硫代硫酸钠及葡萄糖对蓝细菌Synechocystis sP.PCC6803脂及光合器组成的影响

本文通过对蓝细菌Synechocystis sp. PCC 6803在添加葡萄糖、Na2S203的BG-11培养基中的生长特性、脂类及脂肪酸组成、细胞低温荧光、色素组成进行分析测定，总结出如下规律： 当蓝细菌Synechocystis sp. PCC 6803在添加有葡萄糖的BG-11培养基中培养时细胞出现了一种新的糖脂（记为糖脂-x），在添加果糖、麦芽糖、乳糖等其它碳源的培养基中生长的细胞中也检测到糖脂-x糖脂-x的出现经推测是与活性氧相作用的产物，当在含糖的培养基中加入活性氧猝灭剂Na2S203时能有效地抑制糖脂-x的出现。糖脂一x的出现伴随着其它脂、尤其是双半乳糖甘油二酯(DGDG)的含量下降，这可能与细胞营养代谢类型的转变相适应。糖脂-x的出现使细胞适应异养生长条件，这时藻胆体(PBS)，光系统II(PSII)，光系统I(PSD降解，叶绿素消失。 糖脂-x经1H-NMR波谱术检测证实为甘油糖脂，经气质联谱分析其脂肪酸组成中含大量的枝链脂肪酸，12-甲基十四碳酸、12-甲基十五碳酸、12-甲基十六碳酸以及两种稀有的含氮脂肪酸。这些脂肪酸在添加高浓度葡萄糖的培养基中生长的．Synechocystis sp. PCC 6803中的单半乳糖甘油二酯(MGDG)也能检测到。ESI-MS以及P-SI-MS测定结果表明糖脂．x含一分子的脂酰基侧链以及两分子的己糖，半乳糖与葡萄糖。 对．Synechocystis sp. PCC 6803生长在不同浓度的葡萄糖与Na2S203培养基中脂类组成与脂肪酸组成进行比较，发现Na2S203能有效地增加膜脂中硫代异鼠李糖二酰基甘油(SQDG)和磷脂酰甘油(PG)的百分含量，培养基中同时添加葡萄糖时能抵消Na2S203的这一效应。此外，Na2S203能显著增加单半乳糖甘油二酯(MGDG)、双半乳糖甘油二酯(DGDG)中十六碳酸(C16:0)的百分含量，这一效应也能为葡萄糖恢复。Na2S203不能显著地改变SQDG中C16:0的百分含量，加入葡萄糖时能降低C16:0的百分含量。这些结果说明Na2S203可能充当一种还原剂使膜脂处于一种低的不饱和状态，同时加入葡萄糖时能降低Na2S203的还原力。此外，Na2S203还可作为SQDG合成中的硫供体。 用HPLC测定．Synechocystis sp. PCC 6803在添加不同浓度的Na2S203，葡萄糖的BG-11培养基中生长时的叶绿素与类胡萝卜素浓度，结果表明葡萄糖表现出对叶绿素与类胡萝卜素水平的抑制效应，Na2S203在低浓度时表现出对叶绿素与类胡萝卜素水平的促进效应，但在高浓度时表现出抑制效应。因此适当浓度的Na2S203的加入有利于维持蓝细菌在培养基中添加葡萄糖的生长条件下的低水平自由基，能使葡萄糖表现出促进细胞生长的特性。 通过测定Synechocystis sp. PCC 6803生长曲线中葡萄糖、Na2S203的浓度效应，结果表明葡萄糖在低浓度（例如5 mmoI.L-l）时表现出促进细胞的生长，在相对高的浓度表现出抑制细胞生长的效应。在培养基中同时加入Na2S203时可恢复葡萄糖对细胞的生长的促进效应。单独加入Na2S203表现出对细胞生长的抑制效应。这说明葡萄糖、Na2S203对细胞的生长存在着正的协同效应。

海洋小球藻Chlorella sp.甘油脂及脂肪酸、光合色素特征的研究

海洋微藻是海洋生态系统中最主要的初级生产者，也是海洋生物资源的重要来源。许多海洋微藻富含对人体具有重要的生理作用与保健功能的长链多不饱和脂肪酸，因此，筛选富含EPA、DHA等长链多不饱和脂肪酸的微藻和利用人工培养方法提高这些脂肪酸的产量是当前海洋生物学研究领域的热点之一。在本研究中，我们对被中科院海洋所定名为“Chlorella sp���（编号为1061）的一种海洋微藻的化学分类、甘油脂及其脂肪酸组成和外源葡萄糖和抗氧化剂（硫代硫酸钠）对这种微藻的脂肪酸含量的影响进行了研究，取得了以下主要结果。 海洋微藻是我固海水养殖中广泛使用的优良饵料藻。脂类物质是微藻最重要的营养指标之一，在本研究中，我们首先分析了被中科院海洋所定名为“Chlorellasp���的海洋微藻中的甘油脂及其脂肪酸种类和组成特点。结果表明，Chlorella sp.中的非极性脂主要为三脂酰甘油，极性甘油脂有10种。其中，一般培养条件下（温度23℃：光照，周期L/D14:10，强度60umolm-2-S-l）三脂酰甘油约占总脂的31 mol%，极性甘油脂约占总脂的69 rriol%。10种极性甘油脂是单半乳糖甘油二脂( monogalactosyldiacylglycerol． MGDG)、 双半乳糖甘油二脂( diagalactosyldiacylglycerol ， DGDG)、 硫代异鼠李糖甘油二脂( sulfoquinovosyldiacylglycerol，SQDG)、磷脂酰甘油(phosphatatidylglycerol，PG)、磷脂酰乙醇胺(phosphatidylethanolamine，PE)、磷脂酰胆碱( phosphatidylcholine，PC)、磷脂酰肌醇(phosphatidylinositol，PI)、磷脂酰丝氨醴(phosphatidylserine，Ps)、l，2-二酰基甘油-0-4，．（ⅣMⅣ-三甲基）高丝氨酸（diacylglyceryltrimethylhomoserine，DGTS）以及一种未能完全肯定，但可能是一中氯硫脂( chlorosulfolipid，CSL)。其中MGDG、DGDG、SQDG和PG是构成光合膜的主要成分，也是Chlorella sp���的主要极性脂。甜菜碱脂DGTS和磷脂PC是构成非光合膜的主要组分。Chlorella sp.中的主要脂肪酸为C16:0、C16:1耜C20：5（EPA)，后者主要存在于MGDG、DGDG和DGTS中，而三脂酰甘油也含有接近7%的EPA。 海洋微藻Chlorella sp.1061虽然被归属到绿藻纲绿藻目小球藻属，但是我们的研究表明，其色素、极性脂皮其脂肪酸组成与其它小球藻属藻类存在这很大差异Chl b是绿藻纲藻类中最主要的光合色素之一，1 6：4(n-3)和l 8：3(n-3)是绿藻微藻的主要脂肪酸，然而所有这些绿藻的特征化合物均未在Chlorella sp. 1061中检测到。DGTS和20:5(n-3)存在于很多的海洋微藻中，我们从Chlorella sp. 1061 中分离到占总极性甘油脂8 mo1%的DGTS，并从MGDG、DGDG和DGTS等极性甘油脂中检测到大量的20:5(n-3)。但是一般认为，小球藻属藻类中不舍这两种化合物。根据Chlorella sp. 1061的以上特点，这种藻不应该被归到小球藻属中。另外，由于Chlorella sp. 1061在色素、膜脂和脂肪酸组成特征方面大眼藻纲( Eustigmatophyceae)中的微绿球藻（Nannochloropsis）非常相似，因此，我们认为ChloreHa sp. 1061可能是Nannochloropsis中的一个种。但是未得到更进一步的证明和权威的认可之前，本文中我们仍然沿用ChloreHa sp,这一名称。 许多藻类中DGTS和PC -般不会同时存在，或者说一个存在时另外的一个的含量非常低。由此有人认为DGTS和PC之间存在着相互替代的关系。然而本研究中发现正常培养条件下Chlorella sp.中的DGTS和PC含量均较高（约10%）。磷处理实验结果表明，磷缺乏时Chlore Ha sp,中DGTS舍量大幅升高，而同时PC含量相应下降许多：但高浓度的磷并不能提高PC含量和降低DGTS含量，说明Chlorella sp,中DGTS仍可起替代PC的作用，然而PC可能并不能替代DGTS。Chlorella sp.中MGDG和DGTS脂肪酸组成及其位置分布结果显示，它们的组成和分布相似;在老化培养过程中MGDG和DGTS表现出周期性的相反的含量升高、降低的趋势，这进一步说明MGDG和DGTS之间存在着特殊的关系，MGDG可能合成自DGTS。 海洋微藻富含有利于人体健康的长链不饱和脂肪酸，如何提高微藻脂肪酸特别是多不饱和脂肪酸产量是目前研究的热点之一。本文首次报道了同时加入葡萄糖和硫代硫酸钠对Chlorelta sp,的生长、脂类组成和脂肪酸总产量的影响，结果显示葡萄糖和硫代硫酸钠存在明显而且强烈的互作，二者在培养液中的同时存在显著刺激了脂肪酸总产量的积累，在培养液中分别加入2.5 mM的葡萄糖和5mM的硫代硫酸钠，脂肪酸的产量可以比对照提高78%。而低浓度的葡萄糖和硫代硫酸钠对Chlorella sp.脂肪酸组成影响变化不明显，甚至在硫代硫酸钠存在下令人感兴趣的EPA含量还略有升高。显然，在Chlorella sp.培养中同时加入低浓度的葡萄糖和硫代硫酸钠是极具潜力的提高脂产量的方法，也可作为提高培养微藻其它活性物质产量借鉴的方法。在不久的将来，这种培养方法很可能发展成为生产实践中提高Chlore sp���乃至其它微藻脂肪酸、EPA和其它活性物质产量的经济有效的新途径。

Chryseobacterium flavum sp nov., isolated from polluted soil

A Gram-negative, non-motile, rod-shaped bacterial strain, designated CW-E 2(T), was isolated from a polluted soil sample collected from Jiangsu Province, China. A taxonomic study of the isolate, including phylogenetic analysis based on 16S rRNA gene seque

Pontibacter akesuensis sp nov., isolated from a desert soil in China

A Gram-negative, non-motile, rod-shaped bacterium, designated strain AKS 1 T, was isolated from a desert soil sample collected from Alkesu, Xin.lang Province, China. A taxonomic study, including phylogenetic analysis based on 16S rRNA gene sequences and p

Bacillus pallidus sp nov., isolated from forest soil

A Gram-positive bacterium, designated strain CW 7(T), was isolated from forest soil in Anhui Province, south-east China. Cells were strictly aerobic, motile with peritrichous flagella and rod-shaped. The strain grew optimally at 30-37 degrees C and pH 7.0-8.0. The major fatty acids of strain CW 7(T) were anteiso-C-15:0, iso-C-15:0 and anteiso-C-17:0. The predominant menaquinone was MK-7. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The G + C content of the genomic DNA was 42.3 mol%. Phylogenetic analysis indicated that strain CW 7(T) belonged to a monophyletic cluster within the genus Bacillus and showed 16S rRNA gene sequence similarities of less than 96.5% to recognized species of the genus Bacillus. The results of the polyphasic taxonomic study, including phenotypic, chemotaxonomic and phylogenetic analyses, showed that strain CW 7(T) represents a novel species of the genus Bacillus, for which the name Bacillus pallidus sp. nov. is proposed. The type strain is CW 7(T) (=KCTC 13200(T)=CCTCC AB 207188(T)=LMG 24451(T)).

Pseudomonas duriflava sp nov., isolated from a desert soil

A Gram-negative, rod-shaped, non-motile, non-spore-forming bacterium, designated strain HR2(T) was isolated from a soil sample from the Talklimaken Desert in Xinjiang Province, China. Strain HR2(T) grew optimally at pH 7.0-8.0 and 30-37 degrees C in the presence of 0-1% (w/v) NaCl. An analysis of 16S rRNA gene sequences revealed that strain HR2(T) fell within the radiation of the genus Pseudomonas, the highest level of similarity being found with respect to Pseudomonas luteola IAM 13000(T) (97.5%); the levels of sequence similarity with respect to other recognized Pseudomonas species were < 96.4%. DNA-DNA hybridization showed that the genetic relatedness between strain HR2(T) and P. luteola IAM 13000(T) was 53.2%. The G + C content of the genomic DNA of strain HR2(T) was 55.2 mol%. The major fatty acids were 18: 1, summed feature 3 and 16:0. The hydroxylated fatty acids 10:0 3-OH, 12:0 3-OH and 12:0 2-OH were also present. The data obtained in this polyphasic study indicated that this isolate represents a novel species of the genus Pseudomonas, for which the name Pseudomonas duriflava sp. nov. is proposed, The type strain is HR2(T) (=KCTC 221129(T) =CGMCC 1.6858(T)).

Sphingobacterium siyangense sp nov., isolated from farm soil

The taxonomic position of a novel Gram-negative strain, designated Sy1(T), isolated from a farm-soil sample obtained from Jiangsu Province, PR China, was characterized by using a polyphasic approach. The cells were non-motile, non-spore-forming rods. The organism grew optimally at 30-37 degrees C and at pH 6.0-8.0. Based on 16S rRNA gene sequence analysis, strain Sy1(T) is a member of the genus Sphingobacterium; Sphingobacterium multivorum JCM 21156(T) was the nearest relative (98.5% sequence similarity). The predominant fatty acids of strain Sy1T were isoC15:0 (32.90/o), C16:0 (10.9%) and summed feature 3 (iso-C-15:0 2-OH and/or C-16:1 omega 7c; 24.1%). The DNA G + C content was 38.5 mol%. The low level of DNA-DNA relatedness (2.2 %) to S. multivorum JCM 21156 T in combination with differential morphological and biochemical properties demonstrated that strain SY1(T) (=KCTC 22131(T)= CGMCC 1.6855(T)) should be classified as representing a novel species of the genus Sphingobacterium for which the name Sphingobacterium siyangense sp. nov. is proposed.

Heterorhabditidoides chongmingensis gen. nov., sp nov (Rhabditida : Rhabditidae), a novel member of the entomopathogenic nematodes

During a recent soil sample survey in Eastern China, a new entomopathogenic nematode species, collected from the Chongming Islands in the southern-eastern area of Shanghai, was discovered. Morphological characteristics of different developmental stages of the nematode combined with molecular data showed that this nematode is a new genus of Rhabditidae, and described as Heterorhabditidoides chongmingensis gen. nov., sp. nov., for that it shares more morphological characteristics with heterorhabditids than with ste-inernematids. For males, the papillae formula of bursa is 1, 2, 3, 3, with constant papillae number in the terminal group, stoma tubular-shaped and about 1.5 head width; cheilorhabdions cuticularized, esophageal collar present and long, median bulb present. For infective juveniles, EP = 90 (80-105) mu m, ES = 104 (92-120) mu m, tail length = 111 (89-159) mu m, and a = 19.1 (15-21). The percentages of the nucleotides A, T, C and G in the ITS1 regions of the new species are significantly different from those of heterorhabditids and other rhabditids. Molecular phylogenetic trees based on 18S rDNA and the internal transcribed spacer (ITS) sequences data revealed that the new entomopathogenic nematode species forms a monophyletic group, which is a sister group of the clade comprised of some genera of Rhabditidae. (c) 2008 Elsevier Inc. All rights reserved.