an additional bacterial component. Biomass and lipids from the PSC were depleted in ¹³C relative to source water CO₂ by 10.9 and 17.2‰, respectively. The C_20–21 fatty acids of the PSC were less depleted than the iso-branched fatty acids, 18.4 and 22.6‰, respectively. The biomass of T. ruber grown on CO₂ was depleted in ¹³C by only 3.3‰ relative to C source. In contrast, biomass was depleted by 19.7‰ when formate was the C source. Independent of carbon source, T. ruber lipids were heavier than biomass (+1.3‰). The depletion in the C_20–21 fatty acids from the PSC indicates that Thermocrinis biomass must be similarly depleted and too light to be explained by growth on CO₂. Accordingly, Thermocrinis in the PSC is likely to have utilized formate, presumably generated in the spring source region.     

Structure and Biosynthesis of Cuticular Lipids: Hydroxylation of Palmitic Acid and Decarboxylation of C(28), C(30), and C(32) Acids in Vicia faba Flowers

The structure and composition of the cutin monomers from the flower petals of Vicia faba were determined by hydrogenolysis (LiAlH₄) or deuterolysis (LiAlD₄) followed by thin layer chromatography and combined gas-liquid chromatography and mass spectrometry. The major components were 10, 16-dihydroxyhexadecanoic acid (79.8%), 9, 16-dihydroxyhexadecanoic acid (4.2%), 16-hydroxyhexadecanoic acid (4.2%), 18-hydroxyoctadecanoic acid (1.6%), and hexadecanoic acid (2.4%). These results show that flower petal cutin is very similar to leaf cutin of V. faba. Developing petals readily incorporated exogenous [1-¹⁴C]palmitic acid into cutin. Direct conversion of the exogeneous acid into 16-hydroxyhexadecanoic acid, 10, 16-dihydroxy-, and 9, 16-dihydroxyhexadecanoic acid was demonstrated by radio gas-liquid chromatography of their chemical degradation products. About 1% of the exogenous [1-¹⁴C]palmitic acid was incorporated into C₂₇, C₂₉, and C₃₁n-alkanes, which were identified by combined gas-liquid chromatography and mass spectrometry as the major components of the hydrocarbons of V. faba flowers. The radioactivity distribution among these three alkanes (C₂₇, 15%; C₂₉, 48%; C₃₁, 38%) was similar to the per cent composition of the alkanes (C₂₇, 12%; C₂₉, 43%; C₃₁, 44%). [1-¹⁴C]Stearic acid was also incorporated into C₂₇, C₂₉, and C₃₁n-alkanes in good yield (3%). Trichloroacetate, which has been postulated to be an inhibitor of fatty acid elongation, inhibited the conversion of [1-¹⁴C]stearic acid to alkanes, and the inhibition was greatest for the longer alkanes. Developing flower petals also incorporated exogenous C₂₈, C₃₀, and C₃₂ acids into alkanes in 0.5% to 5% yields. [G-³H]n-octacosanoic acid (C₂₈) was incorporated into C₂₇, C₂₉, and C₃₁n-alkanes. [G-³H]n-triacontanoic acid (C₃₀) was incorporated mainly into C₂₉ and C₃₁ alkanes, whereas [9, 10, 11-³H]n-dotriacontanoic acid (C₃₂) was converted mainly to C₃₁ alkane. Trichloroacetate inhibited the conversion of the exogenous acids into alkanes with carbon chains longer than the exogenous acid, and at the same time increased the amount of the direct decarboxylation product formed. These results clearly demonstrate direct decarboxylation as well as elongation and decarboxylation of exogenous fatty acids, and thus constitute the most direct evidence thus far obtained for an elongation-decarboxylation mechanism for the biosynthesis of alkanes.     

Formation of Polyesters by Pseudomonas oleovorans: Effect of Substrates on Formation and Composition of Poly-(R)-3-Hydroxyalkanoates and Poly-(R)-3-Hydroxyalkenoates

Pseudomonas oleovorans grows on C₆ to C₁₂n-alkanes and 1-alkenes. These substrates are oxidized to the corresponding fatty acids, which are oxidized further via the β-oxidation pathway, yielding shorter fatty acids which have lost one or more C₂ units. P. oleovorans normally utilizes β-oxidation pathway intermediates for growth, but in this paper we show that the intermediate 3-hydroxy fatty acids can also be polymerized to intracellular poly-(R)-3-hydroxyalkanoates (PHAs) when the medium contains limiting amounts of essential elements, such as nitrogen. The monomer composition of these polyesters is a reflection of the substrates used for growth of P. oleovorans. The largest monomer found in PHAs always contained as many C atoms as did the n-alkane used as a substrate. Monomers which were shorter by one or more C₂ units were also observed. Thus, for C-even substrates, only C-even monomers were found, the smallest being (R)-3-hydroxyhexanoate. For C-odd substrates, only C-odd monomers were found, with (R)-3-hydroxyheptanoate as the smallest monomer. 1-Alkenes were also incorporated into PHAs, albeit less efficiently and with lower yields than n-alkanes. These PHAs contained both saturated and unsaturated monomers, apparently because the 1-alkene substrates could be oxidized to carboxylic acids at either the saturated or the unsaturated ends. Up to 55% of the PHA monomers contained terminal double bonds when P. oleovorans was grown on 1-alkenes. The degree of unsaturation of PHAs could be modulated by varying the ratio of alkenes to alkanes in the growth medium. Since 1-alkenes were also shortened before being polymerized, as was the case for n-alkanes, copolymers which varied with respect to both monomer chain length and the percentage of terminal double bonds were formed during nitrogen-limited growth of P. oleovorans on 1-alkenes. Such polymers are expected to be useful for future chemical modifications.     

Separation and Identification of Fatty Acids

An improved method is described for separating saturated fatty acids by reversed-phase paper chromatography. The 2,4-dinitrophenylhydrazides prepared from saturated fatty acids from C₂ to C₂₂ are run upward on paper impregnated with tetralin, using 90% methanol—acetic acid—tetralin, 80% ethanol—acetic acid—tetralin, or 90% methanol—tetralin as the moving solvent. The simultaneous separations of all even-carbon acids from C₆ to C₂₂, all odd-carbon acids from C₇ to C₁₉, and also all odd- and even-carbon acids from C₇ to C₁₉ can be successfully performed by means of this paper chromatography. The method is useful for the detection of component saturated fatty acids in natural fats.