【作者】 石岩峻；

【导师】 马润宇； 丛威；

【作者基本信息】 北京化工大学 ， 生物化工， 2004， 博士

【摘要】 本文主要考察了三种常见的赤潮藻,一种硅藻中肋骨条藻,两种甲藻微小原甲藻和塔玛亚历山大藻,对营养盐的吸收及生长和相关的特性。塔玛亚历山大藻在低氮条件下具有高比生长速率,在高磷下细胞密度较大。维持培养液中适当低的氮水平,并保证足够量的磷供应即较低的氮磷比是促进塔玛亚历山大藻生长的重要原因。在藻细胞对数生长中期只补加适量氮源或在对数生长末期补加氮源和磷源,藻细胞稳定期生物量可以提高到对照组的8-9倍,相应得到的细胞的毒素产率也增加8倍之多。而在藻细胞对数生长中期补加氮源和磷源或在藻细胞对数生长末期只补加氮源,稳定期生物量的增加不到一倍。塔玛亚历山大藻细胞以单位叶绿素a表示的光合作用光饱和速率(Pmchl a)、光合效率((chl a)及暗呼吸速率(Rdchl a),在高氮下最低。随着培养液中磷浓度的增加,以单位叶绿素a表示的光合作用光饱和速率及光合效率有增加的趋势。微小原甲藻细胞在高营养源(高氮或高磷)状态下生长具有较高的单位叶绿素a表示的光饱和的光合作用速率(Pmchl a)和光饱和点(Ik),而低营养盐条件下中肋骨条藻以单位叶绿素a表示的光饱和的光合作用速率(Pmchl a)和光合效率((chl a)与高氮或高磷条件下生长的中肋骨条藻细胞相当。中肋骨条藻、微小原甲藻和塔玛亚历山大藻三种赤潮藻对营养盐氮、磷的吸收动力学参数半饱和常数Ks分别为0.40、5.18、30.9?M 和0.65、1.66、2.70?M;对营养盐氮、磷的生长动力学参数半饱和常数分别为7.61、20.52、35.55?M和0.21、1.39、1.52?M,中肋骨条藻值最小,塔玛亚历山大藻值最大,而比生长速率相反。属于甲藻的微小原甲藻和塔玛亚历山大藻与属于硅藻的中肋骨条藻相比,具有较低的营养盐亲合力和比生长速率。中肋骨条藻在富含硅的培养液中易成为优势藻,而塔玛亚历山大<WP=4>藻和微小原甲藻的生长会受到明显抑制。在低硅培养液中,如SiO32-为10?M,两种甲藻能够以一定速率生长。其中,在氮限制条件下,细胞个体小、对氮需求较少的中肋骨条藻快速增殖,而个体大且对氮需求较大的两种甲藻由于氮源的限制生长期明显缩短,与单种培养相比,它们的最大细胞密度很低;在磷限制条件下,中肋骨条藻细胞增殖受到明显抑制,生物量偏低,而两种甲藻受到的影响则较小,生长速率与最大细胞密度与氮限制下相当。低硅高磷条件下,中肋骨条藻稳定期缩短,细胞数很快下降,而微小原甲藻却以一定的速率持续生长,细胞数不断增加,最终取代中肋骨条藻成为优势种。低锌主要是通过影响藻细胞的碳酸酐酶的活性来限制细胞对无机碳的利用和CO2的固定,进而限制微藻的光合作用和生长。不同种类赤潮藻对锌限制响应的范围和程度有差异,中肋骨条藻对锌限制不如微小原甲藻敏感,而高锌产生的毒害对中肋骨条藻的影响更为显著。微量金属元素对赤潮藻类影响的不同可能改变水体中赤潮藻类的优势种群。在开放式大洋中,处在锌限制条件下的硅藻更易取得优势地位,而在污染严重的水体中,金属元素的过量,使得对高锌毒害较不敏感的甲藻类更易形成水华。中肋骨条藻能够以有机磷为唯一磷源生长繁殖,且其比生长速率、最大细胞密度以及碳酸酐酶和碱性磷酸酶的活性受培养基中Zn2+浓度的影响。藻细胞通过胞外碱性磷酸酶对有机磷源吸收利用。藻细胞光合作用对无机碳的亲合力受胞外碳酸酐酶控制,亲合力对Zn2+浓度的变化较为敏感。溶解性有机磷的利用增加了藻细胞对Zn2+的消耗。更多还原

【Abstract】 The nutrient availability, growth and other related characteristics of three red tide algae, Skeletonema costatum, a diatom, Prorocentrum minimum and Alexandrium tamarense, two dinoflagellates, were investi- gated. Alexandrium tamarense showed the highest specific growth rate at low nitrate level. Maintenance of continues low level nitrate with sufficient supply of phosphate, namely low N:P ratio, may facilitate the growth of Alexandrium tamarense. When cultures at low level nitrate were supplemented with nitrate in middle exponential growth phase or with nitrate and phosphate in stationary growth phase, the cell yield was markedly enhanced, it was 8-9 times of the control culture without any nitrate and phosphate supplement,the toxin yield was also increased by over 8 times. However, supplementation with nitrate and phosphate in middle exponential growth phase or with nitrate in stationary growth phase increased the cell yield by no more than 2 times. The cells of Alexandrium tamarense grown under high level nitrate showed the lowest values of chlorophyll a-specific light-saturated photosynthetic rate (Pmchl a), dark respiration rate (Rdchl a) and apparent photosynthetic efficiency ((chl a). The values of Pmchl a, and (chl a showed increasing trend with the increase of phosphate concentration in culuture medium. For the cells of Prorocentrum minimum, the higher chlorophyll a-specific light-saturated photosynthetic rate(Pmchl a)and higher light-saturated point (Ik) at which photosynthesis is initially were observed when the nutrient levels were high. For the cells of <WP=6>Skeletonema costatum, the cells grown at low nutrient levels were active and their chlorophyll a-specific light-saturated photosynthetic rate (Pmchl a) and apparent photosynthetic efficiency ((chl a) changed not markedly with the change of nutrient levels.The half-saturation constants Ks for the uptake of nitrate and phosphate by Skeletonema costatum, Prorocentrum minimum and Alexandrium tamarense were 0.40, 5.18, 30.9?M and 0.65, 1.66, 2.70?M respectively. For growth dynamics the values Ks associated with nitrate and phosphate were 7.61, 20.52, 35.55?M and 0.21, 1.39, 1.52?M respectively. Skeletonema costatum gave the lowest Ks value but Alexandrium tamarense showed the highest one, while the specific growth rate exhibited contrary results. Nutrient uptake affinity and specific growth rates of both Alexandrium tamarense and Prorocentrum minimum were lower than those of diatom Skeletonema costatum. In Silicate-rich cultures Skeletonema costatum was a good competitor, and the other two dinoflagellates were growth-restricted. This result was not due to N or P limitation. In the medium with 10?M SiO32- the two dinoflagellate could grow at a certain growth rate. Under nitrate-limited conditions the growth of Skeletonema costatum increased significantly due to its small cell size and lower demand for nitrogen, while the two dinoflagellate with large cell size increased slowly and resulted very low cell yields. Under phosphate-limited conditions, the propagation of Skeletonema costatum was severely restricted and the cell density apparently decreased. The restriction on dinofalgellates caused by phosphate limitation was not severely. In the medium with low silicate and high level phosphate, the growth of Skeletonema costatum decreased at later growth stage, while the cell numbers of Prorocentrum minimum increased continuously and finally it became dominant specie.The general effects of zinc limitation on algae are the reduction in carbonic anhydrase activity then carbonic anhydrase activity further influenced the uptake of inorganic carbon and affected the CO2 fixation <WP=7>which in turn resulted in the decrease of photosynthetic efficiency. The response to zinc limitation were different from various species. The results obtained in this study showed that Prorocentrum minimum was more sensitive to zinc limitation than Skeletonema costatum, however excessive zinc imposed much more restriction on the growth of Skeletonema costatum than tho更多还原