微藻营养盐限制的检测方法

Methods for determining microalgal nutrient limitation

对检测微藻营养盐限制的几种主要方法进行综述和比较,结果认为:1)细胞内各营养盐的比值法虽然比较简便,但所得值不稳定,容易受光照、CO2浓度、营养盐状况等因子影响;2)营养盐强化法是检测微藻营养盐限制最常用的一种方法,但易受微藻种类组成的影响,而且添加一种营养盐后可能导致其他营养盐的缺乏;3)营养盐吸收动力学法可应用于N、P限制的快速检测,但微藻对营养盐的吸收速率因微藻的种类、营养盐的初始浓度和营养盐状况的不同而异;4)生化法曾被广泛地用于N、P、Fe等营养盐限制的研究,但测量过程较复杂,需要时间较长,且不同种间存在差异;5)傅立叶变换红外光谱法可通过限制性营养盐添加前后微藻细胞红外光谱的变化来检测营养盐状况,能快速准确地反映检测结果,但仪器占地面积较大,且价格昂贵;6)叶绿素荧光技术具有快速、灵敏、对细胞无损伤、需要样品量少的优点,是检测微藻营养盐限制最有发展前景的方法。

The merits and methodological limitations of several main approaches for determining microalgal nutrient limitation are briefly reviewed and compared. 1 ） The elemental ratios of microalgae can reflect the status of nutrient limitation, but the result is far from constant and easily influenced by light, CO2 availability and nutrient status. 2） Enrichment experiments have been commonly used to determine the nutrient limitation in phytoplankton and natural water, but it can be influenced by the species composition of the seeding /inocula phytoplankton sample and addition of one macronutrient may induce limitation of other nutrients. 3） Nutrient uptake kinetics can be used for detecting microalgal nutrient limitation, as nutrient limited cells exhibit increased uptake capacity or efficiency for the specific nutrient after it is re-supplied. But the uptake rates vary with a range of factors including microalgal species, nutrient history and nutrient status. 4） Biochemical approach has been used extensively in the study of N,P and Fe deprivation, but this method entails destruction of the sample and time consuming, and complicated process. 5） Fourier-transform infrared microspectroscopic analysis can reveal dramatic spectral differences between nutrient-limited and nutrient-replete microalgal cells and represents a novel method to investigate macromolecular synthesis in response to changes in nutrient supply. But this method has the limitation of requiring bulky and expensive equipment. 6） The chlorophyll fluorescence measurements are non-destructive and highly sensitive, thus require only small volumes and low concentration of experimental samples. These characteristics make it become an increasing potential approach for exploring nutrient status of microalgae and their physiological response to varying environmental conditions.