pH值对厚颌鲂幼鱼的耗氧率及窒息点的影响

在密封式流水呼吸室内,对厚颌鲂Megalobrama pellegrini幼鱼在pH值分别为5.5、6.0、6.5、7.0、7.5、8.0和8.5试验用水条件下的耗氧率进行了测定.结果 显示:厚颌鲂幼鱼耗氧率存在明显的昼夜变化,白天高于晚上,下午高于上午,夜间变化不大.不同pH值的平均耗氧率为0.7135 mg/g · h,平均耗氧率最高是在pH7.5时,为0.8665 mg/g · h,平均耗氧率最低是在pH5.5时,为0.5397 mg/g · h.在密封式呼吸室内测定pH值在5.5、6.0、6.5、7.0、7.5、8.0和8.5试验用水条件下的厚颌鲂幼鱼的窒息点,分别为1.3920、1.3067、1.1547、1.0683、1.0933、1.1733和1.2331 mg/L,平均窒息点为1.2008 mg/L.     

Effects of Temperature and pH on Cell Growth of a Flocculating Microalga (Chlorella vulgaris) JSC-7

微藻是可广泛用于健康食品及水产养殖的饵料,同时,微藻细胞内积累的油脂可作为可再生生物燃料,因此微藻的生长和代谢受到广泛关注。温度和pH对微藻的生物量积累有很大影响,考察不同温度和pH条件下微藻细胞的生长有助于寻找最佳的条件进行微藻的培养。自絮凝小球藻JSC-7（Chlorella vulgaris JSC-7）可实现自沉降采收,有利于降低微藻生产成本,优化其生长条件对更好地利用该微藻具有重要意义。考察了温度（22∽40℃）及pH（6.0∽10.0）对其细胞生长、叶绿素含量和油脂产量的影响。在所选取的温度及pH范围内,JSC-7细胞均可生长,显示该藻种可以适应广泛的温度和pH条件。适合细胞生长的温度依次为31℃〉28℃〉35℃〉25℃,pH依次为7.0〉8.0〉6.0。pH 8.0时生物量和油脂的积累量最多,说明该藻株在弱碱条件下更适合生长和产油。当温度为31℃、pH为7.0时,可获得最高的生长量（OD690=0.941）、叶绿素含量（19 mg/L）及油脂产量（39.07%/克干重）。     

热带普通小球藻培养模式的筛选及其培养基的优化

【背景】从海南热带海区中分离得到一株微藻,其生长速度快、适应力强,经鉴定该微藻为普通小球藻。【目的】提高热带普通小球藻的生长速率。【方法】以"宁波大学3#微藻培养液配方"为基础培养液,分别添加有机碳(C6H12O6和CH3COONa)对热带普通小球藻进行自养、兼养及异养培养,获得促进热带普通小球藻快速生长的培养方式。在"宁波大学3#微藻培养液配方"的基础上对热带普通小球藻的兼养培养基配方进行优化,并用优化兼养培养基与"宁波大学3#微藻培养基"对比培养热带普通小球藻。【结果】添加6 g/L CH3COONa的兼养模式促进热带普通小球藻生长效果最好;优化的兼养培养基配方为:6 g/L CH3COONa,20 mg/L(NH4)2SO4-N,5 mg/L Na H2PO4-P,3 mg/L Fe SO4-Fe,1 mg/L Vitamin B1和0.000 5 mg/L Vitamin B12。对比培养实验结果显示,培养第6天,兼养培养液收获的生物量(细胞密度)达4.20×107 cells/m L,是"宁波大学3#配方微藻培养液"的2.30倍。【结论】兼养培养模式为热带普通小球藻的最佳培养模式,优化的兼养培养基极显著地提高了热带普通小球藻的生物量(P0.01)。     

无机碳源对小球藻自养产油脂的影响

旨在研究小球藻利用无机碳自养产油脂,考察了3种无机碳源 (Na2CO3、NaHCO3和CO2) 及其初始浓度对小球藻产油特性的影响。结果表明,小球藻能利用Na2CO3、NaHCO3和CO2产油;经Na2CO3、NaHCO3和CO2培养10 d后,随着每种无机碳源浓度的增加,小球藻产量均先增加后减少。小球藻经3种无机碳源培养后,其培养液pH值上升。最适宜的Na2CO3和NaHCO3添加量均为40 mmol/L,其生物量分别达到0.52 g/L和0.67 g/L,产油量分别达到0.19 g/L和0.22 g/L。在3种无机碳源中,CO2是最佳无机碳源,当CO2浓度为6％时,小球藻生长最快,生物量达2.42 g/L,产油量最高达0.72 g/L;当CO2浓度过低时,无机碳供应不足,油脂产量低;当CO2浓度过高时,培养液pH偏低,小球藻油脂积累受到抑制。Na2CO3和NaHCO3较CO2更有利于小球藻积累不饱和脂肪酸。     

不同培养基及组成对2种小球藻生长和油脂的影响

研究了4种培养基及组成对蛋白核小球藻F-9和普通小球藻HYS-2的生长、油脂积累和脂肪酸组成的影响。结果发现knop、Provasoli、f/2、MAV 4种培养基中,f/2培养基更有利于小球藻的快速生长,而MAV培养基更适合油脂积累。在f/2培养基中F-9和HYS-2相对生长速率分别为0.156和0.171,培养9 d细胞干重为0.188 g/L和0.195 g/L。而在MAV培养基中F-9油脂含量最高可达19.67%,HYS-2油脂含量最高为21.91%,脂肪酸最高分别占干重的5.11%和8.71%。N/P为16∶1时小球藻生长最快,培养9 d后F-9和HYS-2的相对生长速率分别为0.23和0.239,最终细胞干重分别为0.107 g/L和0.143 g/L。而F-9和HYS-2在N/P为1∶1条件下积累油脂和脂肪酸含量最高,总脂含量分别占干重的为20.40%和27.39%,总脂肪酸占藻粉干重的含量为12.52%和16.94%。     

蛋白核小球藻发酵产油脂的研究

从5种不同来源的小球藻中筛选到1株油脂产量较高的蛋白核小球藻Chlorella pyrenoidosa No.2。研究了培养基组成及培养条件对其细胞生长和油脂积累的影响。结果表明, 最适培养基组成为(g/L)：葡萄糖 20, 甘氨酸 0.08, MgSO4·7H2O 0.4, K2HPO4 1.0, FeSO4·7H2O 0.004; 适宜的培养温度、初始pH、摇床转速和光照强度分别为28℃、6.0、130 r/min和 650 Lux。在上述优化条件下培养7 d, Chlorella pyrenoidosa No.2的生物量和油脂含量分别由优化前的3.73 g/L 和 40.15%提高到6.56 g/L和59.90%, 油脂产量提高了162%。Chlorella pyrenoidosa No.2能以木糖为碳源产油脂, 可望用于以木质纤维素等可再生生物质资源为原料生产油脂。气相色谱分析表明该油脂的脂肪酸组成与植物油相似, 不饱和脂肪酸含量达71％左右, 可作为生产生物柴油的原料。     

吲哚美辛调控小球藻生长及代谢的初步研究

本研究通过在小球藻培养液中添加不同浓度的吲哚美辛(0mg/L,50mg/L,75mg/L,100mg/L,112.5mg/L,125 mg/L,150 mg/L)来研究其对小球藻生长及代谢的影响,并探索其影响机制。研究表明:吲哚美辛对小球藻生长和代谢的影响与其浓度有关,低浓度吲哚美辛(≤75 mg/L)可促进小球藻的生长,而高浓度(≥100 mg/L)则会抑制其生长,且在75 mg/L处理组中,吲哚美辛对小球藻生长的促进作用最明显,培养液p H值的变化最小,小球藻可溶性糖含量最高(3.12μg/106 cells)。而在高浓度(150 mg/L)处理组中,吲哚美辛可显著促进小球藻细胞内叶绿素a和可溶性蛋白的积累,可分别达到0.38μg/10~6 cells和7.09μg/106 cells,油脂含量也相对于对照组提高了60%。研究将为探索吲哚美辛调控小球藻生长及代谢的作用机制提供理论基础和技术资料,也将为小球藻的产业化培养及其代谢产物的调控提供思路。     

蛋白核小球藻发酵产油脂的研究

从5种不同来源的小球藻中筛选到1株油脂产量较高的蛋白核小球藻Chlorella pyrenoi-dosa No.2.研究了培养基组成及培养条件对其细胞生长和油脂积累的影响.结果表明,最适培养基组成为(g/L):葡萄糖20,甘氨酸0.08,MgSO4·7H2O 0.4,K2HPO4 1.0,FeSO4·7H2O 0.004;适宜的培养温度,初始pH、摇床转速和光照强度分别为28℃、6.0、130 r/min和650 Lux.在上述优化条件下培养7 d,Chlorella pyrenoidosa No.2的生物量和油脂含量分别由优化前的3.73 g/L和40.15%提高到6.56 g/L和59.90%,油脂产量提高了162%.Chlorella pyrenoidosa No.2能以木糖为碳源产油脂,可望用于以木质纤维素等可再生生物质资源为原料生产油脂.气相色谱分析表明该油脂的脂肪酸组成与植物油相似,不饱和脂肪酸含量达71%左右,可作为生产生物柴油的原料.     

硫和pH对蛋白核小球藻光照产氢的影响

在有无硫及pH5.0-8.0下对蛋白核小球藻(Chlorella pyrenoidosa)光照产氢的影响进行了研究。结果表明,在持续光照(165μmolm-2s-1)条件下,从有硫培养液(TAP培养液)内叶绿素a含量、Fv/Fm值及ΦPSII值的变化表明蛋白核小球藻在pH6.0-7.0时生长最佳,生长旺盛易形成暂时的无氧环境而利于藻产氢。最高的产氢速率和总产氢量出现在pH7.0,分别是0.10mlmg-1chlh-1和1.39ml。从无硫培养液(TAP-S培养液)内叶绿素a含量、Fv/Fm值及ΦPSII值的变化表明蛋白核小球藻生长明显受抑制,形成的无氧环境持久,故产氢持久,总产氢量比有硫培养液内高。蛋白核小球藻在pH5.5培养液内的Fv/Fm值后期高于其他4种pH值的,表明潜在的PSII光化学效率高,在光照条件下产氢电子主要来源于PSII,故pH5.5的无硫培养液内藻的产氢速率和总产氢量最大,分别是0.58mlmg-1chlh-1和10.98ml。说明pH为5.5的无硫培养液是蛋白核小球藻产氢的最佳条件。     

温度及pH对自絮凝小球藻JSC-7生长的影响（英文）

微藻是可广泛用于健康食品及水产养殖的饵料,同时,微藻细胞内积累的油脂可作为可再生生物燃料,因此微藻的生长和代谢受到广泛关注。温度和pH对微藻的生物量积累有很大影响,考察不同温度和pH条件下微藻细胞的生长有助于寻找最佳的条件进行微藻的培养。自絮凝小球藻JSC-7(Chlorella vulgaris JSC-7)可实现自沉降采收,有利于降低微藻生产成本,优化其生长条件对更好地利用该微藻具有重要意义。考察了温度(22~40℃)及pH(6.0~10.0)对其细胞生长、叶绿素含量和油脂产量的影响。在所选取的温度及pH范围内,JSC-7细胞均可生长,显示该藻种可以适应广泛的温度和pH条件。适合细胞生长的温度依次为31℃28℃35℃25℃,pH依次为7.08.06.0。pH 8.0时生物量和油脂的积累量最多,说明该藻株在弱碱条件下更适合生长和产油。当温度为31℃、pH为7.0时,可获得最高的生长量(OD690=0.941)、叶绿素含量(19 mg/L)及油脂产量(39.07%/克干重)。     

Effects of o-cresol co-disposal and pH on the methanogenic degradation of refuse

SULISTI, I.A. WATSON-CRAIK AND E. SENIOR. 1996. Both maximum o -cresol degradation and activity of sulphate-reducing bacteria (SRB) were observed at refuse pH values between 7.0 and 8.0. Optimum pH values for methane release were between 6.5 and 7.5. Partial inhibition of methane production was recorded at pH 5.7, 6.0 and 8.0, whilst sulphate reduction was inhibited partially at pH values 5.7–6.5. Both sulphate reduction and methanogenesis were completely inhibited in refuse with initial pH 4.0. The catabolism of acetate occurred under similar conditions to methane production, and was promoted at pH 6.5–7.5. It appeared that propionate oxidation depended upon the activities of SRB. Optimum conditions for the metabolism of propionate and other volatile fatty acids were between pH 7.0 and 8.0.     

Effect of propionate toxicity on methanogenesis of night soil at phychrophilic temperature

The effect of propionate concentrations on biodegradation of human waste (night soil) was studied at 10 degrees C. Propionate was toxic for the biomethanation at all the pH tested (6.0, 7.0 and 8.0). The maximum reduction in biogas production in presence of 200 mM propionate was observed at pH 7.0 followed by 8.0. The methane content in biogas also followed a similar trend and at pH 7.0 an 11.5% decrease was observed. Propionate caused the reduction of methanogenic count by an approximately 2log value. Total volatile fatty acids increased with the increase in propionate concentration and particularly accumulation of propionate was observed. The results were also compared with the 30 degrees C fermentation.     

The effect of pH on hydrogen production with Citrobacter intermedius

Summary Citrobacter intermedius was grown in a 14-liter fermenter under batch anaerobic conditions at the following controlled pH values: 5, 5.75, 6.0, 6.5, 7.0, 7.5, and 8.0. The growth medium was a glucose mineral salts medium with 0.1% ammonium sulfate as the source of sulfur. The optimum pH for H₂ production was 5.75 and 6.0 which gave a yield of 1.1 moles H₂/mole glucose. The optimum H₂-productivity was 144 moles H₂ per hour at pH 6.0.     

Identification of a pH 6.5 acetohydroxyacid synthetase inBacillus subtilis

Acetohydroxyacid synthetase activity of crude extracts ofBacillus subtilis grown in pH 7.0 minimal medium has a pH optimum of 7.5. However, the activity of extracts of cells grown in minimal medium of pH 6.0 shows a pH optimum of 6.5. Acetate or propionate induces formation of the pH 6.5 activity. Hydroxyapatite chromatography of a crude extract of cells grown in pH 7.0 medium shows one major and one minor peak of enzymatic activity. Both peaks have a pH optimum of 7.5–8.0. However, chromatography of an extract of cells grown in the presence of acetate reveals three peaks of activity: one major peak with a pH optimum of 6.5 and two minor peaks both having a pH optimum of 7.5–8.0.     

甜瓜幼苗生长及光合特性与育苗基质pH相关性研究

以新疆厚皮甜瓜皇后为试材,在泥炭珍珠岩复合基质中,按一定比例加入CaCO3,构成pH梯度值分别为5.0、5.5、6.0、6.5、7.0、7.5和8.0的7种基质类型,研究了基质pH对甜瓜幼苗生长及其光合特性的影响。结果表明,基质酸碱性对甜瓜幼苗的光合特性、根系活力、单株叶面积、根系和地上部干物重都产生显著影响,酸性和微酸性基质(pH<6.0)时,幼苗叶片叶绿体超微结构发生降解,叶绿素堆积,叶片净光合速率下降,单株叶面积减小,根和地上部干重降低;pH为6.0～7.0的各处理在叶面积以及根和地上部干重指标上,F检验不显著;pH>7.0的微碱性和碱性基质虽然对幼苗产生不利影响,但与pH<6.0的处理比较,其影响要小些。鉴于此,甜瓜幼苗生长的基质pH范围为6.0～7.0,偏碱不会对幼苗产生严重的生理障碍。采用CaCO3调节基质pH时,最佳调节范围为pH6.0～6.5。     

Low velocity gradient flow birefringence and viscosity changes in hyaluronate solutions as a function of pH.

The flow birefringence and extinction angle over a velocity gradient range of approximately 5–100 sec^?1, and the zero shear-viscosity have been obtained from human umbilical cord hyaluronic acid at concentrations of 0.25, 0.125 and 0.0625%, and pHs 6.0, 6.5, 7.0, 7.5, 8.0, and 8.5 and constant ionic strength 0.1. The data indicate a large change in optical anisotropy as a function of pH, with most of the transition in the pH range 7.0–7.5, i.e., across the physiological range. The sign of the anisotropy changes between pH 8.0 and 8.5. These results, together with changes in the extinction angle and intrinsic viscosity as a function of pH, suggest a pH-dependent structural change in the system. Due to the abruptness of the transition, as evidenced by the intrinsic viscosity and flow birefringence, it is probable that the structural transition is cooperative. If the data are interpreted in terms of the Rouse-Zimm Gaussian subchain theory, a modification of the model in terms of the Haller-Cerf concept of internal viscosity is required. Thus, the demonstrated properties of hyaluronate solutions indicate a system with memory of stress. Due to the presence of large concentration effects discernible in the extinction angle measurements, hyaluronic acid probably exists as a network in solution. The results are discussed with respect to the mechanoelectrical transducing properties of hyaluronates and stress-dependent changes in ORD already reported.     

半连续及连续培养小球藻减排沼液及CO2

采用半连续或连续模式培养小球藻,考察小球藻减排沼液和CO2的能力。结果表明:在半连续培养模式中,当更新率为30%时,沼液中的N、P质量浓度可分别稳定在16～18和0.4～0.6 mg/L,达到污水二级排放标准;提高更新率到40%以上,3 d后微藻生物量及其对沼液中N、P的吸收达到动态平衡,但N、P去除率未达到污水直接排放标准;在连续培养模式中,分别选用20%及30%的日更新率,7 L规模12 d后沼液中的总氮(TN)仍高达55.64 mg/L。说明大规模培养条件下的光限制是微藻法减排沼液的主要制约因素。     

Effect of pH on malonyl-CoA inhibition of carnitine palmitoyltransferase I.

Malonyl-CoA inhibition of carnitine palmitoyltransferase I was found to be very pH-dependent. Malonyl-CoA concentrations causing 50% inhibition (I50) at pH 6.0, 6.5, 7.0, 7.5 and 8.0 were 0.04, 1, 9, 40 and 200 microM respectively. It is suggested that a lowering of intracellular pH, such as might occur in ketoacidosis, may attenuate hepatic fatty acid oxidation by increasing malonyl-CoA sensitivity of carnitine palmitoyltransferase I.