多变鱼腥藻在不同氮源培养条件下光能转换效率的研究

依公式PE=KY,其中K等于生物量的热值(每克干重千卡),Y等于产率即每吸收千卡光能所产生的生物量的干重,测试了在无氮和有结合氮培养下的多变鱼腥藻(Anabaena variabilis)的光能转化效率。结果指出在无氮培养下的最高PE_(N2)为8.1%,在结合氮(NH_4Cl)培养下PE_(NH_4~ )为5.8%。对这种差异性作了简要讨论。     

氮限制对普通小球藻积累油脂过程中生化组成与光合生理的影响

以产油普通小球藻(Chlorella vulgaris Beijierineck)为材料,通过设置不同的初始硝酸钠浓度,研究不同程度的氮素限制对普通小球藻生长、生化组成及光合生理的影响。结果显示,在实验设置的4个氮素浓度下(18.0、9.0、4.5、3.6 mmol/L),普通小球藻生物量无显著差异,但较低的初始氮浓度明显促进了其油脂积累,其中4.5 mmol/L组藻细胞的总脂含量和总脂产率最高,分别达到干重的48.32%及0.0931 g·L-1·d-1,显著高于18.0 mmol/L的正常氮组(P0.05)。4个氮浓度组藻细胞内碳水化合物及可溶性蛋白的含量均有下降,油脂积累量逐渐升高,2个低氮组(4.5 mmol/L和3.6 mmol/L)在培养初期藻细胞内可溶性蛋白大量降解,油脂及碳水化合物有所积累,但碳水化合物随后逐渐转化为油脂。PSⅡ最大光能转化效率(Fv/Fm)、实际光能转化效率(Yield)以及相对电子传递效率(ETR)在培养过程中均呈下降趋势,77 K低温荧光结果显示,培养初期,2个光系统之间存在光能调配和状态转化。代表固碳能力的Rubisco活性表现为在较高氮浓度组先上升后下降,而在2个低氮组呈下降趋势;4个氮浓度组Rubisco的活化程度均呈先下降后上升的趋势。该研究表明适宜氮素限制促进普通小球藻油脂积累的过程中碳素分配和光合生理存在协同调控。     

限氮培养对小球藻水分含量和叶绿素荧光参数的影响

限氮培养是提高小球藻油脂含量的一种方法,本研究探讨了小球藻限氮培养过程中藻细胞的生物量、水分含量和叶绿素荧光参数的变化。结果表明:在限氮培养条件下,小球藻藻细胞的生物量和水分含量分别下降了18%和7%;藻细胞的最大光能转化效率(Fv/Fm),表观量子效率(α)和最大光合电子传递速率(rETRmax)在整个限氮培养过程中均快速下降,到培养末期下降至接近于0,显著低于对照;半饱和光强(Ek)在对数期迅速下降,到稳定期后显著上升;最小荧光(F0)在整个限氮培养过程中显著上升。可见,限氮培养显著影响了小球藻细胞光系统Ⅱ的结构和功能。     

真养产碱菌由丁酸积累聚β-羟基丁酸的研究

真养产碱菌(Alcaligenes eutrophus)H16(ATCC 17699)能以丁酸为唯一碳源在无氮合成培养基中积累大量生物可降解的聚β-羟基丁酸(PHS)。将此菌在丰富培养基中预培养36小时后转入无氮合成培养基甲,在30℃、pH8．0条件下培养48小时,积累的PHB可达细胞干重的63％(w／w)。较高浓度的丁酸对PHB的积累有抑制作用。采用丁酸自动流加法控制pH值的工艺可降低丁酸的抑制作用。此时PHB的产率达0．4g/g丁酸,PHB比产生率60)达0．1g·g生物量-1·h—-1。     

氮、磷对缺刻缘绿藻生长、总脂及花生四烯酸积累的影响

本文以缺刻缘绿藻(Parietochloris incisa)为实验材料,研究了其在四种不同氮、磷浓度下的生长、总脂(TL)及花生四烯酸(AA)含量的变化,分析测定了低氮和低磷浓度下脂肪酸的组成。结果表明:在BG-11培养基基础上,氮浓度的改变对缺刻缘绿藻的生物量影响不明显,不同氮浓度下的最终生物量均在2.1 g.L-1左右。在低氮浓度下TL和AA达到最大,分别为33.37%(%干重)和36.63%(%总脂肪酸,TFA),其中AA占藻体干重的11.56%。不同磷浓度对缺刻缘绿藻的生长有显著影响,最终生物量在0.90～2.07 g.L-1之间。TL在8～20 mg.L-1的磷浓度范围内没有明显变化,为28%左右。TL与氮、磷浓度呈显著负相关关系,且低氮有利于AA的积累。     

施氮和减水对中亚热带壳斗科三种幼树生物量及其分配的影响

土壤氮素和土壤含水量是森林生态系统中限制植物生长的重要因子。为探讨常绿阔叶树种对模拟氮沉降增加和降水减少的响应,以同质园中自然生长的壳斗科(Fagaceae)丝栗栲(Castanopsis fargesii)、大叶青冈(Cyclobalanopsis jensenniana)和麻栎(Quercus acutissima)五年生幼树为对象,比较了对照(CK)、施氮(+N,施氮60 kg hm~(-2) a~(-1))、减水(-W,减少自然降水的50%)以及施氮和减水(+N-W,施氮60 kg hm~(-2) a~(-1)和减少自然降水的50%)对总生物量、各器官生物量及其生物量分配的影响。研究表明:(1)施氮显著增加了三种幼树的总生物量及各器官生物量(P0.05)。(2)减水未引起三种幼树的总生物量及各器官生物量的显著下降(P0.05)。(3)除麻栎树叶生物量、树枝生物量外,施氮和减水交互作用对三种幼树总生物量及各器官生物量没有明显影响(P0.05)。(4)施氮显著提高了丝栗栲幼树的干重比、大叶青冈幼树的干重比和枝重比(P0.05),降低了大叶青冈的叶重比和根重比(P0.05)。(5)减水导致丝栗栲幼树和麻栎幼树的根重比、麻栎幼树的根冠比显著增加(P0.05),引起丝栗栲幼树的枝重比、麻栎幼树的叶重比、枝重比和干重比显著降低(P0.05)。(6)施氮和减水交互作用显著提高了丝栗栲幼树的根重比(P0.05),降低了麻栎幼树的干重比(P0.05)。     

氮胁迫对埃氏小球藻生长及油脂积累的影响

以生长快、可除污的埃氏小球藻株系SXND-25为试材,研究不同氮浓度培养条件对其生物量和油脂产量的影响,以期建立优化培养体系利用该株小球藻生产优质生物燃油。以硝酸钠为氮源、BG11培养基中的氮浓度为基准(1.5 g/L),设置氮浓度梯度对小球藻进行培养。通过光密度测定、尼罗红染色、转酯化法抽提油脂和GC分析,对小球藻生物量、油脂含量及脂肪酸组分进行分析。结果显示,培养8 d时,在氮浓度为1.5 g/L时,生物量达到最大,干重为3.4 g/L,而油脂含量仅为28.24%,油脂产量为0.96 g/L;在氮浓度为0 g/L时生物量最小,干重为0.49 g/L,而油脂含量最高,为44.57%,油脂产量为0.22 g/L;在氮浓度为0.75 g/L时,干重为3.2 g/L,油脂含量为40.36%,油脂产量最高为1.3 g/L,是标准氮浓度下油脂产量的1.4倍。0.75 g/L氮浓度下连续培养8 d,藻油脂肪酸组成更适于制取优质生物柴油。综合生物量、油脂含量及脂肪酸组成等指标,确定0.75 g/L氮浓度为该埃氏小球藻株系规模化培养以生产优质生物燃油的优化参数。     

不同氮素水平对产油尖状栅藻生长及光合生理的影响

在300μmol photons·m^-2·ｓ^-1光照下,以不同初始氮素营养条件的改良BG-11培养基为基础培养基,在Ø6 cm的玻璃柱状光生物反应器通气(加富1.5% CO₂)培养绿藻尖状栅藻(Scenedesmus acuminatus),分析探讨藻细胞的生长及光合生理与氮素营养的关系。结果表明,不同氮素实验组藻细胞的最大生物量有差异,氮浓度为6mmol/L实验组的生物量最高,为5.19g/L。与初始氮浓度18 mmol/L相比,较低的氮浓度9 mmol/L、和 6 mmol/L 在培养前期对尖状栅藻的生长具有明显的促进作用。藻细胞叶绿素a、b及总类胡萝卜素含量与培养液的氮素营养水平呈正相关。低氮条件有利于总脂积累,总脂含量和单位体积总脂产率显著高于全氮组(P<0.05),3.6 mmol/L实验组的总脂含量最高,为干重的54%,比全氮组高17%(P<0.05)。培养后期随着藻细胞总脂的积累,总碳水化合物和总蛋白含量明显下降(P<0.05)。PSⅡ最大光能转化效率(Fv/Fm)、实际光能转化效率(Yield)以及相对电子传递效率(ETR)均随氮素限制而显著下降(P<0.05),光合速率在不同生长阶段呈先上升后下降的趋势,呼吸速率在培养周期内缓慢上升,说明藻的生长、油脂的积累与细胞光合生理状况以及氮素营养水平直接相关。     

银鹊树群落生物量和能量的分配

 本文研究了安徽大别山天然林内16年生银鹊树和引种于南京的银鹊树幼苗及人工幼林的生物量,分析了光能利用率。研究结果表明：(1)常规芦蒹遮光,一龄苗的生物量为1777.5kg／ha。以一层塑料纱遮光处理的幼苗生物量最大,全光照的幼苗生物量居第二、三层纱遮光生物量最小。(2)天然林内16年生单株银鹊树地上部分干重为107.77kg。(3)8年生人工银鹊树林总生物量为80.63t／ha,其中乔木层平均净生产量为9.563t／ha·a,高于湖南会同、朱亭及江苏南部的杉木林。(4)银鹊树林总初级生产量为1219.18g／m2·a;其中乔木层为956.25g／m2·a,草本及天然幼苗为161.10g／m 2·a,枯枝落叶为101.83g／m2·a．光能利用率为0.527%,其中乔木层的光能利用率为0.417%。     

施用泥炭对风沙土改良及蔬菜生长的影响

通过盆栽试验比较了施用不同剂量的泥炭(0％、2％、5％、8％及10％)对风沙土改良的效果和对白菜生长及产量的影响。结果表明,泥炭能增强风沙土的持水能力,降低土壤的pH值,增加土壤中有机质、全氮、速效氮和速效磷等的含量;白菜根系长度、生物量、高生长和地上部分的生物量均有增加,其中8％泥炭处理为最佳,其根系长度、根鲜重、干重、高生长、地上部分鲜重、干重依次比对照增加71％、402％、464％、107％、847％和1001％;同时施用泥炭还有利于提高白菜干物质的积累及其品质。     

Physiology of,an enzyme production by,plant cell cultures

Red kidney bean (Phascolus vulgaris) cells, derived from roof, callus, were grown in suspension culture in shake flasks and in laboratory fermentors using batch and continuous batch culture techniques. The medium contained casein hydrolysate, sucrose, inorganic salts, vitamins, and growth hormones. In continuous batch culture yields of up to 171 g wet weight, (8.5 g dry weight) per liter were obtained in 7 days. Organic nitrogen was used preferentially. Growth on nitrate was considerably slower than on organic nitrogen sources. Indole acetic and naphthalene acetic acids were not essential for good growth of the cells whereas kinetin and 2, 4-D were. The optimum pH for growth was about p11 4.5. The presence of amylase and peroxidase was detected in culture filtrates. Amylase activity was low in either the presence or the absence of starch in the medium. Peroxidase production could be related directly with growth of the culture. Maximum peroxidase yield, as measured by the guaiacol method and expressed as horse radish peroxidase, was 1.25 × 10^?8 M.     

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.     

Production of Bacterial Cells from Methane

A mixed methane-oxidizing bacterial culture capable of stable and predictable growth in continuous culture was isolated. The culture consisted of two types of gram-negative nonsporulating rods resembling pseudomonads. The culture grew well at 45 C on an inorganic medium without asepsis. Specific metal requirements for Ca²⁺, Cu²⁺, MoO₄²⁻, Zn²⁺, Mn²⁺, Mg²⁺, and Fe³⁺ (or Fe²⁺) were shown. The cells grown in continuous culture contained 11.7 to 12.1% total nitrogen. From an animal nutrition standpoint, the distribution of amino acids was satisfactory. The continuous fermentation was operated over a range of steady-state dilution rates from 0.085 to 0.301 hr⁻¹. The maximum specific growth rate for the culture, μ_max, was 0.303 hr⁻¹ (doubling time 2.29 hr). The average yield for all fermentations analyzed was 0.616 g (dry weight of cells per g of methane used and 0.215 g (dry weight) of cells per g of oxygen used. The yields on both methane and oxygen were higher for the oxygen-limited than for the methane-limited fermentations. The maximum productivity attained in the fermentor was 2.39 g (dry weight) of cells per hr per liter at a dilution rate of 0.187 hr⁻¹ and a cell concentration of 12.8 g (dry weight) of cells per liter. The limit on maximum cell productivity was determined only by the mass transfer rate of oxygen in the fermentor. The simultaneous volumetric mass-transfer coefficients (k_La in hr⁻¹) for oxygen and methane were determined. The results appear to indicate an oxygen to methane mass-transfer coefficient ratio of approximately 1.4.     

A novel approach for medium formulation for growth of a microalga using motile intensity

Motile intensity of the cells, defined as the specific mean kinetic energy, was measured by image analysis and used to formulate a suitable medium for the cultivation of a motile microalga. Nitrogen source at 60 mg/L was used as the target component. The cells grown in a medium containing urea showed the highest motile intensities during cultivation when compared to the cells grown with NH(4)Cl or (NH(4))(2)SO(4) as the nitrogen source. The urea culture gave the highest biomass yield and lipid content of 1.06+/-0.12 g/L and 22.34+/-2.56%, respectively after 150 h of cultivation. These results indicated a strong dependence of motile intensity on the nitrogen source used in the growth medium. This concept, which requires only a small droplet of the sample, can find potential application in the design and optimization of culture media.     

Influence of dilution rate on the morphology and technological properties ofLactobacillus delbrueckii subsp.bulgaricus

Lactobacillus delbrueckii subsp.bulgaricus ATCC 11842 was grown in a chemostat at 45°C and pH 5.5 using glucose as the carbon source, with the aim of optimizing biomass production. Cells were grown in a complex medium under nitrogen. At dilution rates lower than 0.18h^–1, it was difficult to keep steady-state conditions and pleomorphic forms were observed. The addition of 30mM Ca²⁺ and Mn²⁺ reverted the cells to normal shape: 30mM Mg²⁺ had no effect. Increasing the dilution rate resulted in normal morphology without the addition of any cations. Under these conditions, a maximum productivity of 1.24g dry biomass 1^–1 h^–1 was obtained. The maximum growth yield, corrected for maintenance, was 30g biomass mol^–1 glucose and the maintenance energy was 0.26g glucose g^–1 biomass h^–1. Lactate was the main fermentation product at all glucose concentrations used in the fed medium. Cells grown at high dilution rates had normal technological properties (acid production and proteolysis) when tested in milk.     

Issues in the culture of the extremely thermophilic methanogen, Methanothermus fervidus

Basic issues in the culture of the extremely thermophilic archaeon, Methanothermus fervidus, have been investigated, including culture medium formulation, substrate yield and product yield coefficient, growth rate and stoichiometry, and H(2) uptake kinetics. The pH optimum for growth of this organism was estimated at 6.9. Growth medium buffered with PIPES instead of bicarbonate supported both increased growth rate and maximum biomass concentration. Substitution of titanium(III) citrate for the reducing agent sodium sulfide improved culture performance as well. However, independent adjustment of iron and nickel concentrations from 11 to 111 muM, respectively, and carbon dioxide partial pressure from 5 to 20 psia did not impact the culture of M. fervidus significantly. An elemental balance approach was utilized to aid in design of a defined medium to support growth to a target maximum biomass concentration of at least 1.0 g dry wt/L. The growth of this organism was limited by H(2) availability in this reformulated culture medium. The maximum growth rate and biomass concentration achieved in anaerobic vials with the defined medium was 0.16 h(-1) and 0.74 g dry wt/L, respectively. This maximum biomass concentration was a 72% improvement over that obtained with a literature-based defined medium. The Monod parameter, K(s), with H(2) as limiting substrate, was estimated at 1.1 +/- 0.4 psia (55 +/- 20 muM in the broth), based on a H(2) consumption study. Representative values for the substrate yield, Y(X/CO(2) ), and product yield coefficient, Y(CH(4)/) (X), were determined experimentally to be 1.78 +/- 0.04 g dry wt/mol CO(2), and 0.52 +/- 0.01 mol CH(4)/g dry wt, respectively. A bench-scale fermentation system suitable for the culture of extremely thermophilic anaerobes was designed and constructed and proved effective for the culture of M. fervidus. (c) 1993 Wiley & Sons, Inc.     

利用市政污水培养Chlorella vulgaris生产生物柴油

为了考察利用南昌市政污水规模化培养富油微藻生产生物柴油,同时达到净化污水的目的,取南昌市青山湖污水处理厂未经任何处理的市政污水作为普通小球藻(Chlorella vulgaris)生长的培养液。监测了C.vulgaris在市政污水中连续培养10 d的特定生长率、生物质产量以及与之相关的市政污水中氨氮(NH4+-N)、总磷(TP)、化学需氧量(COD)、总悬浮固体(TSS)和挥发性悬浮固体(VSS)的清除情况。实验表明:营养物质的水平显著地影响了C.vulgaris的生长。C.vulgaris的生长率在培养8 d后达到最大,OD680为2.856,总的生物质产量日均最大积累速率为0.01 g/L,油脂含量为干质量的18%,油脂的平均日产量为0.001 g/L。培养10 d内NH4+-N、TP和COD的去除率分别为50.0%、32.1%和26.0%,TSS和VSS的日平均去除速率分别为0.01 g/L和0.006 1 g/L。     

Culture conditions and the development of the photosynthetic mechanism; influence of light intensity on photosynthetic characteristics of Chlorella

1. Chlorella pyrenoidosa has been grown in a continuous-culture apparatus under various light intensities provided by incandescent lamps, other conditions of culture being maintained constant. Light intensity curves for cells immersed in the No. 11 Warburg buffer and in Knop''s solution + 4.4 per cent CO₂ at a saturating light intensity were determined as characteristics of the photosynthetic mechanism. These characteristics were referred to the centrifuged cell volume as an index of quantity of cellular material. 2. Cells grown at intensities in the range of about 35 f.-c. develop a capacity for a high rate of photosynthesis (c.mm. O₂/hour/c.mm. cells). At culture intensities above or below this range the cells produced have a lower capacity for photosynthesis. A similar effect is observed for rate of photosynthesis per unit dry weight or rate per unit cell nitrogen. 3. The rate of photosynthesis per cell or rate per unit chlorophyll shows no maximum at any light intensity of culture but increases continuously throughout the range of light intensities studied. 4. Maximum rate of growth is attained at a light intensity of about 100 f.-c. The hypothesis is advanced that at culture intensities above that needed to give maximum rate of growth (100 f.-c.) a mechanism is developed which opposes the photosynthetic process and removes the photosynthetic products. 5. The low capacity for photosynthesis shown by cells grown at culture intensities below 35 f.-c. finds no immediate explanation. 6. The shape of the light intensity curve is markedly affected by the light intensity at which the cells have been cultured. Cells grown at lower intensities give light intensity curves approaching the Blackman type with a short transitional region between light limitation and light saturation.     

Intrinsic autotrophic biomass yield and productivity in algae: experimental methods for strain selection

Using an analogy with fed-batch heterotrophic growth, the algal photoautotrophic yield Φ(DW) (in grams of dry weight biomass synthesized per micromole of absorbed photons) was derived from the algae batch growth behavior in nutrient-replete medium. At known levels of incident light, the yield Φ(DW) enables the estimate of a maximum productivity, and is therefore critical to compare and select algal cultures and growth conditions for large-scale production. The algal culture maximum growth rate was shown to be an unreliable indicator of autotrophic biomass yield. The developed carbonate addition method (carbonate addition, neutralization, and sealing) alleviated carbon limitations otherwise seen in aerated batch cultures, leading to two to five fold higher yield estimates. The fully defined FLX growth medium with variable ionic strengths (FLX1-100) supported excellent growth in most cultures tested. The chosen experimental methods and versatile FLX medium proved well-suited for small sample volumes and a high number of samples.