The Formation Of Glycerol Monodecanoate By A Dehydration Condensation Reaction: Increasing The Chemical Complexity Of Amphiphiles On The Early Earth

Dehydration/condensation reactions between organic molecules in the prebiotic environment increased the inventory and complexity of organic compounds available for self-assembly into primitive cellular organisms. As a model of such reactions and to demonstrate this principle, we have investigated the esterification reaction between glycerol and decanoic acid that forms glycerol monodecanoate (GMD). This amphiphile enhances robustness of self-assembled membranous structures of carboxylic acids to the potentially disruptive effects of pH, divalent cation binding and osmotic stress. Experimental variables included temperature, water activity and hydrolysis of the resulting ester product, providing insights into the environmental conditions that would favor the formation and stability of this more evolved amphiphile. At temperatures exceeding 50 ^∘C, the ester product formed even in the presence of bulk water, suggesting that the reaction occurs at the liquid interface of the two reactants and that the products segregate in the two immiscible layers, thereby reducing hydrolytic back reactions. This implies that esterification reactions were likely to be common in the prebiotic environment as reactants underwent cycles of wetting and drying on rare early landmasses at elevated temperatures     

Comparison of growth and lipid content in three <Emphasis Type="Italic">Botryococcus braunii</Emphasis> strains

The growth and lipid content of three Botryococcus braunii strains from China (CHN), United Kingdom (UK) and Japan (JAP) were compared at three temperatures (20, 25 and 30 ^∘C), three irradiances (60, 100 and 300 W m⁻²) and four salinities (0, 0.15, 0.25, and 0.5 M NaCl) for 30 days, respectively. In the temperature trial, the UK strain and JAP strain grew faster at 25 ^∘C than at other temperatures, while the CHN strain performed equally well at 20 and 25 ^∘C. The JAP strain grew slowest among the three strains at all temperatures, whereas the growth rate of the CHN and UK strains was similar at all temperatures except at 20 ^∘C. The UK strain contained the highest lipid content, but the CHN strain had the lowest lipid content at most temperatures. In the light trial, the highest growth rate was found in the UK strain and the lowest growth rate was observed in the JAP strain at most irradiances. The UK and JAP strains contained more lipids than the CHN strain at 60 and 100 W m⁻², but the lipid content was not significantly different among the three strains at 300 W m⁻². In the salinity trial, both the CHN and UK strains grew faster than the JAP strain at all salinities, but the growth rate between the CHN and UK strains was not different. However, the CHN strain had the lowest lipid content whereas the UK strain produced the highest lipids at most salinities. Our results indicate that the CHN strain and the UK strain grow faster than the JAP strain, but the UK and JAP strains produce more lipids than the CHN strain. The UK strain should be considered as a potential B. braunii strain for the exploitation of renewable energy.     

Effects of temperature and salinity on the growth of Gracilaria verrucosa and G. chorda, with the Potential for mariculture in Korea

Effects of temperature and salinity on the growth of the two agarophytes, Gracilaria verrucosa (Hudson) Papenfuss and Gracilaria chorda Holmes were examined in Korea. Both species grew over a wide range of temperatures (10–30 ^∘C) and salinities (5–35‰), and grew well at 17–30 ^∘C and a salinity of 15–30‰. In culture, G. verrucosa grew faster than G. chorda and their maximum growth rates were 4.95% day⁻¹ (30 ^∘C, 25‰) and 4.47% day⁻¹ (at 25 ^∘C, 25‰), respectively. In the field population the maximum growth and fertility of G. chorda were observed in summer. The growth rate of G. verrucosa was slightly higher than that of G. chorda for 2 weeks on the cultivation rope and in culture but it was much lower after being contaminated with epiphytes. The biomass of the epiphytes was 0.82 g dry wt. per host plant in G. verrucosa and 0.001 g in G. chorda. G. chorda exhibited resistance to epiphytism and grew 7 times in length and the dry weight increased 15 times after 55 days. In conclusion, G. chorda appears to be a good agarophyte with a fast growth rate and resistance to epiphytesm, and compared with G. verrucosa, has good potential for commercial cultivation.     

Developmental Studies in Porphyra Vietnamensis: a High-Temperature Resistant Species from the Indian Coast

Porphyra vietnamensis Tanaka & Pham-Hoang Ho (Bangiales, Rhodophyta) is a tropical seaweed collected from the west coast of India. Thalli of the blade phase are found growing only during the rainy season between July and September. They grow on rocky intertidal or subtidal substrata or as epiphytes on other seaweeds such as Enteromorpha flexuosa and Chaetomorpha media. The gametophytic thallus is monostromatic and covered with spines at the base. The species is monoecious. Male gametangia are found in patches that are distributed in the upper part of the thallus. Archeospores are found at the thallus margins and give rise to the blade phase after one week of germination even at 30 ^∘ C. Zygotospores germinated at 25 ^∘ C into conchocelis within three days from the date of their inoculation. Conchospores were released at 30 ^∘ C. The young blades grew at 32 ^∘ C in the laboratory.     

Hydrolysis of cyclic poly(ethylene terephthalate) trimers by a carboxylesterase from Thermobifida fusca KW3

We have identified a carboxylesterase produced in liquid cultures of the thermophilic actinomycete Thermobifida fusca KW3 that were supplemented with poly(ethylene terephthalate) fibers. The enzyme hydrolyzed highly hydrophobic, synthetic cyclic poly(ethylene terephthalate) trimers with an optimal activity at 60°C and a pH of 6. V _max and K _m values for the hydrolysis were 9.3 μmol⁻¹ min⁻¹ mg⁻¹ and 0.5 mM, respectively. The esterase showed high specificity towards short and middle chain-length fatty acyl esters of p-nitrophenol. The enzyme retained 37% of its activity after 96 h of incubation at 50°C and a pH of 8. Enzyme inhibition studies and analysis of substitution mutants of the carboxylesterase revealed the typical catalytic mechanism of a serine hydrolase with a catalytic triad composed of serine, glutamic acid, and histidine.     

Thermoregulatory changes in the cold induced by physical training in humans

It has previously been demonstrated that metabolic heat production (M˙) during cold exposure at rest was related to maximal oxygen uptake (O_2max). Consequently, an increase in O_2max could allow an increase M˙ in the cold. The aim of the present study was therefore to test this hypothesis. Eight male volunteers undertook interval training (periods of 25% V˙O_2max of 30-s duration and 110% V˙O_2max of 60-s duration until exhaustion, five times a week over 8 weeks) to increase V˙O_2max. Both before and after this physical training, they were subjected to a 10^∘, 5^∘ and 1^∘C 2-h cold air test in a climatic chamber. During the cold exposure, rectal temperature (T _re), tympanic temperature (T _ty), mean skin temperature () and M˙ were measured as well as the time to onset of shivering (t) and body temperatures () at t. The results showed that physical training involved an increase in O_2max (14%–15%, P < 0.05). During the cold exposure, T _re was higher after training both at 10^∘,5^∘ and 1^∘C (P < 0.05) whereas were not significantly changed. However, an increase in the sensitivity of the thermoregulatory system was attested by a decreased t at higher These slight physiological changes found after training were not related to the increases in V˙O_2max. In conclusion, this study demonstrated that interval training induced slight thermoregulatory changes unrelated to changes in V˙O_2max and it suggested that M˙ during cold exposure could be related mainly to the level of V˙O_2max observed before training, since increases in V˙O_2max did not modify M˙. Accepted: 8 April 1998     

Synthesis of glyceryl ferulate by immobilized ferulic acid esterase

Glyceryl ferulate was synthesized by the condensation of ferulic acid with glycerol using Pectinase PL “Amano” from Aspergillus niger, which contained ferulic acid esterase, to improve the water-solubility of ferulic acid. The optimum reaction medium was glycerol/0.1 M acetate buffer, pH 4.0, (98:2 v/v). The enzyme immobilized onto Chitopearl BCW3003 exhibited the highest activity among the those immobilized onto various kinds of Chitopearl BCW resins. The optimum temperature for the immobilized enzyme was 50°C, and it could be reused at least five times without a significant loss in activity for the synthesis of glyceryl ferulate in batch reaction. Storage of the reaction mixture at 25°C improved the molar fraction of glyceryl ferulate relative to the dissolved ferulic residues.     

Recent Fluctuations in Distribution and Biomass of Cold and Warm Temperature Species of Laminarialean Algae at Cape Ohma, Northern Honshu, Japan

The Cape Ohma region of Shimokita Peninsula, the northernmost point of Honshu Island, Japan, is subject to both the warm Tsugaru Current and the cold Kurile Current. As a result, the Laminarialean flora includes both cold temperature species (Laminaria japonica Areschoug, Kjellmaniella crassifolia Miyabe and Costaria costata (C. Agardh) Saunders) and warm temperature species (Undaria peterseniana (Kjellman) Okamura, Ecklonia stolonifera Okamura), as well as Undaria pinnatifida (Yendo) Okamura, which is distributed in both waters. The frequency of occurrence (as a measure of distribution) and the biomass of these species were recorded in June 1976 (at 50 points in depths between 8–30 m), July 1988 (192 points, 2.5–25 m) and July 2001 (78 points, 2.5–25 m). Comparison of these data revealed a decrease in cold temperature species and an increase in warm temperature species from 1976 or 1988 to 2001. Long-term data of seawater temperature measured at 5 m depth near the study site showed that mean temperatures in the middle of winter (late January to February) in 1989–2000 were 0.9–1.1 ^∘C higher than those in 1980–1988. Higher seawater temperatures in the last decade appear to have affected the frequency of occurrence and biomass of the Laminarialean species along the coasts of Cape Ohma. This result supported our previous conclusion that 1 ^∘C higher mean seawater temperature in late January caused a decrease in the biomass of L. japonica (by ca. 64%) along the same coast.     

Combined influence of light and temperature on growth rates of <Emphasis Type="Italic">Nannochloropsis oceanica</Emphasis>: linking cellular responses to large-scale biomass production

The interaction effects between irradiance and temperature on growth rates ofNannochloropsis oceanicawere determined in both laboratory cultures and large-scale tubular photobioreactors. Growth responses were investigated in 48 batch cultures subjected to crossing light/temperature gradients ranging from 34–80μmol photons m⁻²s⁻¹and 14.5–35.7^∘C respectively. Comparisons were made to growth responses observed in production systems (200L biofences) operated in climate-regulated greenhouses with controlled temperature and artificial light gradients. Cellular responses showed increasing specific growth rates as a function of temperature, with a peak at 25–29^∘C, after which the growth became increasingly unstable. The optimum temperature for growth increased with higher light intensities up to approximately 28^∘C at 80μmol photons m⁻²s⁻¹. At low light intensities the specific growth rate was less affected by temperature. The maximum daily production measured in the biofence systems increased proportionally with irradiation and reached approximately 0.7gL⁻¹d⁻¹at 1030μmol photons m⁻²s⁻¹average daily radiation for a culture temperature of 24^∘C. This corresponds to a daily yield of 140g per day in a 200L biofence system. When specific growth rates for the biofence cultures were measured at different densities and plotted against temperature, results showed a peak with the 24^∘C temperature treatment. This peak became less pronounced as the density increased in the cultures. This is consistent with the laboratory results; increasing cell density in the biofence cultures resulted in less average light cell⁻¹, which produced the same temperature dependent response as seen by reducing the external irradiance exposure for the dilute laboratory cultures.     

Seasonal Pattern of Reproduction Of Hizikia Fusiformis (Sargassaceae, Phaeophyta) from Nanao Island, Shantou, China

The maturation pattern of sexual reproduction in Hizikia fusiformis (Harvey) Okamura (Sargassaceae, Phaeaophyta) was examined in 2003 at Yunao Bay, Nanao Island, Shantou, China. Maturation began in mid-April (seawater temperature 19–21 ^∘C), reached the peak in mid-May (maturation rate ca. 70%, and seawater temperature 23.5–25 ^∘C) and finished in late-June (seawater temperature 27.5–30 ^∘C). The Hizikia plants continued to gain the length from the beginning of maturation season to reach a maximum mean length of 34.8 cm in mid-May, after which the mean length was reduced drastically due to the senescence and rupture of the larger plants in size. The major portion of the mature plants belonged to the larger plants between April and May, but to the smaller ones in June. It is suggested that the plant must achieve a critical size before reproductive maturation occurred. There was a positive relationship between the number of receptacles (NR), as well as the reproductive allocation (RA), and the plant size of Hizikia population, with the recorded maximum values of NR and RA being 1220 and 64.3% respectively, for a single plant.     

A thermostable lipolytic enzyme from a thermophilic Bacillus sp.: Purification and characterization

A thermophilic Bacillus sp. was isolated that secreted an extracellular, thermostable lipolytic enzyme. The enzyme was purified to 58 folds with a specific activity of 9730 units/mg of protein and yield of 10% activity by ammonium sulphate precipitation, Phenyl Sepharose chromatography, gel-permeation followed by Q Sepharose chromatography. The relative molecular mass of the protein was determined to be 61 kDa by SDS-PAGE and approximately 60 kDa by gel permeation chromatography. The enzyme showed optimal activity at 60–65 ^∘C and retained 100% activity after incubation at 60 ^∘C and pH 8.0 for 1 h. The optimum pH was determined to be 8.5. It exhibited 50% of its original activity after 65 min incubation at 70 ^∘C and 23 min incubation at 80 ^∘C. Catalytic function of lipase was activated by Mg⁺⁺ (10 mM), while mercury (10 mM) inactivated the enzyme completely. No effect on enzyme activity was observed with trypsin and chymotrypsin treatment, while 50% inhibition was observed with thermolysin. It was demonstrated that PMSF, SDS, DTT, EDTA, DEPC, βME (100 mM each) and eserine (10 mM) inhibited the activity of the lipolytic enzyme. With p-nitrophenyl laurate as a substrate, the enzyme exhibited a K _m and V _max of 0.5 mM and 0.139 μM/min/ml. The enzyme showed preference for short chain triacylglycerol and hydrolyzes triolein at all positions. In contrast to other thermostable Bacillus lipases, this enzyme has very low content of hydrophobic amino acids (22.58 %). Immunological studies showed that the active site and antigen-binding site of enzyme do not overlap.     

The effect of indole-3-Acetic acid on ethylene formation in wheat seedlings

Isoperoxidase B 1 isolated from winter wheat (Triticum aestivum L., cv. Jubilar) seedlings was shown to catalyze ethylene formation from α-keto, γ-methylmercaptobutyric acid (KMBA). In the presence of Mn²⁺, indole-3-acetic acid (IAA), andp-coumaric acid, the kinetics by isoperoxidase B 1 catalyzed conversion of KMBA into ethylene and other products was similar to that of IAA oxidation. The reaction rate was therefore controlled by IAA through its electrondonating properties. Exogenous IAA induced ethylene formation in the segments of etiolated wheat coleoptiles. IAA-induced ethylene production was enhanced by L-methionine and mitomycin C. Aminoethoxy-analogue of rhizobitoxine, ferulic acid, sodium benzoate, cycloheximide and actinomyoin D exhibited significant inhibitory effects. These data indicate that the overall reaction mechanism in coleoptile segments involves RNA and protein synthesis. The site of IAA action is not specific; 2,4-dichlorophenoxyacetic, α-naphthylacetic and indole-3-butyric acids, respectively, possessed comparable inductive effect as IAA. Indole-3-propionic acid, indole, L-tryptophan and glucobrassicin had only low inductive efficiency, and moreover indole and L-tryptophan slowed down IAA-induced ethylene formation.     

Application of several types of substrates to ficin-catalyzed peptide synthesis

Summary. The capability of ficin, a cystine protease, to form peptide bonds was investigated using several types of N-Boc-amino acid phenyl and naphthyl esters as acyl donor components. Enzyme-catalyzed peptide synthesis was carried out under optimized reaction conditions of pH, acyl acceptor concentration and selection of the best yield organic solvent. It used a condensation of N-Boc-Ala-OpGu and Ala-pNA as a model reaction. The products were obtained in 72–96% yield using 10 different substrates, within a few minutes of reaction time. Authors’ address: Prof. Haruo Sekizaki, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan     

Identification and Kinetic Characterization of HtDTC, The Mitochondrial Dicarboxylate–Tricarboxylate Carrier of Jerusalem Artichoke Tubers

Jerusalem artichoke (Helianthus tuberosus L.) tubers were reported to be tolerant to cold and freezing. The aim of this study was to perform a kinetic characterization of the mitochondrial dicarboxylate–tricarboxylate carrier (HtDTC) and to assess a possible involvement of this carrier in the cold tolerance of tubers. The HtDTC was purified from isolated mitochondria by sequential chromatography on hydroxylapatite/celite and Matrex Gel Orange A. SDS gel electrophoresis of the purified fraction showed a single polypeptide band with an apparent molecular mass of 31.6 kDa. A polyclonal antibody raised against the tobacco DTC cross-reacted with the purified protein on Western blot analysis. In gel trypsin, digestion of the purified HtDTC yielded peptides that exhibited strong amino acid sequence similarity to previously identified plant DTCs. Furthermore, using degenerate primers, a portion of the Htdtc cDNA was amplified and sequenced; this cDNA encoded for a protein with high sequence similarity to known plant homolog DTCs. When reconstituted in liposomes loaded with dicarboxylate (2-oxoglutarate, malate, malonate, succinate, and maleate) or tricarboxylate anions (citrate, trans-aconitate, and isocitrate), the purified HtDTC transported all these anions in exchange with external [¹⁴C]2-oxoglutarate. A kinetic characterization of HtDTC was performed: (a) the half-saturation constant K _m and the V _max at 25^∘C of the 2-oxoglutarate/2-oxoglutarate exchange by reconstituted HtDTC were found to be 360 μM and 10.9 μmol/(min mg protein), respectively; (b) the activation energy E _a of the succinate/2-oxoglutarate exchange by the reconstituted HtDTC was found to be 50.7 kJ/mol constant between −5 and 35^∘C. Similarly, the activation energy E _a of succinate respiration of isolated Jerusalem artichoke mitochondria, measured between −2 and 35^∘C, was shown to be constant (65.3 kJ/mol). The physiological relevance of kinetic properties and temperature dependence of transport activities of HtDTC is discussed with respect to the cold tolerance ability of Jerusalem artichoke tubers.     

Peptide Thioester Synthesis via an Auxiliary-Mediated N–S Acyl Shift Reaction in Solution

The 4,5-dimethoxy-2-mercaptobenzyl (Dmmb) group attached to a main chain amide in a peptide is easily transformed into an S-peptide via an intramolecular N–S acyl shift reaction under acidic conditions, and the S-peptide produces a peptide thioester through an intermolecular thiol–thioester exchange reaction. In order to develop a method for efficiently preparing peptide thioesters based on the N–S acyl shift reaction, the factors involved in this process were analyzed in detail. The general features of the transformation at the Dmmb group attached amide bond in a trifluoroacetic acid (TFA) solution and the generation of a peptide thioester were examined by ¹³C-NMR spectral measurements, reversed-phase (RP) HPLC analyses, mass measurements, and amino acid analyses. The methoxy group of the Dmmb group was not essential for the N–S acyl shift reaction, but played a role in stabilizing the thioester form. The addition of water to the TFA solution accelerated the N–S acyl shift reaction mediated by the Dmmb group and also suppressed the acid-catalyzed cleavage of the Dmmb group. A peptide thioester was produced from the S-peptide via an intermolecular thiol–thioester exchange reaction with minimal epimerization of the amino acid residue that constituted the thioester bond. Undesirable side reactions, such as the hydrolysis of the thioester bond and an S–N acyl shift reaction occurred during the synthetic process, which is a subject of further investigation.     

The γ-irradiation of aqueous solutions of urea. Implications for chemical evolution

0.05 mole dm^–3, O₂-free aqueous solutions of urea were studies after receiving various doses of⁶⁰Co gamma rays (0.14–600 kGy). Urea was found to be relatively stable under radiation; its radiation chemical yield of decomposition was 0.47. Hydrogen (G=0.50), carbon dioxide (G=0.44), ammonia (G=0.22), oxalic acid (G=0.0054), malonic acid (G=0.000064) and three unidentified oligomers were found to be the main radiolytic products. The origin of these products is explained by free radical reactions initiated by the transients from water radiolysis (H·,·OH,e _aq ^– ).     

Effects of Environmental Factors and Metal Ions on Growth of the Red Alga Gracilaria Chorda Holmes (Gracilariales, Rhodophyta)

Gracilaria is a potentially valuable source of marine biopolymers such as proteins and polysaccharides. In order to select suitable culture conditions, growth and tolerance of Gracilaria chorda Holmes from Shikoku Island in southwest Japan were investigated under variations of temperature (5–30 ^∘C), photon irradiance (20–120 μmol photons m⁻² s⁻¹), and photoperiod (12:12 h, 14:10 h light:dark regime) in a unialgal culture. Gracilaria chorda showed wide tolerances for all factors investigated, which is characteristic of eurythermal species. Maximum growth was observed at 18–24 ^∘C. The optimum photon irradiance for the algal growth was 60–120 μmol photons m⁻²s⁻¹. Instead of using ordinary sea salt (NaCl) to prepare artificial seawater, ultra pure salt was adopted. Gracilaria chorda grew faster in artificial seawater made with ultra-pure salt than that made with ordinary sea salt, probably because the former medium was clear, while the latter was milky. Effects of some metal ions on the growth were tested with artificial seawater. Iron ions affected algal growth, but cobalt ions did not. This study enables us to determine suitable culture conditions for G. chorda. A scaled-up 30 l culture of G. chorda under such conditions was successful.     

Theoretical description of hydrogen bonding in oxalic acid dimer and trimer based on the combined extended-transition-state energy decomposition analysis and natural orbitals for chemical valence (ETS-NOCV)

In the present study we have analyzed hydrogen bonding in dimer and trimer of oxalic acid, based on a recently proposed charge and energy decomposition scheme (ETS-NOCV). In the case of a dimer, two conformations, α and β, were considered. The deformation density contributions originating from NOCV’s revealed that the formation of hydrogen bonding is associated with the electronic charge deformation in both the σ—(Δρ_σ) and π-networks (Δρ_π). It was demonstrated that σ-donation is realized by electron transfer from the lone pair of oxygen on one monomer into the empty r_{H - O}^* \rho_{H - O}^* orbital of the second oxalic acid fragment. In addition, a covalent contribution is observed by the density transfer from hydrogen of H-O group in one oxalic acid monomer to the oxygen atom of the second fragment. The resonance assisted component (Δρ_π), is based on the transfer of electron density from the π—orbital localized on the oxygen of OH on one oxalic acid monomer to the oxygen atom of the other fragment. ETS-NOCV allowed to conclude that the σ(O---HO) component is roughly eight times as important as π (RAHB) contribution in terms of energetic estimation. The electrostatic factor (ΔE_elstat) is equally as important as orbital interaction term (ΔE_orb). Finally, comparing β-dimer of oxalic acid with trimer we found practically no difference concerning each of the O---HO bonds, neither qualitative nor quantitative.     

Combined effects of an oxidative enzyme and dissolved humic substances on 13C-labelled 2,4-D herbicide as revealed by high-resolution 13C NMR spectroscopy

Phenoxyalkanoic acids are a widely used class of herbicides. This work employed high-resolution ¹³C NMR to study the structural changes induced by humic substances and horseradish perodixase on 2,4-dichorophenoxyacetic acid (2,4-D) ¹³C-labelled in the side chain. NMR spectra showed that humic substances chemically catalyze abiotic splitting of [¹³C]2,4-D into 2,4-dichlorophenol and [¹³C]acetic acid at pH 7 but not at pH 4.7. Peroxidase did not catalyze the oxidative degradation of [¹³C]2,4-D at any pH tested and inhibited the effect of humic substances. Catalytic degradation by humic substances was attributed to free-radical reactions enhanced by the stereochemical contribution of large conformational structures formed by heterogeneous humic molecules at neutral pHs. Inhibition of 2,4-D degradation when humic substances were combined with peroxidase was explained by modification of both chemical and conformational humic structure due to peroxidase-promoted oxidative cross-coupling among humic molecules. Our findings show for the first time that the abiotic degradation of 2,4-D is catalyzed by dissolved humic substances at neutral pH. Journal of Industrial Microbiology & Biotechnology (2001) 26, 70–76. Received 09 February 2000/ Accepted in revised form 22 May 2000     

Lipid Formation by Aqueous Fischer-Tropsch-Type Synthesis over a Temperature Range of 100 to 400 °C

The formation of lipid compounds during anaqueous Fischer-Tropsch-type reaction was studied withsolutions of oxalic acid as the carbon and hydrogensource. The reactions were conducted in stainlesssteel vessels by heating the oxalic acid solution atdiscrete temperatures from 100 to 400 °C, atintervals of 50 °C for two days each. Themaximum lipid yield, especially for oxygenatedcompounds, is in the window of 150–250 °C. At atemperature of 100 °C only a trace amount oflipids was detected. At temperatures above150 °C the lipid components ranged from C₁₂to >C₃₃ and included n-alkanols, n-alkanoic acids, n-alkyl formates, n-alkanals, n-alkanones, n-alkanes, andn-alkenes, all with essentially no carbon numberpreference. The n-alkanes increased inconcentration over the oxygenated compounds attemperatures of 200 °C and above, with a slightreduction in their carbon number ranges due tocracking. It was also noted that the n-alkanoicacids increased while n-alkanols decreased withincreasing temperature above 200 °C. Attemperatures above 300 °C synthesis competeswith cracking and reforming reactions. At 400 °Csignificant cracking was observed and polynucleararomatic hydrocarbons and their alkylated homologswere detected. The results of this work suggest thatthe formation of lipid compounds by aqueous FTTreactions proceeds by insertion of a CO group at theterminal end of a carboxylic acid functionality toform n-oxoalkanoic acids, followed by reductionto n-alkanoic acids, to n-alkanals, thento n-alkanols. The n-alkenes areintermediate homologs for n-alkan-2-ones andn-alkanes. This proposed mechanism for aqueousFTT synthesis differs from the surface-catalyzedstepwise FT process (i.e., gaseous) of polymerization of methylene reported in the literature.