Stereospecific hydration of unsaturated fatty acids by bacteria

Three new 10-hydroxy fatty acids, all optically active, have been prepared by the anaerobic microbiological hydration of acis-9 double bond. Substrates that formed these new hydroxy fatty acids are linoleic, linolenic, and ricinoleic acids. The hydroxyl group has the D configuration and the methyl esters are levorotatory. Infrared, mass spectral, specific rotation and ultraviolet data on these compounds were determined. There was no migration of the unreated double bonds at C₁₂ and C₁₅ in linoleic or linolenic acids. The presence of a double bond in the 10-hydroxy fatty acids significantly increased the optical rotation of the methyl esters. The hydratase enzyme showed unusual specificity among Δ⁹ unsaturated acids. While it hydrates methylene interrupted and hydroxy unsaturated acids, it failed to hydrate either 9-decenoic, 12,13-epoxy- or 12-keto-cis-9-octadecenoic acids or sterculic acid. Presented at the AOCS Meeting, San Francisco, April 1969. No. Marketing and Nutrition Res. Div., ARS, USDA.     

Microbial conversions of alkanes and fatty acids

Alkanes are attacked readily by a wide variety of microorganisms. The most frequently encountered mode of oxidation is for one of the terminal methyl groups to be oxidized, through the alkanol, then the alkanal, to the corresponding fatty acid. Alkanes may be attacked subterminally also, and various ketones as well as the corresponding secondary alcohols can be produced. Subsequent degradation of these ketones occurs via introduction of oxygen into the chain to give a corresponding ester, which is then hydrolyzed to give a primary alkanol 2 carbon atoms shorter than the original alkane. The fatty acids arising by either route of oxidation, or by gratuitous introduction to the microbial system, may be oxidized by: (a) β-oxidation to give a number of acetyl-CoA units—intermediates of the process cannot be isolated from this pathway due to the tightly coupled nature of the substrates to the enzymes; (b) α-oxidation; or (c) oxidation at the other end of the molecule. In the latter case, ω- and ω—1-hydroxyfatty acids can be produced. ω-Hydroxyfatty acids are subsequently oxidized to give dicarboxylic acids, which can be isolated, sometimes in high yield, by use of appropriate microbial mutants lacking in certain of the key metabolizing enzymes. With some yeasts, the fatty acids, including the ω-hydroxyfatty acids, can be esterified to various sugars to give a series of glycolipids. In some cases, wax esters are formed between fatty acid and alkanol; these wax esters can include diunsaturated molecules having a close chemical similarity to those of sperm whale and jojoba oils. Various recent innovations have occurred using isolated enzyme systems which can be used in transesterification reactions to convert cheap triacylglycerols into high value added commodities such as cocoa butter.     

Synthesis of long-chain (E)-3-alkenoic acids by the Knoevenagel condensation of aliphatic aldehydes with malonic acid

Knoevenagel condensation of aliphatic aldehydes with malonic acid in equimolar ratio in triethylamine, which served the dual purpose of the solvent as well as the base, gave alkenoic acids in 80–88% yield as determined by acid values of the products and by gas-liquid chromatography with methyl heptadecanoate as the internal standard. The alkenoic acids were converted to methyl esters, purified by column chromatography and characterized by proton nuclear magnetic resonance, infrared and mass spectral analyses. The spectral data clearly established that the acids formed were (E)-3-alkenoic acids. The purified methyl esters were also subjected to the oxymercuration-demercuration reaction, and the mass spectra of the resulting methoxy esters confirmed the exclusive formation of 3-alkenoic acids.     

Microbial conversion of linoleic and linolenic acids to unsaturated hydroxy fatty acids

The conversion of oleic acid to 10-hydroxystearic acid with resting cells ofNocardia cholesterolicum (NRRL 5767) has been previously reported. These same microorganisms also convert linoleic and linolenic acids to 10-hydroxy-12c-octadecenoic and 10-hydroxy-12c,15c-octadecadienoic acids, respectively. The reaction occurs best at 35°C and a pH of 6.5. Under optimum conditions, 75–80% of the unsaturated fatty acid substrate is converted to the corresponding hydroxy acid. The hydroxy products were characterized by gas chromatography, gas chromatographymass spectrometry, nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. Other microorganisms that successfully converted these substrates include another strain ofNocardia cholesterolicum (NRRL 5768) andNocardia sp. (NRRL 5636). Presented at the 82nd Annual meeting of the American Oil Chemists’ Society, Chicago, IL, May 12–15, 1991.     

Microbial production of rare unsaturated fatty acids and alcohols

Aeromonas hydrophila N‐6, isolated from a soil sample, converted vegetable oils to several rare unsaturated fatty acids and alcohols accumulated inside the cells as a wax ester form. A. hydrophila N‐6 effectively decreased fatty acid chain lengths, and converted rapeseed, safflower and linseed oils into 7‐16:1 and 5‐14:1 fatty acids, 7,10‐16:2 and 5,8‐14:2 fatty acids, and 7,10,13‐16:3 fatty acids, respectively. Furthermore, A. hydrophila N‐6 reduced the resulting fatty acids to rare unsaturated fatty alcohols, such as 7‐16:1, 5‐14:1, 9,12‐18:2, 7,10‐16:2, 9,12,15‐18:3 and 7,10,13‐16:3. Such unsaturated fatty acids and alcohols are rarely found in natural oils. Because decreasing fatty acid carbon chain lengths from the carboxyl end and reducing unsaturated fatty acids to unsaturated fatty alcohols in industrially applicable scale are both difficult reactions to accomplish by chemical means, we suggest that A. hydrophila N‐6 may facilitate the introduction of new bioprocesses for producing rare unsaturated fatty acids and alcohols, especially fatty alcohols with more than two double bonds.     

Occurrence ofCis-6-hexadecenoic acid as the major component ofThunbergia alata seed oil

An unusual series of monoenoic fatty acids constitutes about 85% of the total acids in seed oil fromThunbergia alata. The major component in the oil,cis-6-hexadecenoic acid (82%), is accompanied by the homologous 4-tetradecenoic (ca. 0.2%) and 8-octadecenoic (1.8%) acids. Another homologous series is represented by 5-tetradecenoic (ca. 0.2%), 7-hexadecenoic (1.8%) and the familiar 9-octadecenoic (4.4%) acids. Traces (<0.1%) of three other acids, 6-tetradecenoic and 10- and 11-octadecenoic, are also present along with palmitic (5.8%), stearic (0.6%) and linoleic (2.2%) acids. Some of the monoenoic acids have not previously been known to occur in seed oils. Presented at the Fifth Great Lakes Regional Meeting of the American Chemical Society, Peoria, Illinois, 1971. No. Market. Nutr. Res. Div., ARS, USDA.     

Synthesis of ω9-tetracosynoic and ω9-octacosynoic acids as entries into tritiated metabolic precursors ofcis-9-tricosene andcis-9-heptacosene in the housefly

The syntheses of 15-tetracosynoic acid (ω9-tetracosynoic acid) and 19-octacosynoic acid (ω9-octacosynoic acid) are described. These alkynoic acids are to be tritiated to the corresponding alkenoic acids, which will be used as metabolic precursors of housefly pheromone components. The final step in each synthesis involved the coupling of 1-decyne to the lithio-salt of the appropriate ω-bromoacid. Homologation of dibromoalkanes was accomplished with triphasic catalytic displacement of bromide by cyanide ion. Oxidation of a bromo-alcohol to a bromoacid was performed in benzene with KMnO₄ and 18-crown-6 ether. Mention of a company name or product in this paper does not imply endorsement by the U.S. Department of Agriculture.     

Hydrazine-reduced linolenic acids as a source of C9, C12, and C15 dibasic acids

Anticipated reduction in cost of hydrazine, resulting from its increased production as a rocket fuel, suggests the need to reconsider this chemical as an industrial reactant for fats. Hydrazinc reduces the individual double bonds of linolenic acid (9,12,15-octadecatrienoic acid) nonselectively and without altering the position of residual unsaturation; thus the monoene fraction from hydrazine-reduced linolenic acid consists of an equimixture of the 9-, 12-, and 15-octadecenoate acids. Equal amounts of the C₉, C₁₂, and C₁₅ dibasic acids are derived from this fatty acid mixture by oxidative cleavage along with the corresponding monobasic acids. Kinetics of reactions, source of raw materials and reactants, and problems of processing and utilization of products are discussed. Presented before the Division of Organic Coatings and Plastics Chemistry, American Chemical Society, Washington, D. C., March, 1962. A laboratory of the No. Utiliz. Res. & Dev. Div. ARS, U.S.D.A.     

Early hydration of tricalcium silicate I. Kinetics of the hydration process and the stoichiometry of the hydration products

The initial hydration of C₃S in paste form at room temperature was studied. The process is initiated by a short lasting rapid hydration in which about 1 – 2% of C₃S is hydrated and a hydrate with low C/S and high H/S ratio is formed. After a subsequent induction period of 4 hours a renewed rapid hydration is observed in which a hydrate of constant stoichiometric composition, independent on the time of hydration is formed. This hydrate has a higher C/S and lower H/S ratio than the one formed initially. The liquid phase stays supersaturated with respect to calcium hydroxide for several hours after the induction period is terminated.     

协同水化制备水硬性材料及其水化产物的研究

按钢渣、矿渣和粉煤灰以5∶3∶2的比例组成复合废渣,在改性水玻璃等激发剂的协同作用下,制备得到的浆体28 d抗压强度高达53.56 MPa,凝结时间及安定性均合格。通过X射线衍射(XRD)分析、电子扫描电镜(SEM)形貌观察等对浆体中的水化产物进行分析,结果表明,在协同水化作用下,水化产物中存在网络状的水化硅酸钙(C-S-H)。     

CFBC ash hydration studies

Hydration studies on CFBC ashes have shown that the acetone technique to prevent hydration in stored samples is relatively effective, only allowing some slight degree of hydration over days in the presence of excess water. In the presence of large excesses of water sufficient to control temperature increases, the degree of bulk mixing has no effect on the degree of hydration, which is shown to be relatively slow at ambient conditions, taking hours to complete. Finally, the effect of salt addition on hydration has been shown to be negligible at the low levels typical of wastewater, but there may be effects at ion concentrations typical of seawater. This work suggests that experience gained from lime hydration should be applied with caution to studies on hydration of CFBC ashes.     

Mechanisms of cement hydration

The current state of knowledge of cement hydration mechanisms is reviewed, including the origin of the period of slow reaction in alite and cement, the nature of the acceleration period, the role of calcium sulfate in modifying the reaction rate of tricalcium aluminate, the interactions of silicates and aluminates, and the kinetics of the deceleration period. In addition, several remaining controversies or gaps in understanding are identified, such as the nature and influence on kinetics of an early surface hydrate, the mechanistic origin of the beginning of the acceleration period, the manner in which microscopic growth processes lead to the characteristic morphologies of hydration products at larger length scales, and the role played by diffusion in the deceleration period. The review concludes with some perspectives on research needs for the future.     

Steam hydration of CFBC ash and the effect of hydration conditions on reactivation

A detailed study has been carried out on how hydration methods and conditions influence the sulphur capture potential of ash from a 165 MWe circulating fluidized bed combustion boiler firing a petroleum coke and coal blend. Both bed ash and fly ash were hydrated with saturated steam at various saturation conditions for different periods of time. Samples of the hydrated residues were then analyzed for free lime and calcium hydroxide content after the hydration process. Some size fractions of the steam-hydrated samples and those hydrated with liquid water in previous work were re-sulphated for 90 min using synthetic flue gas in a thermogravimetric analyzer at 850 °C to investigate how reactivation conditions affect the final sulphur capture behaviour of the ash. This work confirms that either hydration method is effective for reactivating the bed ash fractions tested but not fly ash, which should either be re-injected directly or reactivated in some other manner to improve its sulphur capture potential.     

Two unsaturated 9R-hydroxy fatty acids from the cyanobacteriumAnabaena flos-aquae f. flos-aquae

(9R-10E,12Z,15Z)-9-Hydroxyotadecatrienoic acid and (9R,10E,12Z)-9-hydroxyoctadecadienoic acid were isolated from the nitrogen fixing cyanobacteriumAnabaena flosaquae. f. flos-aquae and characterized as the corresponding methyl esters. This is the first report of the natural occurrence of 9R-oxygenated fatty acids.     

Gel formation during early hydration

It is well know that gel formation and, in particular, gel-space ratio within cement paste has a considerable bearing on the strength and mechanical properties of concrete. This paper describes investigations into a method for monitoring the temporal changes in gel-space ratio within cement paste employing wide-band frequency response techniques.     

Early stage hydration of slag-cement

The early hydration characteristics of slag cements (blends of separately ground granulated blast furnace slags with portland cement) have been examined. Isothermal calorimetry, chemical shrinkage and compressive strength measurements were made. The kinetics of hydration have been treated; apparent activation energies determined for a slag cement were ～49 KJ/mole compared with ～44 KJ/mole for the portland cement used in the blends.     

Occurrence ofcis-5,cis-9-Hexacosadienoic andcis-5,cis-9,cis-19-Hexacosatrienoic acids in the marine spongeMicrociona prolifera

Fatty acid analysis of the total lipids from the marine spongeMicrociona prolifera by gas liquid chromatography on an EGSS-X column revealed two major peaks with equivalent chain length values of 27.08 and 27.74. Each of these components was isolated as a separate band by thin layer chromatography on AgNO₃-silicic acid. Characterization of the two unknowns by IR spectroscopy, NMR, hydrogenation, and gas liquid chromatography revealed that the unknown acids weren-26∶2 andn-26∶3 containing only nonmethylene interruptedcis-double bonds. Reductive ozonolysis identified the 26∶2 ascis-5,cis-9-hexacosadienoic acid and the 26∶3 ascis-5,cis-9,cis-19-hexacosatrienoic acid. Analysis of the fatty acid composition ofMicrociona total lipids showed 14% 26∶2 and 31% 36∶3. The neutral lipids, phosphatidylethanomaline, and phosphatidylserine all contained >41% C₂₆ acids; but only 4% C₂₆ was present in the phosphatidylcholine.