Production of γ-linolenic acid by Cunninghamella echinulata cultivated on glucose and orange peel

A newly isolated strain of Cunninghamella echinulata grown on glucose produced significant quantities of biomass and cellular lipids in media with high C/N ratio. The oil yield from glucose consumed increased after nitrogen exhaustion in the growth medium, but gamma-linolenic acid (GLA) content in cellular oil systematically decreased during the lipid accumulation process. When lipid accumulation was completed, GLA concentration in the cellular lipids progressively increased. The highest GLA production (720 mg/l) was achieved in medium with a C/N ratio equal to 163. C. echinulata was also able to grow on orange peel. The C/N ratio in the orange peel decreased from 50 to 26 during solid-state fermentation. Maximum oxygen uptake was observed during assimilation of reducing sugars, whereas a polygalacturonase activity was detected after reducing sugars had been exhausted. The maximum GLA production was 1.2-1.5 mg/g of fermented peel, calculated on a dry weight basis. After enrichment of the pulp with inorganic nitrogen and glucose, an increase in the production of oil and GLA was observed.     

Microthrix parvicella, a filamentous bacterium from activated sludge: growth on Tween 80 as carbon and energy source

Microthrix parvicella, cultivated in a medium with Tween 80 and Casamino acids, utilized only the oleic acid moiety of Tween 80 as carbon and energy source. The cell yield from Tween 80 was about 0.32 g dry weight of cells per g of Tween 80 consumed. As only the oleic acid moiety of Tween 80 was utilized, the cell yield from oleic acid was 1.3 g dry weight of cells per g oleic acid consumed. The amount of carbon produced as CO2 was less than 30% of the oleic acid-carbon and this low value was in agreement with the high cell yield. In batch culture M. parvicella stored large amounts of lipid material during the early growth phase. The fatty acids of the lipid globules were similar to the fatty acids supplied as carbon source. The percentage composition of the biomass changed to give C/N percentage ratios of about 15 during the early growth phase due to the high concentration of internal lipids and the low concentration of protein. The growth rate in batch culture was about 0.016 h-1 but was affected by the concentration of Casamino acids in the medium.     

Multiplication cellulaire et production lipidique en culture in vitro chez Taphrina insititiae et Taphrina pruni, parasites de Prunus domestica

Cellular Multiplication and Lipid Synthesis during in vitro Culture of Taphrina insititiae and Taphrina pruni, Parasites of Prunus domestica. Two Taphrina species were grown on “yeast extract/glucose” and harvested at regular intervals. Their growth was estimated by dry mycelial weight and cell nitrogen. Lipids were recovered and measured by weighing. Phospholipids, which form the major portion of polar lipids, were measured by phosphorus assay. Lipidic and nitrogenous products were studied with regard to the evolution of the cultures during the phase of active growth. The cells accumulated fats, but during the phase of autolysis, fat content decreased. Production of nitrogenous components was maximal during the autolytic phase. Phospholipids varied as nitrogenous and inversely to neutral lipids. There was apparently an antagonism between nitrogen assimilation and synthesis of neutral lipids. Different functions of neutral and polar lipids may be involved, so that the former act as a reserve material and the latter represent an essential structural cell constituent. Fatty acids were analysed by gas liquid chromatography at various culture periods. Fatty acids from polar as well as those from neutral lipids exhibited great variations with regard to culture evolution. The ratio insaturated/saturated fatty acids is greater in polar lipids than in neutral lipids. These variations are discussed with regard to their consequences for the function of cell membranes.     

Formation of prebiochemical compounds in models of the primitive earth's atmosphere. II: CH4 - H2S atmospheres.

In order to understand the role of sulfur in the primitive atmosphere, we have studied the action of a silent discharge on mixtures of CH4 and H2S at low pressure. The nature of the products formed in the gaseous phase, and the influence of several parameters, especially the H2S percentage, on the yield of the products are reported. The analysis of the products is carried out by gas liquid chromatography and infrared spectrometry. The formation of sulfur-containing compounds, such as thiols and sulfides, is reported. CS2 is formed in high yield (a few percent) in mixtures containing 40-50% of H2S, while the maximum concentration of thiols (i.e., CH3SH and C2H5SH) is reached with lower percentages of H2S. The formation of hydrocarbons decreases rapidly with increasing proportions of H2S. These results show the important inhibitor effect of H2S on the formation of hydrocarbons and the possibility of occurrence of many sulfur compounds in prebiological evolution.     

Lipid synthesis by Micrococcus freudenreichii in media containing unsaturated hydrocarbon's]

The growth and synthesis of lipids by thermotolerant bacteria Micrococcus freudenreichii K-219 were investigated in the mineral medium containing a mixture of unsaturated (I-) and saturated hydrocarbons. The bacteria utilized primarily I-alkenes. In lipids the predominant fractions were phospholipids (57%) and free fatty acids (20%). The content of waxes which were in significant quantities in n-alkane containing media (9%) was not higher than 0.3% dry matter upon utilization of I-alkenes. There was a certain correlation between carbon atoms of synthesized fatty acids and unsaturated hydrocarbons used. Bacteria utilizing I-alkenes showed no elevated unsaturation of cell lipids as compared to those assimilating n-alkanes. These data give evidence for different pathways of oxidation of alkenes and alkanes by the above microbial strain.     

花生四烯酸高产菌株的选育

本研究以一株能产生花生四烯酸的被孢霉菌为出发菌株,通过紫外线诱变筛选出一株高产花生四烯酸的突变株Ｍ１０,发酵试验结果表明：突变株Ｍ１０的每升培养液中干菌体得率为３１ｇ,油脂含量为８．３ｇ,而原菌株仅为２０．３ｇ和５．４ｇ,气相色谱分析结果Ｍ１０所产花生四烯酸的量占总脂的１０．０６％（０．８３ｇ／Ｌ培养液）。同时对Ｍ１０菌株的生长和发酵特性及发酵过程中菌丝体形态变化作了一定的探讨。     

Isolation and Characterization of a Thermotolerant Methanol-Utilizing Yeast

A yeast capable of growth on methanol as its sole carbon-energy source was isoalted from soil samples and identified as a strain of Hansenula polymorpha. A continuous enrichment culture at 37 C with a simple mineral salts medium was used to select this organism. The isolate, designated DL-1, has a maximal specific growth rate of 0.22 per h, at pH 4.5 to 5.5 and temperatures of 37 to 42 C, in simple mineral salts medium with methanol (0.5%), biotin, and thiamine. Growth occurred in a chemostat at temperatures up to 50 C, with strong growth at 45 C. The maximal growth yield of the yeast on methanol was 0.36 g of dry cell weight per g of methanol, and the yield on oxygen was 0.37 g of dry cell weight per g of O(2). Protein content of the isolate is 46%, and total nucleic acid content varies from 5.0 to 7.0% with increasing growth rate from 0.08 to 0.20 per h. The amino acid profile of this yeast protein indicates that it could serve as a good source of food protein. Feeding studies with rats show the yeast to have no toxic effects.     

Lipid and hydrocarbon compositions of a collection strain and a wild sample of the green microalga Botryococcus

Lipid composition and hydrocarbon structure of two colonial green algae of the genus Botryococcus, i.e., a museum strain and a field sample collected for the first time from Lake Shira (Khakasia, Siberia), have been compared. Polar lipids, diacylglycerols, alcohols, triacylglycerols, sterols, sterol esters, free fatty acids and hydrocarbons have been identified among lipids in the laboratory culture. The dominant fraction in the museum strain was formed by polar lipids (up to 50% of the lipids) made up of fatty acids from C₁₂ to C₂₄. Palmitic, oleic, C₁₆ - C₁₈ dienoic and trienoic acids were the main fatty acids of the museum strain. Aliphatic hydrocarbons were found in the lipid of the museum strain. However, these amounted maximally to about 1% of the dry biomass at the end of exponential growth phase. The qualitative and quantitative compositions of FAs and hydrocarbons of the museum strain of Botryococcus, (registered at the Cambridge collection as Botryococcus braunii Kutz No LB 807/1 Droop 1950 H-252) differed from those of the Botryococcus strain described in the literature as Botryococcus braunii. The Botryococcus sp. found in Lake Shira is characterized by a higher lipid content (<40% of the dry weight). Polar lipids, sterols, triacylglycerols, free fatty acids and hydrocarbons have been identified among lipids in the field sample. The main lipids in this sample were dienes and trienes (hydrocarbons <60% of total lipid). Monounsaturated and very long chain monounsaturated fatty acids, including C_28:1 and C_32:1 acids, were identified in the Botryococcus found in Lake Shira. The chemo-taxonomic criteria allow us to unequivocally characterize the organism collected from Lake Shira as Botryococcus braunii, race A.     

Conversion of sewage sludge into lipids by Lipomyces starkeyi for biodiesel production

The potential of accumulation of lipids by Lipomyces starkeyi when grown on sewage sludge was assessed. On a synthetic medium, accumulation of lipids strongly depended on the C/N ratio. The highest content of lipids was measured at a C/N-ratio of 150 with 68% lipids of the dry matter while at a C/N-ratio of 60 only 40% were accumulated. Within a pH range from 5.0 to 7.5 the highest lipid accumulation was found at pH 5.0 while the highest yield per litre was pH 6.5. Although sewage sludge had no inhibitory effects on growth or accumulation on L. starkeyi when added to synthetic medium, there was no significant growth on untreated sewage sludge. However, pretreatment of sludge by alkaline or acid hydrolysis, thermal or ultrasonic treatment lead to accumulation of lipids by L. starkeyi with highest values of 1 g L(-1) obtained with ultrasound pre-treatment. Based on the content of free fatty acids and phosphorus, lipids accumulated from sewage sludge could serve as a substrate for the production of biodiesel.     

Characterization of the fatty acid composition of Nannochloropsis salina as a determinant of biodiesel properties

Nannochloropsis salina was cultured batch-wise to evaluate the potential of the alga to produce biodiesel. The cells were harvested at the end of the exponential growth phase when the concentration was 18 x 10(6) cells/mL culture. The growth estimated as dry weight from this cell number was (3.8 +/- 0.7) mg/L. The lipid and triglyceride contents were 40% and 12% on a dry weight basis, respectively. The amount of the ratio triglycerides/total lipids was approximately 0.3. The composition of triglyceride fatty acid methyl esters (biodiesel) was analysed by gas-liquid chromatography and identified as: C14:0, C16:0, C16:1, C18:0, C18:1, C18:2, C18:3, C20:1, and C20:5. The ratio of unsaturated to saturated fatty acid contents was approximately 4.4. Additionally, the characterization of each individual fatty acid ester was discussed with regard to the fuel properties of biodiesel produced by the alga.     

Scenedesmus sp. NJ-1 isolated from Antarctica: a suitable renewable lipid source for biodiesel production

Microalgal lipids are promising alternative feedstocks for biodiesel production. Scenedesmus sp. NJ-1, an oil-rich freshwater microalga isolated from Antarctica, was identified to be a suitable candidate to produce biodiesel in this study. This strain could grow at temperatures ranging from 4 to 35?°C. With regular decrease in nitrate concentration in the medium, large quantities of triacylglycerols accumulated under batch culture conditions detected by thin layer chromatography and BODIPY 505/515 fluorescent staining. Scenedesmus sp. NJ-1 achieved the average biomass productivity of 0.105?g?l^?1?d^?1 (dry weight) and nearly the highest lipid content (35?% of dry cell weight) was reached at day 28 in the batch culture. Neutral lipids accounted for 78?% of total lipids, and C18:1 (n-9), C16:0 were the major fatty acids in total lipids, composing 37 and 20?% of total fatty acids of Scenedesmus sp. NJ-1 grown for 36?days, respectively. These results suggested that Scenedesmus sp. NJ-1 was a good source of microalgal oils for biodiesel production.     

Lipid composition of the nitrogen starved green alga Neochloris oleoabundans

Neochloris oleoabundans has been cultivated in mineral medium deficient in nitrogen. The yield of lipids was 35–54% of cell dry weight. Triglycerides comprised 80% of the total lipids. Aliphatic hydrocarbons, sterols, pigments, glycolipids and phospholipids comprised the remaining lipid fraction. Saturated, monounsaturated and diunsaturated octodecanoic acid represented approximately one-half of the total fatty acids.     

解糖热解纤维素菌F32降解未预处理秸秆及产纤维素酶特性分析

【目的】明确极端嗜热厌氧木质纤维素降解菌解糖热解纤维素菌F32代谢特征,并分析其产酶特性。【方法】使用细胞计数法绘制菌株的生长曲线,使用离子色谱及气相色谱进行产物和残糖量分析,以DNS法及对硝基苯酚法检测菌株胞外蛋白的酶活性。【结果】解糖热解纤维素菌F32在以葡萄糖、微晶纤维素和未经预处理小麦秸秆为碳源时生长状况优于解糖热解纤维素菌DSM 8903。在以葡萄糖为碳源进行培养时,与菌株DSM 8903相比,菌株F32具有产乳酸较多,而产氢气较少的特点。在以微晶纤维素和未经预处理小麦秸秆为碳源进行培养时,与菌株DSM 8903相比,菌株F32胞外蛋白具有较高的内切纤维素酶活性和木聚糖酶活性。【结论】解糖热解纤维素菌F32表现出较强的木质纤维素降解能力,其与DSM 8903的产物组成及胞外蛋白的酶活性具有明显差异。     

Metabolism of H2-CO2, methanol, and glucose by Butyribacterium methylotrophicum.

The fermentative metabolism of Butyribacterium methylotrophicum grown on either H2-CO2, methanol, glucose, or CO is described. The following reaction stoichiometries were obtained: 1.00 H2 + 0.52 CO2 leads to 0.22 acetate + 0.06 cell C; 1 methanol + 0.18 CO2 + 0.01 acetate leads to 0.24 butyrate + 0.29 cell C; and 1.00 glucose leads to 0.31 CO2 + 1.59 acetate + 0.21 butyrate + 0.13 H2 + 1.58 cell C. Cell yields of 1.7 g (dry weight) per mol of H2, 8.2 g (dry weight) per mol of methanol, 42.7 g (dry weight) per mol of glucose, and 3.0 g (dry weight) per mol of CO were obtained from linear plots of cell synthesis and substrate consumption. Doubling times of 9.0, 9.0, and 3 to 4 h were observed during batch growth on H2-CO2, methanol, and glucose, respectively. Indicative of a growth factor limitation, glucose fermentation in defined medium displayed a lower cell synthesis efficiency than when yeast extract (0.05%) was present. B. methylotrophicum fermentation displayed atypically high substrate/cell carbon synthesis conversion ratios for an anaerobe, as greater than 24% of the carbon was assimilated into cells during growth on methanol or glucose. The data indicate that B. methylotrophicum conserves carbon-bound electrons during growth on single-carbon or multicarbon substrates.     

The effect of temperature on growth,indole alkaloid accumulation and lipid composition of Catharanthus roseus cell suspension cultures

Cell suspension cultures of Catharanthus roseus were used to study the effect of temperature on plant cell lipids and indole alkaloid accumulation. Lowering the cultivation temperature increased the total fatty acid content per cell dry weight relative to that at higher temperatures, mainly because of increased accumulation of unsaturated C18 acids. In addition, an increase in the relative proportion of phosphatidylcholine and phosphatidylethanolamine was observed. Within individual lipids, the degree of unsaturation was increased and the mean fatty acid chain length decreased with reducing temperature. These changes may be interpreted as modifying the cell membrane fluidity to keep it optimal for growth and metabolism at each temperature. In spite of membrane modifications, the indole alkaloid content of the cells or the medium was not affected by temperature change.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - PC phosphatidylcholine - PE phosphatidylethanolamine - PI phosphatidylinositol - PS phosphatidylserine - PG phosphatidylglycerol - CL cardiolipin - DGD digalactosyldiglyceride - MGD monogalactosyldiglyceride - NL neutral lipids - DU degree of fatty acid unsaturation - TLC thin-layer chromatography - FID-GC flame ionisation detector-gas chromatography - dw dry weight     

Laccase-induced C–N coupling of substituted <Emphasis Type="Italic">p</Emphasis>-hydroquinones with <Emphasis Type="Italic">p</Emphasis>-aminobenzoic acid in comparison with known chemical routes

Magnetotactic bacteria are difficult to grow under defined conditions in culture, which has presented a major obstacle to commercial application of magnetosomes. We studied the relationships among the cell growth, magnetosome formation, dissolved oxygen concentration (DO), and the ability to supply oxygen to the cells. Mass culture of Magnetospirillum gryphiswaldense MSR-1 for the production of magnetosomes was established in a 42-L fermentor under the following conditions: (1) sterile air was the sole gas supplied in the fermentor, and DO could be regulated at any level below 10% saturation by cascading the stir rate to DO, (2) to resolve the paradoxical situation that the cell growth requires higher DO whereas magnetosome formation requires low DO below the detectable range of regular oxygen electrode, DO was controlled to optimal level using the change of cell growth rate, rather than reading from the highly sensitive oxygen electrode, as the signal for determining appropriate DO, and (3) timing and rate of supplying the substrates were determined by measuring cell density and Na-lactate concentration. Under these conditions, cell density (OD565) of strain MSR-1 reached 7.24 after 60-h culture in a 42-L fermentor, and cell yield (dry weight) was 2.17 g/L, the highest yield so far being reported. The yield of magnetosomes (dry weight) was 41.7 mg/L and 16.7 mg/L/day, which were 2.8 and 2.7 times higher than the previously reported yields.     

Hydrocarbon degradation by <Emphasis Type="Italic">Dietzia</Emphasis> sp. A14101 isolated from an oil reservoir model column

The hydrocarbon-degrading strain Dietzia sp. A14101 was isolated from an oil reservoir model column inoculated with oil-field bacteria. The column was continuously injected with nitrate (0.5 mM) from the start of water flooding, which lead to a gradual development of nitrate reduction in the column. Strain A14101 was able to utilize a range of aliphatic hydrocarbons as sole carbon and energy source during aerobic growth. Whole oil gas chromatography analysis of the crude oil phase from aerobic pure cultures showed that strain A14101 utilized the near complete range of aliphatic components and aromatic components toluene and xylene. Longer n-alkanes ≥C₁₇ were utilized simultaneously with the shorter C₁₀ and C₁₅. After 120 days aerobic incubation, the whole oil gas chromatography profile of the crude oil phase was similar to that of heavily biodegraded oils. Anaerobic degradation of hydrocarbons with nitrate was not observed. Nitrate reduction was, however, observed during anaerobic growth on propionate, which suggests that strain A14101 grows on fatty acids in the column rather than on hydrocarbons.     

Hydrocarbons in green and blue-green algae

Liquid column chromatography and thin-layer chromatography were used to determine the total content of hydrocarbons and gas chromatography was used to evaluate composition of hydrocarbons in green algae (Chlorella kessleri, C. vulgaris, Chlorella sp.,Scenedesmus acutus, S. acuminatus, S. obliquus) and the blue-green alga (Spirulina platensis) cultivated under autotrophic or heterotrophic conditions. InC. kessleri cultivated under heterotrophic conditions the content of hydrocarbons was found to be about 10^-2 % (per dry mass), whereas under autotrophic conditions it was about 10^-3 % (per dry mass). The highest content of hydrocarbons was detected in species of the genusScenedesmus cultivated autotrophically (10^-1 %). Heptadecane and hexacosane were found as major alkanes, 1-heptadecene was detected among alkenes.     

Membrane topography of anaerobic carbon monoxide oxidation in Rhodocyclus gelatinosus.

Rhodocyclus gelatinosus 1 grows anaerobically in the dark at the expense of carbon monoxide. Topographical studies with methyl viologen as the membrane probe indicated that CO oxidation and H2 production sites were on the cytoplasmic side of the cell membrane. Membrane-associated hydrogen gas production appeared to be a unidirectional reaction. In the dark, strain 1 whole cells oxidized CO and incorporated about 306 pmol of 32Pi into ATP per min per mg of protein. With CO as the sole energy-yielding substrate, cells grew with a low growth yield coefficient of 3.7 g (dry weight) of cells per mg of CO oxidized.     

Induction of T4 DNA ligase in a recombinant strain of Escherichia coli

The kinetics of cell growth and foreign protein production, as well as factors affecting protein stability, were studied and optimized in batch and fed-batch fermentations of a recombinant strain of Escherichia coli. The pL promoter from bacteriophage lambda under the control of a temperature-sensitive cl represser, with the entire construct integrated into the E. coli chromosome through the use of a defective bacteriophage lambda lysogen, was used to direct the synthesis of T4 DNA ligase. The biphasic fermentations consisted of a primary growth phase at 30 degrees C followed by an induction phase which was initiated by shifting the temperature to 42 degrees C. In the fed-batch fermentations, additional nutrients were added at the time of initiating induction. Maintenance of sufficiently high concentrations of the organic substrates (glucose and casamino acids) during the induction phase was required for continued cell growth at 42 degrees C. Such growth was essential for T4 DNA ligase formation and in vivo stability. Hence, fed-batch fermentations produced the highest yield of the foreign protein Commensurate with providing lower total amounts of substrates. In such cases, high cell densities (6 g dry wt/L) with substantial intracellular levels of T4 DNA ligase (4.6% total cellular protein, or 2.7% of the dry biomass) were achieved.