产油嗜碱绿球藻MC-1的烟气适应性

为了降低微藻产油成本和减少温室气体的排放,利用煤炭烟气培养一株具有pH快速漂移和高碱适应特性的产油微藻Chlorococcum alkaliphilus MC-1.首先于15L光生物反应器中分三组(空白组、CO2组和烟气组)进行小体积培养实验,然后在24 m2开放式跑道池中进行放大培养,研究了微藻MC-1对烟气培养的适应性.结果表明,在光生物反应器培养实验中,烟气组的最高生物量浓度、生长速率、藻体总脂含量和CO2固定速率分别为:(1.02±0.07) g/L、(0.12±0.02) g/(L·d)、(37.84±0.58)％和(0.20±0.02) g/(L·d),比CO2组分别提高了36％、33.33％、15.34％和33.33％.在开放式跑道池培养实验中,烟气与纯CO2的培养效果相似,烟气培养下的最高生物量浓度、生长速率、藻体总脂含量和CO2固定速率分别为:147.40 g/m2、14.73 g/(m2·d)、35.72％和24.01 g/(m2·d);烟气培养产出的藻粉中有毒重金属Pb、As、Cd和Cr的含量均低于国家限量标准.实验同时测定了烟气培养下藻液对烟气中CO2、NO和SO2的吸收效果,结果显示,在光生物反应器和开放式跑道池培养中此三种气体的平均吸收率均高于以往研究结果.上述结果说明,该藻能适应烟气培养条件,耦合微藻MC-1产油与烟气减排的室外放大培养是可行的.     

Liquid residence time distributions in immobilized cell bioreactors

Previous work has demonstrated that high ethanol productivities can be achieved using yeast or bacterial cells adsorbed onto the surface of ion exchange resin in vertical packed bed bioreactors. The present work quantitatively characterizes the overall degree of backmixing in such reactors at two scales of operation: 2.0 and 8.0 L. Stimulus-response experiments, using two solvents (2,3-butanediol and 2-ethoxyethanol) as tracers, were performed to measure the liquid phase residence time distribution (RTD) during continuous ethanol fermentations using the yeast Saccharomyces cerevisiae and the bacterium Zymomonas mobilis at the 2-L scale, and with S. cerevisiae at the 8-L scale. In order to separately determine the effects of liquid flow rate and gas evolution on the degree of mixing, stimulus-response experiments were also performed in the systems without microbial cells present. The evolution of CO(2) was found to dramatically increase the extent of mixing; however, the tanks-in-series model for non-ideal flow represented the systems adequately. The packed beds were equivalent to over 70 tanks-in-series during abiotic operation while during fermentations, with similar liquid flow rates, they ranged in equivalence from 35 to 15 tanks-in-series. This increased knowledge of the overall degree of mixing in packed bed, immobilized cell bioreactors will allow for more accurate kinetic modelling and efficient scale up of the process.     

The production of L-serine with a methylotrophic microorganism using the L-serine pathway and coupling with an L-tryptophan-producing process

The cultural conditions for the production of enhanced formation of L-serine (up to 7 g/L) are described with the methylotrophic bacterium Pseudomonas 3 ab (DSM 672). The batch process is divided into three parts: (1) the biomass production phase, (2) substrate limitation period, and (3) L-serine accumulation phase. The initial specific production rate of q(p) = 0.1 g L-serine/g dry wt/h is based on the inhibition of the L-serine pathway. This is accomplished by high precursor concentrations (glycine) and a pH shift to pH 8.5. The enzymatic background is discussed. Furthermore, a coupling of the L-serine process with a L-tryptophan-producing process is demonstrated.     

一株表面活性剂产生菌的筛选及其特性研究

从氧化沟含油污水中分离得到1株能产生物表面活性剂菌株S6(Pseudomonas sp.),经生理生化实验和16SrDNA序列分析鉴定,S6为铜绿假单胞菌。红外光谱分析得知S6在代谢过程中能够产生糖脂类表面活性物质。其临界胶束浓度(CMC)为50mg/L,可将水的表面张力由72mN/m降到33.9mN/m。发酵液的表面张力和排油直径的测定结果显示发酵液在不同的盐度、pH和溶解氧量条件下,具有较稳定的表面活性。通过正交实验确定了优化培养基条件为葡萄糖10g、尿素5g、磷酸二氢钾1g、微量元素液2mL、pH8.0、水1000mL;S6在优化培养基中合成生物表面活性剂的产量为0.173g/L。     

Variations in the oxidation-reduction behavior of liganded species of Pseudomonas cytochrome oxidase

In an effort to determine the steady-state redox properties of Pseudomonas aeruginosa cytochrome cd1, changes in absorption spectra after the addition of excess reductant (ascorbate, ferrous ethylenediaminetetraacetic acid) were monitored for degassed unliganded enzyme and samples in the presence of CO and CN- at pH 6.0, 8.0, or 10.0. Plots of [c2+]/[c3+] vs. [d2+]/[d3+] indicate that a "pseudoequilibrium" was reached for all samples at pH 8.0. Calculated values of delta Ed-c, the difference in reduction potential between the heme c and heme d moieties, at pH 8.0 were -25 +/- 5 (unliganded), -10 +/- 5 (enzyme-CO), and -25 +/- 5 mV (enzyme-CN). Relative rates of heme c and heme d reduction were found to be dependent upon type of ligand, reductant, and pH. Evidence for a cooperative heme c-heme d interaction is discussed.     

Optimization of culture conditions and comparison of biomass productivity of three green algae

Culture conditions for the mass production of three green algae, Chlorella sp., Dunaliella salina DCCBC2 and Dunaliella sp., were optimized using a response surface methodology (RSM). A central composite design was applied to investigate the effects of initial pH, nitrogen and phosphate concentrations on the cultivation of microalgae. The optimal growth conditions estimated from the design are as follows: Chlorella sp. (initial pH 7.2, ammonium 17 mM, phosphate 1.2 mM), D. salina DCCBC2 (initial pH 8.0, nitrate 3.3 mM, phosphate 0.0375 mM) and Dunaliella sp. (initial pH 8.0, nitrate 3.7 mM, phosphate 0.17 mM). Culturing the microalgae with the optimized conditions confirmed that the maximum growth rates were attained for these parameters. The optimum CO(2) concentrations of Chlorella sp., D. salina DCCBC2 and Dunaliella sp. were 1.0, 3.0 and 1.0% (v/v), respectively. The specific growth rates (μ) of Chlorella sp., D. salina DCCBC2 and Dunaliella sp. were 0.58, 0.78 and 0.56 day(-1), respectively, and the biomass productivities were 0.28, 0.54 and 0.30 g dry cell wt l(-1) day(-1), respectively. The CO(2) fixation rates of Chlorella sp., D. salina DCCBC2 and Dunaliella sp. were 42.8, 90.9 and 45.5 mg l(-1) day(-1), respectively. Mixotrophic cultivation of Chlorella sp. with glucose increased biomass productivity from 0.28 to 0.51 g dry cell wt l(-1) day(-1). However, D. salina DCCBC2 and Dunaliella sp. were not stimulated by several organic compounds tested.     

隐甲藻深层培养产生二十碳五烯酸的研究

二十碳五烯酸 (Ｃ2 0 :5 ,Ｅｉｃｏｓａｐｅｎｔａｅｎｏｉｃａｃｉｄ ,简称ＥＰＡ)是一种重要的ω 3系列人体必需多不饱和脂肪酸 (Ｐｏｌｙｕｎ ｓａｔｕｒａｔｅｄｆａｔｔｙａｃｉｄｓ,ＰＵＦＡ) [1～ 2 ] 。自从Ｄｙｅｒｂｅｒｇｅ等人报道了二十碳五烯酸对防止和治疗血栓、关节硬化、抗炎症、抗癌、促进脑组织发育等方面具有明显效果以来 ,人们对它的营养和医药价值及生产方法进行了广泛的研究[3～ 6] 。目前 ,二十碳五烯酸主要来源于深海鱼油 ,但其产量不稳定 ,纯化工艺复杂且含有难以消除的鱼腥味 ,难以满足市场的需求。由于二十碳五…     

The activity of lipoxygenase in Arabidopsis thaliana (L.) Heynh -- a preliminary study

The activity of lipoxygenase (EC 1.13.11.12) in Arabidopsis thaliana (L.) Heynh seedlings and mature plants was estimated spectrophotometrically at 234 nm. Linoleic acid was used as a substrate. Lipoxygenase activity showed two pH optima: at 7.0 and 10.0 in seedlings, and at pH 8.0 and 10.0 in leaves of mature plants. Seven-week-old plants were transferred to a hydroponic system and treated with different concentrations of Cd(2+) or Cu(2+) [in microM]: 0, 5, 25, 50, 100 for 7 days. The lipoxygenase activities at pH 8.0 and 10.0 depended on the metal that was added to the nutrient solution. The main change in lipoxygenase activity was under Cd(2+)stress at pH 8.0 and under Cu(2+)excess at pH 10.0.     

Mutant selection of <Emphasis Type="Italic">Hahella chejuensis</Emphasis> KCTC 2396 and statistical optimization of medium components for prodigiosin yield-up

Prodigiosin is a natural red pigment with algicidal activity against Cochlodinium polykrikoides, a major harmful red-tide microalga. To increase the yield of prodigiosin, a mutant of Hahella chejuenesis KCTC 2396, assigned M3349, was developed by an antibiotic mutagenesis using chloramphenicol. When cultured in Sucrose-based Marine Broth medium (SMB), M3349 could produce prodigiosin at 1.628+/-0.06 g/L, while wild type producing at 0.658+/-0.12 g/L under the same conditions. To increase the yield of prodigiosin production by M3349, significant medium components were determined using a two-level Plackett-Burman statistical design technique. Among fourteen components included in SMB medium, NaCl, Na2SiO3, MgCl2, H3BO3, Na2HPO4, Na2SO4, and CaCl2 were determined to be important for prodigiosin production. The medium formulation was finally optimized using a Box-Behnken design as follows: sucrose 10.0, peptone 8.0, yeast extract 2.0, NaCl 10.0, Na2SO4 12.0, CaCl2 1.8, MgCl2 0.7 g/L; and H3BO3 22.0, Na2HPO4 20.0, Na2SiO3 8.0 mg/L. The predicted maximum yield of prodigiosin in the optimized medium was 2.43 g/L by the Box-Behnken design, while the practical production was 2.60+/-0.176 g/L, which was 3.9 times higher than wild type with SMB Medium (0.658 g/L).     

利用乙醇发酵副产CO2培养富含淀粉亚心型四爿藻作为其补充原料

建立了乙醇发酵耦联微藻培养系统,研究了利用酿酒酵母Saccharomyces cerevisiae乙醇发酵副产CO2为碳源,培养富含淀粉的亚心形四爿藻Tetraselmis subcordiformis,作为乙醇发酵补充原料的可行性。在连续光照培养条件下,间歇式培养7 d,反应器中藻细胞密度达到2.0 g/L左右,胞内淀粉含量约45％。微藻细胞收集后,经超声处理和酶法水解,葡萄糖释放量为胞内淀粉总量的71.1％。S. cerevisiae发酵微藻生物质水解液生产乙醇,其得率达到理论值的87.6％。表明乙醇发酵耦联微藻培养可行,既减少了CO2向环境的排放,又收获了富含淀粉的微藻生物质作为乙醇发酵的补充原料,节省粮食类淀粉质原料的消耗。     

木糖发酵产氢菌的筛选及其生长产氢特性研究

利用改进的Hungate厌氧技术, 从牛粪堆肥中分离出一株能有效利用木糖发酵产氢的中温菌HR-1。通过16S rRNA系统发育树分析表明, 菌株 HR-1 与丙酮丁醇梭菌Clostridium acetobutylicum ATCC 824 相似性最高为96%, 结合生理生化和生长特性分析表明, HR-1是梭菌属Clostridium的一个新种, 命名为Clostridium sp. HR-1。菌株HR-1为单胞生长的规则杆状菌(0.3 mm ~0.6 mm)×(1.4 mm~2.3 mm), 革兰氏染色为阴性, 无荚膜、无鞭毛、表面光滑、无明显凸起, 专性厌氧菌。HR-1可在10°C~45°C, pH 4.0~10.0条件下生长; 37°C和pH 8.0分别为其最适生长条件。发酵PYG的主要发酵产物有氢气、二氧化碳、乙酸、丁酸及少量乙醇。HR-1可以利用有机氮源和无机氮源生长并产氢, 酵母提取物是其最佳产氢氮源。HR-1在木糖浓度为3 g/L和初始pH 6.5条件下, 其比产氢量为1.84 mol-H2/mol-木糖, 最大比产氢速率为10.52 mmol H2/h·g-细胞干重。HR-1可以亦利用葡萄糖、半乳糖、纤维二糖、甘露糖和果糖等碳源生长并发酵产氢, 发酵葡萄糖时比产氢量为2.36 mol-H2/mol-葡萄糖。     

Absorption of CO2 in algal mass culture systems: a different characterization approach

For the characterization of CO(2) absorption in aerated microalgal culture systems, a different approach based on K(L)a(O(2)) determination and transformation was studied. To confirm the validity of this method, the influence of reactions between CO(2) and compounds (OH(-), H(2)O, and NH(3)) present in the culture medium upon the absorption mechanism was evaluated under different physical and chemical culture conditions. Under these conditions, knowledge of the relative magnitudes of the diffusion and reaction kinetics permitted the evaluation of their relative importance. For the determination of the parameters required for the calculation of the CO(2) absorption constant, empirical correlations for K(L) (0) and a were used that had been previously verified with experimental data for O(2) absorption. Since, for the conditions studied, the absorption rate was shown to be independent of the chemical reactions taking place in the liquid phase, the K(L)a for CO(2) could be directly related to the K(L)a for O(2) by a simple factor that took into account the difference in aqueous diffusivity of the two gases. Thus, using methods developed for determining O(2) absorption in gas-liquid contactors, it is possible to adequately characterize CO(2) absorption for laboratory and pilot scale algal production systems.     

CO2 biofixation and fatty acid composition of Scenedesmus obliquus and Chlorella pyrenoidosa in response to different CO2 levels

In this study, Scenedesmus obliquus SJTU-3 and Chlorella pyrenoidosa SJTU-2 were cultivated with 0.03%, 5%, 10%, 20%, 30%, 50% CO(2). The two microalgae could grow at 50% CO(2) (>0.69 g L(-1)) and grew well (>1.22 g L(-1)) under CO(2) concentrations ranging from 5% to 20%. Both of the two examined microalgae showed best growth potential at 10% CO(2). The maximum biomass concentration and CO(2) biofixation rate were 1.84 g L(-1) and 0.288 g L(-1) d(-1) for S. obliquus SJTU-3 and 1.55 g L(-1) and 0.260 g L(-1) d(-1) for C. pyrenoidosa SJTU-2, respectively. The main fatty acid compositions of the two examined microalgae were fatty acids with C(16)-C(18) (>94%) under different CO(2) levels. High CO(2) levels (30-50%) were favorable for the accumulation of total lipids and polyunsaturated fatty acids. The present results suggested that the two microalgae be appropriate for mitigating CO(2) in the flue gases and biodiesel production.     

影响木薯次生胚状体发生及植株再生因素的研究

研究了在外植体的不同发育阶段中,碳源以及不同的生长激素配比对木薯次生胚状体诱导及植株再生的影响。结果表明：以固体成熟培养基上生长１５ｄ的胚状体子叶为外植体,次生胚状体的产量最高,达２９．３个成熟胚状体／１个外植体。在次生胚状体的诱导阶段,以麦芽糖（４０ｇ／Ｌ）代替蔗糖作碳源,能同时提高次生胚状体的产量（３２．５个胚次体／１个外植体）及植株再生频率（７４．３％）。２,４－Ｄ与ＰＰ３３３;（０．１ｍｇ／Ｌ）配合能提高植株再生频率到７７．６％。２,４－Ｄ与ＢＡＰ（２ｍｇ／Ｌ）或激动素（２．０ｍｇ／Ｌ）配合则大大降低了胚状体诱导及植株再生频率。     

Optimization of culturing conditions of <Emphasis Type="Italic">Porphyridium cruentum</Emphasis> using uniform design

The red microalga Porphyridium contains many valuable compounds such as polysaccharides, polyunsaturated fatty acids, and phycoerythrin (PE). In this study, a uniform design method and regression analysis were used to investigate the effects of initial pH, light intensity, inoculation ratio, and liquid volume in flask on the optimal biomass, exopolysaccharides (EPS), and PE production of Porphyridium cruentum in a batch culture at laboratory scale. Using regression analysis, we obtained the models to clarify the effects of individual factors and their interactions on the biomass, EPS, and PE production of P. cruentum. The optimal condition for the biomass was the following: pH 5.0, light intensity 7098.0 lx, inoculation ratio 1:17.2, and liquid volume 100.0 ml; for EPS was pH 5.0, light intensity 4501.0 lx, inoculation ratio 1:20, and liquid volume 100.3 ml; while pH 8.0, light intensity 7100.0 lx, inoculation ratio 1:20, and liquid volume 100.3 ml was the best for PE production. The maximum biomass 3.27 g/l, EPS production 543.1 mg/l, and PE production 132.0 mg/l were demonstrated by confirmatory experiment to the optimum culture conditions in a reciprocal shaker. The statistical methods used in the present study are useful strategies for optimizing of culture conditions for other microalgae.     

In situ methane enrichment in anaerobic digestion

A major cost consideration in the use of anaerobic digestion to convert biomass and waste to utility-grade gas is the expense of separating CO(2) from the product gas. Anaerobic digestion has a number of inherent properties that can be exploited to increase the methane content of the gas directly produced by the digester, the most important of which is the high solubility of CO(2)(40-60 times that of methane) in water under digestion conditions. The methane enrichment concept examined in this study involved the recirculation of a liquid stream from the digester through a CO(2) desorption process and the return of the liquid stream back to the digester for absorption of additional CO(2) produced by the conversion of organic materials. A steady-state equilibrium model predicted that a digester gas methane content exceeding 94% could be achieved with this scheme using modest recirculation rates provided a desorption process could be designed to achieve a 60+% CO(2) removal efficiency in the degassing of the liquid recycle stream. Using fixed-film laboratory digesters operated on synthetic feedstocks, the technique of methane enrichment was tested under pressurized and unpressurized conditions. A 93 + 2% methane gas stream was produced from a volatile-acid-fed bench-scale digester simulating the methanogenic stage of two-phase digestion under conditions of (1) a pH swing achieved without caustic addition that allowed digestion at pH 7. 5 and air stripping at pH 6. 5-7. 0, (2) digester pressurization to 30 psig, and (3) a recycle rate of 0. 33 L/L reactor/day. Significant but lower levels of methane enrichment were achieved with the single-stage digester at the low experimental recycle rate. However, the narrow range among all experiments of CO(2) desorption efficiencies achieved in air stripping the recycle stream (35-60% CO(2) removal) suggests that comparable methane enrichment-may be achieved with unpressurized single-stage digestion using greater recycle rates. A materials balance analysis of data from an unpressurized, single-stage digester employing no chemical addition and using laboratory degassing efficiencies indicated that 94% methane could be produced at recycle rates of less than 1. 4 L/L reactor/day with a methane loss of less than 2%.     

Development and bioreactor cultivation of a novel semidifferentiated tissue suspension derived from the marine plant Acrosiphonia coalita

A semidifferentiated tissue culture consisting of linear filaments in liquid suspension was established from Acrosiphonia coalita, a cold-water green macroalga known to express pharmacologically active oxylipins deriving from lipoxygenase metabolism of linolenic acid. The tissue was vegatively propagated by blending the filaments down to 1 to 5 mm in length prior to subculture. The filamentous A. coalita tissue suspension was successfully cultivated in an illuminated, 3-L stirred-tank bioreactor at 12 degrees C, 0.46-vvm aeration rate, 250-rpm mixing speed, and incident illumination intensity of 77 muE m(-2)s(-1). The mean specific growth rate over the exponential phase was 0.185 day(-1) and a final cell density of 1083 mg dry cell weight (DCW) L(-1) was achieved within 15 days of cultivation from an initial cell density of 200 mg DCW L(-1). The addition of 3500 ppm CO(2) to the aeration gas provided a maximum CO(2) transfer rate of six times the maximum CO(2) consumption rate and stabilized the pH to 8.0 during the light phase of growth, but did not improve biomass productivity. (c) 1996 John Wiley & Sons, Inc.     

Scaleup of ajmalicine production by plant cell cultures of Catharanthus roseus

The effect of scaleup on he production of ajmalicine by a Catharanthus roseus cell suspension culture in a selected induction medium were studied. In preliminary experiments it was observed that the culture turned brown and the production was inhibited upon transfer from a shake flask to a stirred bioreactor with forced aeration. Two factors were recognized as the potential origin of the differences between shake flask and bioreactor cultures: gas composition and mechanical shear forces. These factors were studied separately.By recirculating a large part of the exhaust gas, a comparable gas regime was obtained in a bioreactor as occurred in a shake flask cultures. This resulted in the absence of browning and a similar pattern of ajmalicine production as observed in shake flasks. The effect of shear forces could not be demonstrated. However, the experiments showed that the culture may be very sensitive to liquid phase concentrations of gaseous compounds. The effects of k(L)a, aeration rate, CO(2) production rate, and influent gas phase CO(2) concentration on the liquid phase CO(2) concentration are discussed. (c) 1993 John Wiley & Sons, Inc.     

Diffusion-based process for carbon dioxide uptake and isoprene emission in gaseous/aqueous two-phase photobioreactors by photosynthetic microorganisms

Photosynthesis for the generation of fuels and chemicals from cyanobacteria and microalgae offers the promise of a single host organism acting both as photocatalyst and processor, performing sunlight absorption and utilization, as well as CO(2) assimilation and conversion into product. However, there is a need to develop methods for generating, sequestering, and trapping such bio-products in an efficient and cost-effective manner that is suitable for industrial scale-up and exploitation. A sealed gaseous/aqueous two-phase photobioreactor was designed and applied for the photosynthetic generation of volatile isoprene (C(5)H(8)) hydrocarbons, which operates on the principle of spontaneous diffusion of CO(2) from the gaseous headspace into the microalgal or cyanobacterial-containing aqueous phase, followed by photosynthetic CO(2) assimilation and isoprene production by the transgenic microorganisms. Volatile isoprene hydrocarbons were emitted from the aqueous phase and were sequestered into the gaseous headspace. Periodic replacement (flushing) of the isoprene (C(5)H(8)) and oxygen (O(2)) content of the gaseous headspace with CO(2) allowed for the simultaneous harvesting of the photoproducts and replenishment of the CO(2) supply in the gaseous headspace. Reduction in practice of the gaseous/aqueous two-phase photobioreactor is offered in this work with a fed-batch and a semi-continuous culturing system using Synechocystis sp. PCC 6803 heterologously expressing the Pueraria montana (kudzu) isoprene synthase (IspS) gene. Constitutive isoprene production was observed over 192 h of experimentation, coupled with cyanobacterial biomass accumulation. The diffusion-based process in gaseous/aqueous two-phase photobioreactors has the potential to be applied to other high-value photosynthetically derived volatile molecules, emanating from a variety of photosynthetic microorganisms.     

Bicarbonate produced from carbon capture for algae culture

Using captured CO(2) to grow microalgae is limited by the high cost of CO(2) capture and transportation, as well as significant CO(2) loss during algae culture. Moreover, algae grow poorly at night, but CO(2) cannot be temporarily stored until sunrise. To address these challenges, we discuss a process where CO(2) is captured as bicarbonate and used as feedstock for algae culture, and the carbonate regenerated by the culture process is used as an absorbent to capture more CO(2). This process would significantly reduce carbon capture costs because it does not require additional energy for carbonate regeneration. Furthermore, not only would transport of the aqueous bicarbonate solution cost less than for that of compressed CO(2), but using bicarbonate would also provide a superior alternative for CO(2) delivery to an algae culture system.