环境因子对东海原甲藻生长及脲酶活性的影响

Abstract

PDF HTML阅读 XML下载 导出引用 引用提醒 环境因子对东海原甲藻生长及脲酶活性的影响 DOI: 10.5846/stxb201408251681 作者: 作者单位: 暨南大学水生生物研究中心,暨南大学水生生物研究中心,暨南大学水生生物研究中心,暨南大学水生生物研究中心,暨南大学水生生物研究中心,暨南大学水生生物研究中心 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目(U1133003, 40776078) Effects of environmental factors on the growth and urease activity of the harmful dinoflagellate Prorocentrum donghaiense Author: Affiliation: Key Laboratory of Water Eutrophication and Red-tide Control,Department of Education of Gangdong Province Research centre of Hydrobiology,Jinan University,Key Laboratory of Water Eutrophication and Red-tide Control,Department of Education of Gangdong Province Research centre of Hydrobiology,Jinan University,Key Laboratory of Water Eutrophication and Red-tide Control,Department of Education of Gangdong Province Research centre of Hydrobiology,Jinan University,Key Laboratory of Water Eutrophication and Red-tide Control,Department of Education of Gangdong Province Research centre of Hydrobiology,Jinan University,Key Laboratory of Water Eutrophication and Red-tide Control,Department of Education of Gangdong Province Research centre of Hydrobiology,Jinan University,Key Laboratory of Water Eutrophication and Red-tide Control,Department of Education of Gangdong Province Research centre of Hydrobiology,Jinan University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以我国东南沿海大规模赤潮原因种东海原甲藻为实验材料,研究了环境因子对其生长及脲酶活性的调控作用。结果表明,东海原甲藻的适宜生长温度为20-25℃,而25℃下脲酶活性最高。在光强2 μmol m-2 s-1 条件下细胞密度显著下降(P < 0.05),但仍能维持较高的脲酶活性(9.405 fmol h-1 个-1)。在盐度20-40范围内,东海原甲藻能够维持快速生长和较高的脲酶活性。氮源组成对东海原甲藻生长无显著影响,但对脲酶活性影响较大。具体而言,东海原甲藻脲酶活性与尿素浓度呈显著正相关关系,而无机氮源NH4+和NO3-对其脲酶活性具有显著的抑制作用,在氮缺乏条件下脲酶活性明显增强。东海原甲藻脲酶活性对环境温度、光照、盐度和营养的响应特征可能是在长期进化中形成的生态适应策略,使其在无机氮源不足时得以转而利用有机氮源,从而在资源竞争中占据有利地位。 Abstract:In the last few decades, the geographic distribution and frequency of harmful algal blooms (HABs) have been increasing worldwide, and have resulted in severe economic losses and ecological disaster. There has been a scientific consensus that there is a positive relationship between occurrences of HABs and increased eutrophication due to human activities in coastal waters. Studies demonstrated that urea has seen wide use in agriculture as a major nitrogen fertilizer in recent years, and consequently, concentrations of urea in aquatic environments have increased dramatically, becoming an important component of dissolved organic nitrogen (DON) in coastal waters. Other studies demonstrated the presence of a positive correlation between the increased input of urea into coastal waters and HABs frequencies. However, the ecological role of urea in triggering HABs, and the mechanism by which it does so (in a species-specific and physiological context in particular), are still unclear. The armored dinoflagellate Prorocentrum donghaiense is a representative HABs-causing alga found in the southeastern coastal waters of China, and has caused serious damage to fisheries and aquaculture facilities, and threatened coastal aquatic ecosystems. This species has shown a wide range of tolerance to light, temperature, and salinity, and is capable of utilizing both inorganic (NO3- and NH4+) and organic (e.g. urea and amino acids) forms of nitrogen (N). Based on our prior study, in which we demonstrated that P. donghaiense exhibits a higher growth rate when grown in media containing urea as the sole N source, compared to those grown with NO3- as the N source, we investigated the effects of environmental factors (temperature, light intensity, and salinity) on the growth of P. donghaiense, and further explored the potential regulating effects of these factors and different forms of N on the activity of urease, a key enzyme involved in the metabolism of urea. The optimal temperatures for P. donghaiense growth were between 20 and 25℃, while the highest urease activity was observed at 25℃. Light was observed to significantly influence urease activity: high urease activity (9.405 fmol h-1 cell-1) was observed even at lower irradiance levels (< 2 μmol m-2 s-1), where the cell density was the lowest. Compared to light and temperature, salinity had the smallest impact on growth and urease activity, i.e., both relatively high growth rates and urease activity were measured at salinities ranging from 20 to 40 psu. Regarding the different effects of different nitrogen resources, P. donghaiense was capable of using all forms of nitrogen provided: NO3-, NH4+, and urea, to meet its growth requirement. However, urease activity, was significantly inhibited by NH4+ and NO3-, but enhanced by the presence of elevated concentrations of urea. More specifically, P. donghaiense exhibited the strongest urease activity three days after inoculation in the urea treatment group, while, in contrast, urease activity in media with NH4+ or NO3- as the sole N source did not change significantly over time and was significantly lower than that observed in the urea-augmented medium. Moreover, we found that NH4+ had a stronger inhibitory effect on the urease activity of P. donghaiense than NO3-. In the N source conversion experiments, urease activity in the NH4+ substrate was still lower than that in NO3- substrate after the addition of equal amount of urea. In addition, urease activity was significantly elevated when ambient nitrogen was deficient. The response of P. donghaiense urease activity and growth rates to the temperature, light, salinity, and nutrient differences observed in this study may reflect an ecological adaptation of P. donghaiense, which allows it to make use of organic nitrogen when inorganic nitrogen sources are insufficient, providing P. donghaiense with a competitive advantage over co-occurring phytoplankton species when the availability of urea is higher than inorganic forms of nitrogen. 参考文献 相似文献 引证文献