有机磷农药对铜绿微囊藻生长及摄磷效应的动力学研究

研究了两种有机磷农药 (甲胺磷、辛硫磷 )在较低浓度时对铜绿微囊藻的生长效应以及微囊藻摄取磷形态 :总溶解磷 (TSP)、溶解反应磷 (SRP)和溶解有机磷 (DOP)的动力学规律。保持各培养基中总磷的浓度 6 95mg/L ,与培养基中不加有机磷农药相比 ,当培养基中甲胺磷与K2 HPO4的浓度比为 1∶11和 1∶9,辛硫磷与K2 HPO4的浓度比为1∶349和 1∶114时 ,微囊藻的生长受到促进 ,并且当甲胺磷与K2 HPO4,的浓度比为 1∶9,辛硫磷与K2 HPO4的浓度比为1∶114时促进效果最好 ,而当培养基中没有K2 HPO4甲胺磷作为惟一磷源时 ,微囊藻的生长受到明显的抑制。微囊藻摄取SRP的速度快于其他磷形态 ,而对DOP的利用较少。微囊藻生长越快 ,对SRP的摄取速率也越快。结果表明低浓度有机磷农药促进微囊藻生长的主要原因是有机磷的加入促进了藻类对SRP的摄取     

磷浓度对铜绿微囊藻、大型溞和金鱼藻三者相互作用的影响

为了解磷浓度对生物操纵和水生植被恢复效果的影响,以铜绿微囊藻、大型溞和金鱼藻分别作为浮游植物、浮游动物和大型沉水植物的代表,在25℃、2000—3000lx光强和11mg/L氮浓度条件下,研究两者和三者共培养时4种磷浓度(0.2、0.5、1.0、1.5 mg/L)下各自的增长率和培养液中氮磷去除率的变化。结果表明:两者共培养时,磷浓度不大于0.2mg/L时,有利于大型溞的繁殖和金鱼藻的生长;磷浓度介于0.5—1.5mg/L时,铜绿微囊藻呈正增长趋势,而金鱼藻的生长则明显受抑制。三者共培养时,所有磷浓度下的大型溞数量及金鱼藻生物量均不同程度的升高,且铜绿微囊藻的生长得到了有效抑制,以磷浓度为0.2—0.5mg/L时效果最佳;N/P比值对藻、溞、草间的相互作用有重要影响,在藻-溞系统中,大型沉水植物的加入可以大大提高抑藻效果,减小N/P比值波动带来的不利影响。磷浓度为0.5mg/L时的水体氮磷去除效果好于其他磷浓度梯度。     

富营养化水体中N、P浓度对浮游植物生长繁殖速率和生物量的影响

在浮游植物生长繁殖的高峰期（7—10月份）对3个富营养化水体的总氮、总磷和浮游植物生物量进行调查,统计分析了生物量与氮和磷浓度的关系。利用3种水样和梯度稀释的东湖水样培养玫瑰拟衣藻（Chloromonas rosae）,研究了氮、磷浓度对生长繁殖速率的影响。结果表明磷是生长繁殖速率的限制因子,求出了生长繁殖速率与磷浓度的对数回归方程y=0．08061nx＋0．4658,当磷浓度小于0．05mg／L时,生长繁殖速率随着磷浓度的升高而直线上升,当磷浓度进一步升高,生长繁殖速率仍然随之增加,但增加的幅度越来越小,当磷浓度达到0．2mg／L时,生长繁殖速率基本不再随着磷浓度的增加而升高。计算出生长速率为零时磷的浓度是0．003mg／L,接近贫营养化湖泊磷浓度的下限,计算结果与坂本的调查统计结果相吻合,说明回归方程具有代表性。在凋查的3个富营养化水体中,浮游植物中的氮占全部氮元素的53％,磷占全部磷元素的85％,是氮、磷存在的主要形式,所以,评价水体的营养程度,必须同时考虑水中溶解的氮、磷和生物体内的氮、磷。统计分析表明,3个富营养化水体中浮游植物的生物量由氮（溶解氮＋胞内氮）和磷（溶解磷＋胞内磷）的浓度共同决定,生物量与氮浓度的直线回归方程y=10．687x-7．8304,生物量与磷浓度的直线回归方程y=122．11x-12．069。实验结果为根据氮、磷浓度以Redfield值判断浮游植物限制性营养元素的相对性和绝对性提供了例证。对3个富营养化水体的比较表明,防止水体富营养的唯一办法是维持水体氮、磷等主要营养元素收支平衡,治理富营养化的根本办法是从水体中移走过量的氮、磷等主要营养元素。     

铜绿微囊藻在不同供磷水平下对砷胁迫的响应

采用磷饥饿培养后的微囊藻细胞进行不同供磷水平的五价砷(As(V))暴露实验,考察单一胞外磷变化的情况下As(V)对滇池分离出的铜绿微囊藻FACHB905生长及产毒的影响.结果表明胞外磷浓度变化不会影响铜绿微囊藻对As(V)的耐受阈值(-10-7 mol/L).少磷条件下的半数抑制浓度(IC50)为10-2.79 mol/L,比无磷条件下的IC50(10-5.81 mol/L)高3个数量级,并且少磷条件下As(V)与细胞活性位点的结合常数要远低于无磷条件,因此胞外磷在As(V)对微囊藻的毒性效应上具有关键的作用.As(V)对微囊藻单细胞的叶绿素含量没有显著影响,但是对毒素产量具有剂量效应.在少磷条件下,As(V)浓度大于10-7 mol/L可促进微囊藻FACHB905的胞内产毒量;而在无磷条件下,所有As(V)处理组的胞内产毒量均上升78%左右.由上可知,微囊藻在产毒方面与As(V)具有协同效应,这对于全面了解滇池水华暴发期间毒素的变化规律具有一定的参考价值.     

铜绿微囊藻、斜生栅藻对氮磷饥饿的耐受能力研究

在太湖微囊藻水华暴发期间 , 监测了梅梁湾水体中叶绿素 a 和氮磷营养盐的动态变化, 并通过批量培养实验研究了氮磷缺乏对铜绿微囊藻和斜生栅藻生长的影响 , 以探讨两种藻对氮磷饥饿的耐受能力对微囊藻水华形成的影响。结果表明 , 在水华期间 , 水体的氮磷营养盐浓度并不高, 并处于波动状态; 铜绿微囊藻和斜生栅藻对氮磷饥饿的耐受能力存在很大差异 : 在无磷培养基中 , 铜绿微囊藻能保持 8 天的指数生长, 而斜生栅藻在无氮或无磷培养基中生长都非常缓慢。两种藻对磷饥饿的耐受能力均高于氮。通过生长速率的比较, 发现铜绿微囊藻对磷饥饿的耐受能力明显高于斜生栅藻, 因此更能够适应波动的营养供给条件。对营养盐饥饿耐受能力的不同导致两种藻在营养盐波动的情况下微囊藻更易取得优势, 成为水华期间浮游植物的优势种。     

水华束丝藻对磷的生理响应研究

束丝藻(Aphanizomenon Morr. ex Born. et Flah.)是我国淡水水体常见的水华蓝藻之一, 由其引发的水华已产生了严重的环境及生态安全问题。然而, 目前对束丝藻的研究仍相对较少。为了揭示环境因子对束丝藻的影响, 研究从淡水水体限制因子?磷入手, 探讨其对束丝藻的生理生态效应, 研究了不同磷浓度(0.00、0.02、0.05、0.50、1.00 mg/L)对水华束丝藻的生长、光合作用及碱性磷酸酶变化的影响。结果表明: 水华束丝藻在磷浓度低于0.50 mg/L 条件下, 其比生长速率()、最大光合反应(Pm)、饱和光强(Ik)、PSⅡ光化学效率(Fv/Fm)和最大电子传递速率(ETRmax)均下降, 而暗呼吸(Rd)显著增加, 这表明培养基磷浓度低于0.50 mg/L 时,水华束丝藻产生磷营养胁迫, 导致其光合作用受到抑制, 呼吸作用增强, 进而抑制其生长。为了应对这种胁迫, 束丝藻显著增加了其碱性磷酸酶活性(APA), APA 的增加, 使得水华束丝藻能够分解有机形态磷物质转化为其可利用无机磷来缓解磷胁迫。当磷浓度高于0.50 mg/L 时, 水华束丝藻各种参数并没显著性差异, 表明磷浓度高于0.50 mg/L 能够保证水华束丝藻的正常生理特征。这些结果揭示了在低磷条件下, 水华束丝藻能通过调节光合作用和APA 等生理响应, 使其保持生存和竞争优势。       

温度对外源性32P在水、铜绿微囊藻和底泥中迁移的影响

采用同位素示踪法,在实验室模拟研究不同温度下外源性无机磷酸盐在水、铜绿微囊藻(Microcystis aeruginosa)和底泥中的迁移过程.外源性³²P加入水中后,首先是一种与温度无关的快速物理化学分配,大量溶解性磷酸盐迅速进入底泥和微囊藻中.随后水中³²P的迁移主要受微囊藻生长状况的影响.温度升高有利于微囊藻的生长,并提高了微囊藻吸磷的速度.微囊藻中最大外源性磷浓度只与水环境中的初始磷浓度有关.25℃时铜绿微囊藻的生长曲线有7d的对数期,没有明显的稳定期就转入衰亡期.在25℃时,当微囊藻超积累P到一定程度后,其对数生长同细胞内含P量无关.随着时间的推移,外源性³²P不断向底泥中迁移,实验末期所有的³²P都转移到底泥中.提高温度使水中溶解性外源性磷的下降速率加快,7d后水中溶解的外源性磷浓度低于0.00716mg·L^-1.     

1株具有耐镉降解微囊藻毒素细菌的分离鉴定

从安徽镜湖腐烂的蓝藻中筛选出1株细菌,命名为R1,该菌株具有较强的耐镉、溶藻以及可降解微囊藻毒素能力,经16S r DNA序列对比分析鉴定,R1属于气单胞菌属(Aeromonas)。该菌株对Cd~(2+)有很好的耐受性,在含有50 mg/L Cd~(2+)的培养基中仍能正常生长;细菌通过分泌胞外物质溶解铜绿微囊藻,且该胞外物质耐高温,属非核酸或多糖类物质,丙氨酸和苯丙氨酸协同作用而溶藻;在0. 1 mg/L Cd~(2+)存在的情况下,细菌溶藻能力增强;微囊藻毒素的初始浓度为1. 84 mg/L时,7 d时间降解率为40. 2%。     

甲胺磷降解菌的筛选及降解特性研究

从长期受有机磷农药污染的土壤中分离到1株能降解甲胺磷的菌株B15,经生理生化鉴定为巨大芽孢杆菌(Bacillus megaterium)。在甲胺磷无机盐培养基(甲胺磷浓度为0.5%)生长时,最适生长温度为28℃,最适pH为7.0,摇床培养(28℃190 r/min)48 h降解率达到83%。菌株在甲胺磷浓度为1%的无机盐培养基上能生长,但是在甲胺磷浓度为0.5%的无机盐培养基上生长最好,降解率最高。外加碳氮源对菌株的降解率有所提高,但是超过某一浓度降解率随着浓度的增加反而下降。     

斜生栅藻对振荡和磷胁迫的生理生化响应

为了探讨水文条件的变化对常见绿藻水华发生的潜在影响,实验以斜生栅藻为材料,研究了不同水流状态及磷浓度对其生长及磷利用策略的影响。实验分别设置静止条件(0 r/min)、低振荡条件(90 r/min)和高振荡条件(120 r/min),同时设置磷限制(0.2 mg/L)和磷充足(2 mg/L)两组磷浓度,整个实验过程为3周。实验过程测定的指标为:比生长速率、胞外碱性磷酸酶活性、叶绿素a含量以及磷吸收动力学参数。实验结果表明:(1)同静止条件相比,低振荡和高振荡条件均能显著降低斜生栅藻的比生长速率,但是两种不同磷浓度下其比生长速率却无显著性差异。(2)在实验第21天时,振荡条件培养下,斜生栅藻的胞外碱性磷酸酶活性显著高于静止条件培养,与此相反,胞内磷浓度却显著高于静止条件。(3)在磷限制条件下斜生栅藻的叶绿素a含量显著降低,同时两种振荡条件培养均使其在磷充足条件下叶绿素a含量降低。(4)通过磷吸收动力学参数的比较,静止条件培养的斜生栅藻对磷的亲和力高于其在振荡条件下。由此可见,斜生栅藻适应于静止无扰动且磷营养丰富的水体,随着水体中磷浓度进一步升高,静止和水流缓慢的水体存在导致像斜生栅藻这一类绿藻发生水华的风险。       

铜绿微囊藻的分子研究进展

中国淡水湖泊、水库众多,富营养化问题严重。铜绿微囊藻是中国湖泊、水库及其他水域生态系统发生、形成富营养化危害的主要藻类。目前对铜绿微囊藻的研究主要集中在水华成因、生长的特点、作用机理等,对其生命活动相关的分子机制研究不多。该文主要从生物节律、毒素合成、藻胆蛋白合成及其调控机制和ATP合成酶等四个方面综述了铜绿微囊藻的分子研究进展,为今后进一步研究铜绿微囊藻的分子作用机理及其防治具有重要意义。     

微囊藻碳酸酐酶活性在不同环境因素下的调节与适应

测定了3种微囊藻水华中的优势种类,即铜锈微囊藻（Microcystis aetlzginosa Kutz．）,绿色微囊藻（Microcystis viridis（A．Br．）Lemm）,惠氏微囊藻（Microcystis wesenbergii（Kom．）Kom．）,以及微囊藻573（Microcystis sp．573）的碳酸酐酶活性;研究了无机碳、pH、温度、光强、NIP比等环境因素和外源葡萄糖对铜锈微囊藻碳酸酐酶活性的影响,发现微囊藻碳酸酐酶活性受环境中碳酸氢根浓度的调节,故推断碳酸氢根是铜锈微囊藻利用的主要无机碳形式;相比添加葡萄糖进行混合营养培养的细胞,无外源葡萄糖和暗饥饿培养的微囊藻细胞会产生高约6倍的碳酸酐酶活性;光强的改变也会影响碳酸酐酶的活性。     

Genetic variation of the bloom-forming Cyanobacterium Microcystis aeruginosa within and among lakes: implications for harmful algal blooms

To measure genetic variation within and among populations of the bloom-forming cyanobacterium Microcystis aeruginosa, we surveyed a suite of lakes in the southern peninsula of Michigan that vary in productivity (total phosphorus concentrations of approximately 10 to 100 microg liter(-1)). Survival of M. aeruginosa isolates from lakes was relatively low (i.e., mean of 7% and maximum of 30%) and positively related to lake total phosphorus concentration (P = 0.014, r2 = 0.407, n = 14). In another study (D. F. Raikow, O. Sarnelle, A. E. Wilson, and S. K. Hamilton, Limnol. Oceanogr. 49:482-487, 2004), survival rates of M. aeruginosa isolates collected from an oligotrophic lake (total phosphorus of approximately 10 mug liter(-1) and dissolved inorganic nitrogen:total phosphorus ratio of 12.75) differed among five different medium types (G test, P of <0.001), with higher survival (P = 0.003) in low-nutrient media (28 to 37% survival) than in high-nutrient media. Even with the relatively low isolate survivorship that could select against detecting the full range of genetic variation, populations of M. aeruginosa were genetically diverse within and among lakes (by analysis of molecular variance, Phi(sc) = 0.412 [Phi(sc) is an F-statistic derivative which evaluates the correlation of haplotypic diversity within populations relative to the haplotypic diversity among all sampled populations], P = 0.001), with most clones being distantly related to clones collected from lakes directly attached to Lake Michigan (a Laurentian Great Lake) and culture collection strains collected from Canada, Scotland, and South Africa. Ninety-one percent of the 53 genetically unique M. aeruginosa clones contained the microcystin toxin gene (mcyA). Genotypes with the toxin gene were found in all lakes, while four lakes harbored both genotypes possessing and genotypes lacking the toxin gene.     

温度对外源性^32P在水、铜绿微囊藻和底泥中迁移的影响

采用同位素示踪法,在实验室模拟研究不同温度下外源性无机磷酸盐在水、铜绿微囊藻(Micro-fystis aeruginoas)和底泥中的迁移过程,外源性³²P加入水中后,首先是一种与温度无关的快速物理化学分配,大量溶解性磷酸盐迅速进入底泥和微囊藻中,随后水中³²P的迁移主要受微囊藻生长状况的影响,温度升高有利于微囊藻的生长,并提高了微囊藻吸磷的速度,微囊藻中最大外源性磷浓度只与水环境中的初始磷浓度有关,25℃时铜绿微囊藻的生长曲线有7d的对数期,没有明显的稳定期就转入衰亡期,在25℃时,当微囊藻超积累P到一定程度后,其对数生长同细胞内含P量无关,随着时间的推移,外源性³²P不断向底泥中迁移,实验末期所有的³²P都转移到底泥中,提高温度使水中溶解性外源性磷的下降速率加快,7d后水中溶解的外源性磷浓度低于0．00716mg·L^-1。     

Toxic substance from a natural bloom of Microcystis aeruginosa.

A toxic substance contained in the blue-green alga Microcystis aeruginosa was purified and partially characterized. Toxic algal cells were collected from a highly eutrophic lake in Japan, and the toxin was purified by homogenization, ultrafiltration, gel filtration, and ion-exchange chromatography. The final preparation gave a single peak on high-performance liquid chromatography. The toxicity was somewhat less than that reported for other toxins from this alga. The water extract of 6.7 mg (dry weight) of cells and 72 microgram of the purified protein was required to kill a mouse (1 mouse unit). The main amino acids of the toxin were glutamic acid, asparatic acid, alanine, glycine, arginine, and leucine. The molecular weight of the toxin was 2,950 as determined by high-performance liquid chromatography.     

中国淡水微囊藻属常见种类的分类学讨论——以滇池为例

根据中国云南滇池藻类样品的观察结果,对中国分布的淡水微囊藻属Microcystis10个常见种的形态特征进行了描述,同时对它们的分类学进行了讨论,并整理出分类检索表。这10种微囊藻是铜绿微囊藻M.aeruginosa、放射微囊藻M.botrys、坚实微囊藻M.firma、水华微囊藻M.flos-aquae、鱼害微囊藻M.ichthyoblabe、挪氏微囊藻M.novacekii、假丝微囊藻M.pseudofilamentosa、史密斯微囊藻M.smithii、绿色微囊藻M.viridis、惠氏微囊藻M.wesenbergii。最后还讨论了中国报道的其它微囊藻种类的分类学状况。     

Phylogenetic Inference of Colony Isolates Comprising Seasonal Microcystis Blooms in Lake Taihu, China

Blooms of the toxin-producing cyanobacterium, Microcystis spp., are an increasingly prevalent water quality problem and health hazard worldwide. China's third largest lake, Lake Taihu, has been experiencing progressively more severe Microcystis blooms over the past three decades. In 2009 and 2010, individual Microcystis colonies, consisting of four different morphospecies, were isolated and genotyped using a whole-cell multiplex PCR assay. The 16S-23S rDNA-ITS sequences were aligned based on Bayesian inference and indicated that one morphospecies was genetically unique (Microcystis wesenbergii) and three were indistinguishable (Microcystis aeruginosa, Microcystis flos-aquae, and Microcystis ichthyoblabe). Microcystin (mcyB) genes were detected intermittently in two of the morphospecies while the other two morphospecies lacked the mcyB gene in all samples. Water temperature was found to influence bloom formation and morphotype prevalence, and chlorophyll a and temperature were positively and significantly correlated with microcystin concentration. Cooler water temperatures promoted toxigenic strains of Microcystis. Wind appeared to influence the distribution of morphotypes across the lake, with M. aeruginosa and M. ichthyoblabe being more susceptible to wind stress than M. wesenbergii and M. flos-aquae. The results of this study indicated that the blooms were composed of a variety of Microcystis morphospecies, with more genotypes observed than can be attributed to individual morphotypes. We conclude that morphology is not a reliable indicator of toxigenicity in Lake Taihu, and caution should be exercised when the M. aeruginosa morphotype is present because it is capable of producing MC-LR, the most toxic microcystin isoform.     

Modulation and adaptation of carbonic anhydrase activity in Microcystis spp. under different environmental factors

The carbonic anhydrase (CA) activities were determined in three cyanobacterial species, namely Microcystis aeruginosa Kütz., Microcystis viridis (A.Br.) Lemm, and Microcystis wesenbergii (Kom.) Kom, which were dominant in a lake (Dianchi Lake) subject to major blooms. In more detailed experiments on M. aeruginosa, the effects of inorganic carbon, pH, temperature, nitrogen/phosphorus ratio, glucose, and light intensity on CA activity were also investigated. Because of the relatively alkaline pH value of the culture media for the optimum growth of algal cells, bicarbonate ions were the main form of exogenous inorganic carbon. The results showed that the CA activity of M. aeruginosa was influenced dramatically by the concentration of bicarbonate. Consequently, it was suggested that bicarbonate ions were the main form of exogenous inorganic carbon that M. aeruginosa could utilize. Cultures grown in the dark exhibited CA activity six times higher than that of cells cultured mixotrophically with the addition of glucose. Features of eutrophic water bodies promoted an increase in CA activity, and the resulting higher CA activity would accelerate the utilization of inorganic carbon and favor the growth and blooming of Microcystis spp. in eutrophic lakes. Although the experiments were carried out under controlled experimental conditions, they could provide some basic data that would prove useful for the control of cyanobacterial blooms in nature.     

铜绿微囊藻(Microcystis aeruginosa)对惠氏微囊藻(Microcystis wesenbergii)的化感作用

通过混合培养和添加过滤液两种方式观察铜绿微囊藻和惠氏微囊藻的生长曲线,探讨两种微囊藻之间的化感作用。结果表明:在混合培养条件下,两者能够形成相互抑制作用;当两者起始藻密度高于0.5×106cells.mL-1、混合比为1:1时,惠氏微囊藻的生长因化感作用而受到显著抑制(P<0.05),同时惠氏微囊藻也会对铜绿微囊藻产生一定的胁迫作用;处于对数生长期的铜绿微囊藻过滤液能抑制惠氏微囊藻的生长,且惠氏微囊藻起始藻密度低于0.5×106cells.mL-1,连续滴加该过滤液后,其生长受到极显著抑制(P<0.01)。     

Occurrence of mycosporine-like amino acids (MAAs) in the bloom-forming cyanobacterium Microcystis aeruginosa

Here we report the finding of two mycosporine-like amino acids(shinorine and Porphyra-334) in both a culture of the cyanobacteriumMicrocystis aeruginosa isolated from Lake Taihu (China) anda natural phytoplankton sample collected from this lake whichincluded Microcystis spp. Our results are the first to clearlydocument the occurrence of these UV-sunscreen compounds in afreshwater bloom-forming cyanobacterium.