重金属镉对铜藻生长及其生物活性成分积累的影响

为研究水体重金属污染对经济海藻的生长和品质造成的严重影响,以经济褐藻铜藻Sargassum horneri为研究对象,在温度为15℃的条件下,研究了由Cd Cl2·2.5H2O配制不同浓度(0、0.1、0.5、1.0、5.0 mg/L)的重金属镉胁迫对铜藻生长、光合色素、可溶性糖、可溶性蛋白等生理生化指标,以及对生物活性成分(岩藻黄素、褐藻胶和褐藻多酚)积累的影响。结果表明:对照组藻体的特定生长率(SGR)在15 d内持续升高,0.1、0.5 mg/L Cd处理组的SGR在试验前10 d内逐渐升高,然后保持稳定至第15天,1.0 mg/L处理组的SGR随着培养时间的延长呈波动变化状态,而5.0 mg/L处理组的SGR呈先升高后降低的趋势;藻体的各项生理生化指标随胁迫时间呈不同的变化趋势,但在试验第15天时,各胁迫组藻体的叶绿素a、类胡萝卜素和可溶性蛋白含量均显著低于对照组(P0.05),而可溶性糖含量则显著高于对照组(P0.05);铜藻的岩藻黄素和褐藻多酚含量在不同浓度的Cd胁迫下均有极大程度的下降,且Cd胁迫浓度越高,降幅越大,而褐藻胶含量在Cd浓度≤0.5 mg/L胁迫下未有显著变化(P0.05),在Cd≥1.0mg/L时显著下降(P0.05)。研究表明,在铜藻产业化开发应用过程中,其养殖海域的重金属污染是需要考虑的重要因素。

Effect of cadmium stress on growth and accumulation of bioactive compounds in brown alga Sargassum horneri

The effects of cadmium concentrations on growth, physiological biochemical characteristics including photosynthetic pigment, soluble sugar and soluble protein) and bioactive accumulation of fucoxanthin, alginate and phlorotannins were studied in brown alga Sargassum horneri exposed to cadmium concentrations of 0, 0.1, 0.5, 1.0 and 5.0 mg/L prepared by CdCl2?2.5 H2 O at water temperature of 15 ℃ for 15 days to evaluate effects of heavy metal polution on growth and quality of economically important sea weed. The results showed that the brown alga in control group had continual increase in specific growth rate (SGR) in thalli. The brown alga exposed to 0.1 and 0.5 mg/L Cd, however, showed gradual increase in SGR during the first 10 days and then stable to 15th day, the brown alga exposed to 1.0 mg/L Cd showing a fluctuation trend in SGR with time, and exposed to 5.0 mg/L having elevated SGR first and then being decreased. The physiological biochemical indices of the macroalgae were found to be varied with exposed period, on the 15th day, significantly lower contents of chlorophyll a, carotenoid and soluble protein than those in the control group(P<0.05), and significantly higher soluble sugar content than that in the control group ( P<0.05) . The contents of fucoxanthin and phlorotannins were found to be decreased significantly in the brown alga under Cd stress, with the greater decline range at higher concentration of Cd. There was no signifi-cant change in alginate content under Cd concentration of ≤0.5 mg/L( P>0.05) , significant decrease at Cd con-centration of≥1.0 mg/L( P<0.05) . The findings suggest that the heavy metal pollution be considered as an impor-tant factor in development of the brown alga industry in mariculture area.