Effects of nutrient supply methods and illumination with blue light emitting diodes (LEDs) on astaxanthin production by Haematococcus pluvialis

In order to increase the cell concentration and the accumulation of astaxanthin, the effects of nutrient concentration, pH, illumination and methods of supplying nutrients were studied for the cultivation of Haematococcus pluvialis. The replacement of media to avoid the deficiency of nutrients increased the cell concentration above 1 mg-dry cell cm(-3) without induction of astaxanthin accumulation. Illumination with blue light emitting diode lamps and nutrient starvation induced accumulation of astaxanthin, and the interactive effects of these two increased the astaxanthin concentration to 76 mug cm(-3).     

Effect of flashing light from blue light emitting diodes on cell growth and astaxanthin production of Haematococcus pluvialis

To conserve energy in the production of astaxanthin by the green alga Haematococcus pluvialis, we utilized intermittent flashing light from blue light emitting diodes (LEDs) and investigated the effects of the incident light intensity (2-12 micromol m(-2) s(-1)), duty cycle (17-67%) and frequency (25-200 Hz) of flashing on the cell growth and astaxanthin production. In the above ranges, the final astaxanthin concentration under illumination by flashing light was significantly higher than that obtained under illumination with continuous light at the same incident intensity. For example, flashing light at an incident intensity of 8 micromol m(-2) s(-1) gave the same final astaxanthin concentration that was obtained under continuous light illumination at 12 micromol m(-2) s(-1), thus reducing energy consumption by 1/3. We therefore conclude that flashing light from blue LEDs is a promising illumination method for indoor algal cultivation using photobioreactors.     

Effect of light intensity and frequency of flashing light from blue light emitting diodes on astaxanthin production by Haematococcus pluvialis

Flashing light from blue light emitting diodes is an effective method for the reduction of energy consumption in the bioproduction of astaxanthin by Haematococcus pluvialis. We investigated the effects of light intensity and frequency on the final astaxanthin concentration in bioproduction by H. pluvialis grown mixotrophically. The final astaxanthin concentration under illumination with flashing light, with frequencies ranging from 25 to 200 Hz, was dependent on the light intensity and on the duty cycle and was equivalent, or higher, in comparison with that under illumination with continuous light at the same incident intensity. The light intensity determined the maximum attainable concentration of astaxanthin under continuous illumination. Under illumination with flashing light, the ratio of the final astaxanthin concentration to the maximum concentration at a specific light intensity was correlated to the duty cycle in the frequency range from 25 to 200 Hz. The effect of lower frequencies on enhanced astaxanthin production under flashing light was also studied; at levels as low as 1 Hz, higher final astaxanthin concentrations were observed under flashing light compared to concentrations attained under continuous light.     

金属离子对法夫酵母产虾青素影响的研究

为了研究金属离子对法夫酵母产虾青素的影响并优化出有利于法夫酵母产虾青素的金属离子,用单因子实验方法研究不同离子对法夫酵母产虾青素的影响并用正交实验方法对金属离子进行了配比优化。在培养基中添加Zn2+和Mn2+能增加细胞干重,在培养基中添加Zn2+、Fe3+、Mn2+和Cu2+能使培养液中虾青素的浓度增加,在培养基中添加Fe3+和Cu2+能使细胞中虾青素的含量增加。在培养基中添加3μmol/L的Mn2+、1μmol/L的Zn2+、1μmol/L的Fe3+、5μmol/L的Cu2+有利于法夫酵母虾青素的合成,用这些金属离子批式培养法夫酵母,总细胞得率为0.349 g/g(葡萄糖),总虾青素得率为0.266 mg/g(葡萄糖),细胞内虾青素最高含量为0.81 mg/g。     

营养强化混养条件下提高色绿藻生物量和虾青素产量

本研究在混养条件下,系统地比较了葡萄糖浓度、氮源种类以及不同碳氮比对色绿藻生物量和虾青素产率的作用规律。目的是在短时间内达到最高生物量同时获得较高含量的虾青素,为建立色绿藻高密度快速扩种和诱导积累虾青素应用技术提供科学依据。研究结果表明:在混养条件下,当葡萄糖浓度一定时,硝酸钠是细胞生长所需的最优氮源,6 d可达到最高生物量浓度9.23 g/L,平均比生长速率为0.24/d,虾青素产量为12.38 mg/L,虾青素占总类胡萝卜素的比例高达46.94%。至于不同碳氮比、葡萄糖浓度对色绿藻生物量和虾青素生产的影响,当葡萄糖浓度为30 g/L、C/N比为34为细胞生长的最优条件,生物量浓度最高为11.28 g/L,平均比生长速率高达0.32/d;虾青素含量显著优于其他组(p0.05),虾青素的产量为21.77 mg/L,虾青素占总类胡萝卜素的比例进一步提高到52.71%。本研究结果对于色绿藻高密度快速生长并积累大量虾青素的放大技术开发具有重要的指导意义。     

不同诱导条件强化佐夫色绿藻积累虾青素

佐夫色绿藻具有多种营养生长方式且可以在诱导条件下合成虾青素,是一种藻源天然虾青素生产的新型替代微藻。本研究系统探讨了以醋酸钠为碳源时,醋酸钠浓度、补料方式、p H以及乙醇对色绿藻积累虾青素的影响,并在室外300L管道光生物反应器中对上述优化的诱导条件进行放大验证。结果表明:采用2.5 g/L醋酸钠、每6 d补加2.5 g/L醋酸钠、培养基p H控制在6.5～8.3和添加2%乙醇时,虾青素的含量最高为3.71 mg/g,较优化前的虾青素的含量提高了31.71%,产量为5.37 mg/L。在室外300 L管道光生物反应器中,其最高虾青素含量和产量分别为3.44 mg/g和1.10 mg/L。本研究采用不同诱导条件强化佐夫色绿藻胞内虾青素的积累,验证了佐夫色绿藻在户外光生物反应器规模诱导培养以生产虾青素的可行性。     

光质对苜蓿芽苗菜营养品质和抗氧化特性的影响

采用发光二极管精确调制光质和光量,研究光谱能量分布对苜蓿芽苗菜营养品质和抗氧化特性的影响,以黑暗作为对照。结果表明：与对照和其他光质处理相比,蓝光能显著提高苜蓿芽苗菜中可溶性蛋白、游离氨基酸、VC、总酚类物质和总黄酮的含量以及清除1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基的能力,并显著降低硝酸盐的含量;红光能显著提高鲜质量产量;白光处理更利于提高干质量产量,显著提高类胡萝卜素和硝酸盐的含量;黄光下培养6、8、12 d的苜蓿芽苗菜槲皮素含量显著提高,苯丙氨酸解胺酶（phenylalanine ammonia-lyase,PAL）活性也相应提高,且槲皮素含量与PAL活性呈显著正相关。总体而言,蓝光有利于提高苜蓿芽苗菜的营养品质。     

Effect of illumination intensities on astaxanthin synthesis by Xanthophyllomyces dendrorhous and its mutants

The aim of the study was to select optimal illumination for Xanthophyllomyces dendrorhous DSM 5626 and its mutants: 26UV, 10BE, 13B, and 34B for astaxanthin production. The strains were cultivated on YM medium at an illumination of 0–5,000 lx. The highest yields of astaxanthin were found in cultures at 600 lx. The maximum pigment production for the parental strain was 0.95 mg/L and 0.19 g/kg dry cell weight (DCW), while for mutants 1.23–1.51 mg/L and 0.34–0.39 g/kg DCW. It was calculated that the application of adequate values of illumination (within the range of 670–718 lx), determined on the basis of regression models, may improve astaxanthin production by approximately 5–15%, depending on the strain. This was confirmed in the verification experiments for the parental strain and mutants: 10BE, 13B, 26UV, but for 34B at 718 lx the volumetric astaxanthin production was found to be higher than predicted by the model.     

培养基pH调控法高密度发酵唾液乳杆菌XH4B研究

本研究以MRS培养基为基础,通过优化碳、氮源及无机盐的配方和用量,再结合补料发酵,最终实现唾液乳杆菌XH4B高密度培养的目的。以乳酸菌的生物量为指标,同时考查发酵液pH值、乳酸含量等,最终确定酵母粉和蔗糖为最佳氮、碳源,同时增加乙酸钠用量至2%、磷酸二氢钠0.6%,可以对发酵液酸化时提供一定的缓冲作用。采用优化的PY-Suc培养基,唾液乳杆菌XH4B的生物量最高能达到6.91 g/L,明显高于MRS培养基的5.01~6.30 g/L(P0.05)。等量补料培养并且采用NaOH中和发酵液pH值时,乳酸最高积累速度可以达到5.958 g/(L·h),但是随着培养时间延长,积累速度迅速下降。发酵酸化较严重时(乳酸含量9~10 g/L),唾液乳杆菌XH4B的生物量积累变缓。结论:优化MRS培养基,并加大乙酸钠、磷酸二氢钠等能够缓冲发酵液的无机盐用量,结合补料发酵,可以实现唾液乳杆菌XH4B的高密度培养。     

全营养流加对谷氨酸棒杆菌发酵产L-异亮氨酸的影响

在谷氨酸棒杆菌发酵产L-异亮氨酸的过程中,发酵后期菌体活力变弱,副产物增多,是限制L-异亮氨酸产业化的主要因素。研究通过3个阶段全营养流加策略探究最适发酵条件。首先,为解决L-异亮氨酸发酵中后期菌种活力下降的问题,实验通过利用发酵中后期全营养培养基流加策略,使得L-异亮氨酸达到了33.0 g/L。其次,为了解决初始发酵培养基高营养抑制问题,采用低浓度初始发酵培养基偶联发酵过程流加全营养控制策略,L-异亮氨酸达到了36.8 g/L。最后,由于玉米浆的高用量造成发酵染菌、起泡过多及后提取困难等产生的问题,通过清洁氮源丝肽粉等比例替换玉米浆全营养流加实验,使得副产物缬氨酸(valine,Val),亮氨酸(leucine,Leu),丙氨酸(alanine,Ala)分别降低到1.4、0.8、0.5 g/L,比初始降低了82.5%、86.7%和88.9%。通过上述3个阶段全营养流加策略,使得L-异亮氨酸产量提升的同时,副产物生成也得到有效的抑制。     

Inhibitory effect of mineral ion accumulation on high density growth of the hyperthermophilic archaeon Sulfolobus solfataricus

A fed-batch operation for high density cultivation of Sulfolobus solfataricus (DSM 1617) in a bench-top fermentor using a feed medium composed of glucose and yeast extract was investigated. The highest maximal cell density obtained in controlled fed-batch cultures was 21.7 g/l. Although higher yeast extract concentrations in the medium favored greater cell biomass yield, cell growth ceased with low cell densities. It was observed that large amounts of inorganic ions, such as sulfate, ammonium, potassium and phosphate ions, were accumulated in the culture broth at higher yeast extract concentrations. This was due to either the addition of the titrant or feeding of yeast extract during cultivation. Fed-batch cultures with additional mineral salts in the feed medium showed much lower cell biomass, indicating that accumulation of inorganic ions has a significant inhibitory effect on the growth of S. solfataricus. Inhibition of cell growth by the presence of mineral ions was further confirmed by the batch culture experiments. Some plausible mechanisms which can account for the growth inhibition at higher mineral ion concentrations have been suggested.     

碳酸氢铵为氮源对螺旋藻培养的影响

以碳酸氢铵作为氮源,研究在分批培养及流加培养条件下其对螺旋藻生长的影响。结果表明：当培养液中碳酸氢铵浓度小于5mmol/L时,螺旋藻生长正常;碳酸氢铵浓度超过5mmol/L时,螺旋藻生长受到抑制,解体死亡。采用生物量反馈补料的流加策略可以使培养液中螺旋藻生物量达到3.08g/L,产率达到0.26g/(L ·d),藻体中蛋白质及叶绿素含量分别达到65.06%和13.37mg/g,结果证实了碳酸氢铵为氮源高密度培养螺旋藻的可行性。     

Optimization of L-lactic acid feeding for the production of poly-D-3-hydroxybutyric acid by Alcaligenes eutrophus in fed-batch culture

We investigated optimization of the feeding of L-lactic acid for the production of poly-D-3-hydroxybutyric acid [P(3HB)] by Alcaligenes eutrophus in a fed-batch culture system. An acidic substrate solution was fed automatically so as to maintain the pH of the culture liquid at 7.0. Feeding of a substrate solution containing 45% (w/v) L-lactic acid, 6.2% (w/v) sodium L-lactate, 5.8% (w/v) ammonia water and 1.8% (w/v) potassium phosphate [at a molar ratio of carbon to nitrogen (C/N molar ratio) of 10], allowed the L-lactate concentration in the culture liquid to be maintained at approximately 2 g/l and the cell concentration reached 27.4 g/l after 15 h of cultivation. To promote P(3HB) production, a two-stage fed-batch culture consisting of a culture for cell growth and one for P(3HB) accumulation was carried out. When the substrate solution, whose C N molar ratio was 23, was fed during the P(3HB) accumulation phase, the cell concentration and the P(3HB) content in the cells reached 103 g/l and 57.6% (w/w), respectively, in 51.5 h.     

红发夫酵母生长和虾青素积累培养参数的优化

在摇瓶中应用二次正交旋转组合设计研究了不同培养时间、接种量、种子液培养时间和装液量对红发夫酵母Phaffia rhodozyma As2.1557生长和细胞虾青素含量的影响,并对培养参数进行了优化.结果表明:接种量、培养时间和装液量对Phaffia rhodozyma As2.1557生长和虾青素积累有显著影响,最佳生长参数为:装液量每瓶30 mL(250 mL摇瓶),摇瓶培养时间96 h,接种量12%,种子培养时间60 h.     

佐夫色绿藻高产虾青素的诱导条件及发酵工艺优化

本研究了不同诱导条件及光发酵罐培养工艺对混养佐夫色绿藻的影响,通过参数优化提高了藻细胞生物量和虾青素积累量.本研究首先系统地比较了在摇瓶系统中不同混合碳源和过氧化氢浓度对佐夫色绿藻的生长和虾青素积累的影响,并在光发酵罐中研究了恒定高光强、低光强-高光强以及低光强-高光强-补加过氧化氢三种不同发酵工艺对佐夫色绿藻积累虾青...     

天然虾青素生产方法研究进展

为进一步提高湖泊红球藻（Haematococcus lacustris）的工业利用价值,本研究使用常压室温等离子体（atmospheric and room temperature plasma,ARTP）诱变仪对湖泊红球藻进行等离子诱变。以藻细胞致死率为指标确定等离子诱变的适宜输入功率和诱变时间。诱变之后通过固体平板培养初筛和液体培养复筛获得高产虾青素的突变藻株。再以藻细胞密度为指标采用单因素实验及正交试验对高产藻株的营养生长阶段的培养条件进行优化,并筛选虾青素诱导阶段适宜虾青素积累的高光照条件。在优化的培养条件下多次继代后观察高产突变藻株的遗传稳定性。结果表明,湖泊红球藻等离子诱变的适宜条件是功率240 W、诱变时间150 s或功率400 W、诱变时间120 s。通过初筛和复筛获得生长快、虾青素产量高的突变藻株有11株,其中编号为HP3的突变藻株生长最快、虾青素产量最高,培养后藻细胞密度和虾青素产量较出发株分别提高了25.5%和61.6%。经过两阶段培养条件的优化,HP3的藻细胞密度和虾青素产量较优化前分别提高了14.3%和19.3%,达7.2×10⁵ cell/mL和31.264 mg/L。湖泊红球藻高产突变藻株HP3多次继代后藻细胞生长良好,遗传稳定,培养后藻细胞密度和虾青素产量均与初代培养相近。研究结果对湖泊红球藻产虾青素工业藻株的选育具有实际意义。

     

pH-stat控制流加培养红发夫酵母产虾青素

通过酸碱流加培养、混合碳源-氨水流加培养、混合碳源-尿素流加培养等pH-stat控制流加培养红发夫酵母产虾青素。pH-stat控制流加培养与分批培养相比较,生物量及虾青素产量都有不同程度地提高。从提高虾青素产量和降低生产成本综合考虑,混合碳源-氨水流加培养是最理想的方法,培养96 h虾青素产量最高达到19.94 mg/L。     

微量营养素对玉米酵母流加培养的影响

文中研究了微量营养素的不同添加量对玉米酵母流加培养过程中糖液流加速率、溶氧量、酵母细胞浓度、酵母细胞生长率的变化,得出微量营养素的添加量为CaCl2 28.8mg/L,FeSO4 14.4mg/L,盐酸硫氨4.Smg/L,生物素0.12mg/L,D-泛酸钙6.4mg/L,肌醇120mg/L,玉米酵母细胞的产率提高了80.9％.     

虾青素保护视网膜色素上皮细胞免受蓝光发光二极管诱导的氧化应激损伤

目的：探究虾青素对蓝光发光二极管（light-emitting diodes,LED）诱导ARPE-19细胞氧化应激损伤的保护作用及其机制。方法：采用不同浓度的虾青素预处理细胞1 h后,蓝光LED下光氧化损伤诱导24 h。噻唑蓝法测定细胞活力,乳酸脱氢酶检测法分析细胞毒性,2’,7’-二氯二氢荧光素二乙酸酯荧光探针法测定细胞内活性氧（reactive oxygen species,ROS）的水平,JC-1荧光探针法测定细胞内线粒体膜电位的变化,利用酶学相关试剂盒测定细胞内源性抗氧化酶活力,实时荧光定量聚合酶链式反应法测定细胞内II相解毒基因的转录表达水平,Western blot法测定细胞内核因子E2相关因子2（nuclear factor erythroid-2-related factor 2,Nrf2）的核蛋白表达水平。结果：虾青素（5、10 μmol/L和20 μmol/L）预处理以浓度依赖的方式抑制蓝光LED诱导的ARPE-19细胞活力降低,缓解细胞毒性;虾青素预处理能够减少细胞内ROS的产生,稳定线粒体膜电位,提高内源性抗氧化酶活力。此外,虾青素诱导了Nrf2的核转位,增加了抗氧化酶和II相解毒基因的表达,从而保护ARPE-19细胞免受蓝光LED诱导的氧化应激损伤。结论：虾青素通过诱导Nrf2的核转位,促进抗氧化酶和II相解毒基因的表达水平升高从而保护ARPE-19细胞免受蓝光LED诱导的氧化应激损伤。     

Fed-batch coculture of Lactobacillus kefiranofaciens with Saccharomyces cerevisiae for effective production of kefiran

In a batch coculture of kefiran-producing lactic acid bacteria Lactobacillus kefiranofaciens and lactate-assimilating yeast Saccharomyces cerevisiae, lactate accumulation in the medium was observed, which inhibited kefiran production. To enhance kefiran productivity by preventing lactate accumulation, we conducted lactose-feeding batch operation with feedforward/feedback control during the coculture, so that the lactate production rate of L. kefiranofaciens was balanced with the lactate consumption rate of S. cerevisiae. The lactate concentration was maintained at less than 6 g l(-1) throughout the fed-batch coculture using a 5 l jar fermentor, although the concentration reached 33 g l(-1) in the batch coculture. Kefiran production was increased to 6.3 g in 102 h in the fed-batch coculture, whereas 4.5 g kefiran was produced in 97 h in the batch coculture. The kefiran yield on lactose basis was increased up to 0.033 g g(-1) in the fed-batch coculture, whereas that in the batch coculture was 0.027 g g(-1).