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。     

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%。     

利用毕赤酵母发酵废液培养原始小球藻的研究

以毕赤酵母发酵废液为水源并提供部分C源和N、P,在500 mL摇瓶中,比较了发酵废液培养基与SE基础培养基对原始小球藻的生长影响,并通过单因素和正交优化发酵废液培养基。结果表明,发酵废液培养基适合于原始小球藻的培养。利用发酵废液培养小球藻,在添加葡萄糖0.05 mol/L,硝酸钠0.01 mol/L,磷酸二氢钾0.003 mol/L,海绿素浓度300μL/L,培养7 d后最高生物量达6.56 g/L,油脂含量达33.68%,两者均高于SE基础培养基。油脂的脂肪酸组成分析表明,废液培养基培养下小球藻油脂的脂肪酸组成主要是C16∶0(25.12%)、C18∶0(4.69%)、C18∶1(50.46%)、C18∶2(6.78%)、C18∶3(8.58%),而SE培养基培养的小球藻油脂脂肪酸组成主要是C16∶0(24.56%)、C18∶0(20.36%)、C18∶1(16.66%)、C18∶2(14.32%)、C18∶3(30.98%),两种培养基培养所得藻油脂肪酸组成虽相差较大,但均适合作为生物柴油的原料。     

重要理化因子对小球藻生长和油脂产量的影响

本文采用通气培养的方法研究了N、P、Fe3 、盐度、光照强度、温度对小球藻(Chlorella sp. XQ-200419)生长速率、生物量和油脂产量的影响。主要结果如下：N浓度对小球藻的生长和油脂产量均有显著的影响,在KNO3浓度0.05—0.3g/L范围内,小球藻生长速率随N浓度的增加而提高,并积累更多的生物量,而油脂含量随之递减,KNO3浓度为0.3g/L时,油脂产量最高。小球藻对P浓度变化的适应范围很大,K2HPO4浓度在10—160mg/L范围内,对小球藻的生长和油脂产量都没有显著影响。在小球藻培养后期补加不同浓度Fe3 对其生长速率没有显著影响,总脂含量随着Fe3 浓度升高呈现上升的趋势,均比对照有极显著提高,Fe3 浓度为0.75mmol/L时油脂产量最高。盐度对小球藻的生长有一定的抑制作用;油脂含量先随着盐度的增大而提高,当NaCl浓度达到0.6mol/L, 油脂含量又显著降低;油脂含量和油脂产量均在盐度为0.2mol/L时最高。光照强度对处于生长后期的小球藻的生长影响不大,但影响其油脂积累,小球藻的油脂含量和产量随光照强度的增大而显著提高,当光照强度增至280μmolm-2s-1时,油脂含量和油脂产量最高。温度对小球藻的生长速率、生物量、油脂含量和油脂产量都有显著的影响,在15-40℃范围内,随着培养温度的升高,生长速率、生物量、油脂含量和油脂产量都经历了一个先上升然后下降的过程,适合小球藻生长、积累油脂的温度范围是20-35℃,30-35℃时油脂产量最高,40℃时生物量、油脂含量和产量都最低。理化因子对生长和油脂含量的影响分为两种情况：1. 温度、光强、铁浓度和盐度的影响表现为在适宜生长的条件下提高油脂含量,这种模式可以称为“适宜模式”;2. 氮浓度的影响表现为在不利于生长的条件下提高油脂含量,这种模式可以称为“胁迫模式”。两种模式都可以提高油脂含量,但是,只有适宜模式才可以提高油脂产量。在筛选小球藻优良产油藻种时要注意,只有在适宜的培养条件下油脂含量高的藻种才具有高产油潜力。     

均匀设计法优化蛋白核小球藻的异养培养基

[目的]通过优化培养基提高异养蛋白核小球藻CP9的生物量产率、蛋白质以及叶绿素含量。[方法]采用5因素8水平的均匀设计法优化小球藻异养培养基的配方,以葡萄糖、KNO_(3)、MgSO_(4)·7H_(2)O以及Fe-EDTA和CaCl_(2)母液为自变量,分析对小球藻生长、蛋白质含量和叶绿素含量的影响,来确定培养基自变量因素的最佳使用浓度。[结果]得到最佳培养基配方为:葡萄糖73.21 g/L、KNO_(3)6.25 g/L、MgSO_(4)·7H_(2)O 0.79 g/L、Fe-EDTA母液13.01 mL/L、CaCl_(2)母液4.80 mL/L。经培养基优化后将蛋白核小球藻CP9的最高细胞密度、蛋白质含量和叶绿素含量分别从11.08 g/L、43.3%和39.42 mg/g提升至15.08 g/L、60.0%和45.06 mg/g。[结论]通过正交优化蛋白核小球藻的异养培养基,将生物量提高了36%,同时藻细胞含有更高的蛋白质(60.0%)和叶绿素含量(45.06 mg/g),可为开发动物饲料或人类食品蛋白质。     

小球藻与固氮菌Mesorhizobium sp.共培养对小球藻生长和油脂积累的促进效果

微藻油脂不仅可以作为功能油脂,同时也是生产生物柴油的重要原料之一。为解决微藻生长与油脂积累之间的矛盾,利用藻菌共培养技术在缺氮条件下将无菌小球藻与细菌以不同初始比例进行共培养,通过测定藻细胞生物量、油脂含量和脂肪酸比例等来研究藻菌共培养对小球藻生长和油脂积累的影响。结果表明,在小球藻与固氮菌B2. 3 70∶1(V/V)共培养体系中,小球藻的生物量和油脂含量较同样条件下单独培养小球藻有了显著提高。其生物量最高可达1. 68g/L、总脂含量为45. 2%、总脂产率为75. 94 mg/(L·d)、中性脂含量为23. 0%及中性脂产率为38. 65mg/(L·d),其生物量和油脂含量分别较单独小球藻培养时提高了66. 3%和47. 7%。同时细菌的加入显著提高了藻细胞内C18∶1脂肪酸的比例。结论表明,通过藻菌共培养技术能够有效提高微藻生物油脂的质量和产量,具有较好的实际利用价值。     

小球藻高密度培养及油脂提取条件的优化

【目的】高密度培养小球藻及优化油脂提取条件。【方法】通过进行单因素实验研究不同培养基组成及环境因子对其细胞生长影响,并采用超声波提取法进行正交实验对藻粉油脂提取条件进行研究。【结果】对椭圆小球藻Y4进行异养培养,最适培养条件为:葡萄糖50 g/L,硝酸钾2 g/L,适宜的培养温度、摇床转速和接种量分别为29°C、180 r/min和20%。在此基础上,进行了1 L发酵罐培养实验,获得了干重18.25 g/L的生物量。通过对油脂提取条件进行优化,Y4的油脂提取率由优化前的25.0%提高到60.2%,提高了35.2%。【结论】优化了小球藻的培养条件及油脂提取条件,促进了小球藻的开发和利用。     

利用啤酒废水小球藻异养培养

摘要：【目的】利用小球藻异养培养技术处理啤酒废水,旨在为啤酒废水资源化利用和降低小球藻生产成本提供一个途径。【方法】在含有10 g/L葡萄糖的基本培养基进行异养小球藻高效藻株的筛选,并用于啤酒废水的资源化处理。【结果】从5株小球藻中得到2株适合高密度异养培养的藻株（Chlorella pyrenoidosa 15-2070 和 Chlorella vulgaris 15-2075）,在啤酒废水的资源化处理过程中这2株小球藻得到非常接近的试验结果。利用由废水配制含10 g/L葡萄糖的基本培养液培养Chlorella pyrenoidosa 15-2070获得了5.3 g/L藻细胞;并且在此过程中,啤酒废水得到有效利用,几种主要污染物最高去除率为：CODcr,92.2 %;BOD5,95.1 %;NO3--N,98.5 %;NH4+-N,92.3 %。【结论】啤酒废水中的重要环境污染物在培养小球藻的过程中可以得到有效地清除,并从中可以获得具有商业价值的小球藻细胞。     

2种小球藻在鱼糜加工废水处理过程中的生长和油脂积累规律

以小球藻Chlorella pyrenoidsa F-9和C.vulgaris HYS-2为材料,研究小球藻在鱼糜加工废水中的生长速率、脂类积累规律和对氮磷营养的消除效果。结果表明,2种小球藻在鱼糜加工废水中快速生长,最高生物量达到0.293 g/L和0.276 g/L,分别是f/2对照培养基的2.4和1.6倍。小球藻HYS-2在鱼糜加工废水中油脂百分含量最高达到36.22%,为对照培养基的1.27倍,小球藻F-9在鱼糜加工废水中的油脂含量达到17.89%,为f/2培养基中的0.89倍。培养15 d后,2种小球藻对鱼糜加工废水中氮磷去除率均达90%以上。以上研究表明,用未经任何化学处理的鱼糜加工废水养殖小球藻在生长速率上远远大于f/2培养基,说明其具有较好地发展潜力,可以实现微藻的低成本养殖。     

氮源对C.vulgaris油脂积累的影响

实验室条件下,考察了在发酵过程中不同氮源对小球藻的生物量和油脂积累的影响,确定了小球藻的最佳氮源;并对比分析了含氮培养与缺氮培养的生物量、油脂含量、氮消耗量、生物量氮消耗比率和油脂氮消耗比率的不同。结果表明:小球藻在1.6 g/L Na NO3时获得最大生物量,为562.2 mg/L,在0.8 g/L Na NO3时获得最大相对油脂含量为12.01%;以油脂含量为考察指标时,培养小球藻的最佳氮源为0.8 g/L Na NO3;缺氮培养时,最大油脂含量为13.49%,比含氮培养高约15%;含氮培养时,最高生物量为626.3 mg/L,比缺氮培养高约1.9倍。氮源对生物量,相对油脂含量,生物量氮消耗比率和油脂氮消耗比率具有明显的影响。藉此,提出了通过改变培养方式,达到调控小球藻细胞内生理代谢组分的可行性。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细