温度对雨生红球藻生长、虾青素累积和抗氧化能力的影响

Effects of Temperature on Growth,Astaxanthin Accumulation and Antioxidative Capacity in Haematococcus pluvialis

雨生红球藻(Haematococcus pluvialis)是天然虾青素含量最高的生物。为探讨雨生红球藻生长和虾青素累积的最适温度条件以及温度胁迫下藻细胞内各抗氧化机制之间的关系,采用显微计数和生化分析方法,研究了不同培养温度对其藻细胞密度、生长速率、虾青素含量、超氧化物歧化酶(SOD)活性、谷胱甘肽过氧化物酶(GSH-Px)活性和总抗氧化能力(T-AOC)的影响。结果表明,雨生红球藻细胞密度、生长速率和虾青素含量随温度的增加先升高、后下降,SOD和GSH-Px活性随着温度的增加而逐渐上升,而T-AOC则随温度的增加先升高、后下降、再升高;藻细胞密度、生长速率、虾青素含量、SOD活性、GSH-Px活性和T-AOC均在培养温度为10℃时呈现出最低值;藻细胞密度、生长速率、虾青素含量和T-AOC在培养温度为25℃时达到最大值,而SOD和GSH-Px活性在培养温度为35℃时最高;在25℃时,藻细胞密度在培养至第9天达到13.90×104个/m L,前9天的生长速率达到0.17/d,藻细胞虾青素含量和T-AOC在培养的第18天分别达到3.07 mg/g和2.07 U/mg;在35℃时,藻细胞SOD活性和GSH-Px活性在培养的第18天分别达到2.12 U/mg和2.43 U/mg;藻细胞内虾青素和抗氧化酶活性互为补充,共同保护藻细胞免受环境胁迫条件下的氧化损伤。研究结果可为雨生红球藻大规模培养和虾青素规模化生产与应用提供理论基础。

Haematococcus pluvialis is recognized as the best source of natural astaxanthin. Research has shown that accumulation of astaxanthin in H. pluvialis cells is a defense response to unfavorable growth conditions,such as nitrogen deficiency,intensive illumination,high salinity and temperature,and H. pluvialis can synthesise and accumulate astaxanthin in concentrations up to 6% of its ash free dry weight. The influence of temperature on the growth of H. pluvialis and the accumulation of astaxanthin has been reported,but investigators have reached different conclusions. Based on these studies,we have further investigated the effect of temperature on cell density,growth rate,astaxanthin content,superoxide dismutase（ SOD）,glutathione peroxidase（ GSH-Px） activities and total antioxidant capacity（ T-AOC） of H. pluvialis. Using microscopic counting and biochemical analysis,the optimum temperature for H. pluvialis growth and astaxanthin accumulation was determined and the antioxidant mechanism in H. pluvialis cells was clarified. Haematococcus pluvialis obtained from the freshwater algae culture collection at the Institute of Hydrobiology（ FACHB-collection） were cultivated in a basal medium in glass flasks in a chamber with light and temperature control. H. pluvialis cultures were separated into six groups and cultured at temperatures of10℃,15℃,20℃,25℃,30℃ and 35℃. Triplicate cultures of each group were maintained at a light intensity of100 μmol / m2·s,a photoperiod of 12 h light/12 h dark and a culture period of 18 d. The concentration of H. pluvialis cells for each group was determined every three days,the content of astaxanthin every six days,the growth rate on day 9 and the activities of SOD,GSH-Px and T-AOC were determined on day 18. Cell density,growth rate and astaxanthin content increased initially and then decreased with increasing temperature. SOD and GSH-Px activities increased with temperature,while T-AOC increased initially,declined and finally increased again with rising temperature. Cell density,growth rate,astaxanthin content and activities of SOD and GSH-Px,and T-AOC showed the lowest values when the algae was cultured at 10℃. Cell density,growth rate,astaxanthin content and T-AOC reached maximum values at 25℃,whereas the highest SOD and GSH-Px activities were obtained at 35℃. The cell density reached 13. 90 × 10^4 cells / mL on day 9 at 25℃,with a growth rate of 0. 17 / d for the first 9 days,and the astaxanthin content and T-AOC reached 3. 07 mg / g dry weight and 2. 07 U / mg on day 18 of the culture. At 35℃,SOD and GSH-Px activities reached 2. 12 and 2. 43 U / mg on day 18 of the culture,respectively. The antioxidant activities of astaxanthin and antioxidant enzymes in algal cells complement one other to protect algae cells from oxidative damage under environmental stress. The results of this study will provide a theoretical foundation for mass culturing H. pluvialis and the large-scale production of astaxanthin.