不同氮磷营养条件对海黍子生长及抗氧化能力的影响

Effect of nitrogen and phosphorus nutrients on the growth and antioxidation capacity of Sargassum muticum

以经济褐藻海黍子(Sargassum muticum)为研究对象,研究了不同氮、磷营养条件对其生长、生理生化特性以及抗氧化指标的影响。结果表明,海黍子的生长受氮、磷浓度和培养时间的影响显著。氮、磷浓度在不高于400、25μmol·L^(-1)下培养3 d可显著促进海黍子的生长,超过该浓度后,则抑制海黍子的生长;继续培养至7 d时,氮、磷浓度超过100、6.25μmol·L^(-1)均导致海黍子生长速率的下降。海黍子对氮、磷的吸收速率均随着氮、磷浓度的增加呈逐渐升高的趋势,且对NH+4-N和NO-3-N的吸收速率较高,但两者间并无显著差异,而对NO-2-N和PO 3-4-P的吸收速率较低。生理生化指标分析表明,培养3 d时,氮、磷浓度的升高可促进海黍子藻体内叶绿素a和类胡萝卜素的生成,但当继续培养至15 d时,氮、磷浓度高于100、6.25μmol·L^(-1)反而阻止了光合色素的合成。藻体可溶性蛋白的含量在氮、磷加富培养7 d后均显著升高;抗氧化酶如超氧化物歧化酶(superoxide dismutase,SOD)、过氧化氢酶(catalase,CAT)和过氧化物酶(peroxidase,POD)的活性变化不尽相同,在特定的氮、磷浓度和培养时间内显著升高;而当氮、磷浓度升高或超过一定培养时间时,抗氧化酶活性出现不同程度的下降,并逐渐发生过氧化损伤,导致丙二醛(malondialdehyde,MDA)含量显著升高。研究结果可为进一步完善海黍子的健康养殖技术和富营养化污染水域的修复机制研究提供一定的理论参考。

Nitrogen(N)and phosphorus(P)are the main limiting nutrients directly affecting the growth,metabolism,and biochemical properties of macroalgae.This study examined the effects of different N and P nutrients on growth characteristics,physiological and biochemical indexes,antioxidation capacity of economic brown algae Sargassum muticum.Results showed that the growth of S.muticum was significantly affected by N and P concentrations and culturing time,the algal growth was significantly promoted for 3 days after treatments with N and P concentrations within 400,25μmol·L^(-1),while exceeding those concentrations,the algal growth was inhibited.However,after 7 days of culture,when treated with N and P concentrations over 100,6.25μmol·L^(-1),the growth rate of S.muticum decreased.The absorption rates of N and P increased gradually with the increase of N and P concentration,and the absorption rates of NH+4-N and NO-3-N were higher obviously,but there was no significant difference between them,while the absorption rates of NO-2-N and PO 3-4-P were lower relatively.Physiological and biochemical analysis results revealed that within 3 days,the increase of N and P concentration could promote the production of chlorophyll a and carotenoid,but N and P concentrations higher than 100 and 6.25μmol·L^(-1) prevented the synthesis of photosynthetic pigments when cultured for 15 days,suggesting that the photosynthetic performance of S.muticum was changed when treated with extreme N and P conditions over long time.The activities of antioxidative enzymes such as superoxide dismutase(SOD),catalase(CAT)and peroxidase(POD)varied differently,all those elevated obviously first,afterwards decreased in different degrees when N,P concentration or culturing time was beyond a certain range,finally peroxidation damage occurred,resulting in significant accumulation of malondialdehyde(MDA)contents.These findings provide a theoretical reference for healthy culture technique of S.muticum and improve our understanding of the development and utilization of marine algae on bioremediation of eutrophic water.