假微型海链藻对不同氮培养条件的响应

Responses of Thalassiosira Pseudonana to different nitrogen conditions

本文选取假微型海链藻为目标微藻,研究其在不同氮源(硝酸盐、亚硝酸盐、铵盐和尿素)和氮饥饿条件下的生长速率和光合作用,以期为阐述海洋微藻对近岸复杂多变的氮环境适应机制提供依据。结果表明,在氮饥饿条件下,假微型海链藻的种群生长受阻,细胞内色素分解,光合作用被显著抑制;在不同氮源条件下,假微型海链藻均能生长但表现出不同的生长模式,但高浓度的铵盐能够对其产生抑制,各条件下藻细胞叶绿素a、叶绿素c和总类胡萝卜素含量在指数生长期无显著差异,而在平台末期,尿素处理组各色素水平显著提高;假微型海链藻光系统Ⅱ的不同光合作用参数在实验末期均表现为铵盐处理组显著高于其他处理组。综上所述,假微型海链藻能够利用不同氮源进行生长,但在不同氮源条件下,种群增长的变化模式与光合作用的响应并不一致,由此推测假微型海链藻在不同氮源条件下光合作用并不是导致其生长模式差异的主要原因。

In this paper, the growth rate and photosynthesis of Thalassiosira pseudonana were studied under different nitrogen sources(nitrate, nitrite, ammonium and urea) and nitrogen starvation, in order to provide a basis for elaborating the adaptation mechanism of marine microalgae to the complex and varied nitrogen environment in the coastal area. The results showed that under the condition of nitrogen starvation, the population growth of T. pseudonana was inhibited, the cellular pigments were decomposed, and the photosynthetic efficiency was significantly inhibited. T. pseudonana grew well in all the four nitrogen sources,but showed inhibition in the high ammonium treatment. There was no significant difference in the contents of chlorophyll a, c and the total carotenoids in the algal cells under different nitrogen source conditions during the exponential growth period, while the levels of pigments in the urea treatment group were significantly increased in the end of the platform phase. Different PSII photosynthetic parameters of T. pseudonana did not vary in different treatments, while the parameters were significantly higher in the 880 μmol/L ammonium treatment than in other treatments at the end of the experiment. In conclusion, T. pseudonana could assimilate different nitrogen source for growth but high concentrations, and the changing patterns of population growth and photosynthesis were not consistent under different nitrogen source conditions, suggesting the different photosynthetic performance of T. pseudonana was not the main reason leading to the difference in the population growth.