二氧化锗对共培养萱藻丝状体和硅藻生长的影响

Effects of germanium dioxide on the growth of filaments of Scytosiphon lomentaria and diatoms in co-cultured conditions

为抑制萱藻丝状体保存和扩增过程中出现的小伪菱形藻与碎片菱形藻的生长,本实验应用实验生态学方法,分别建立了丝状体与小伪菱形藻、丝状体与碎片菱形藻、丝状体与小伪菱形藻和碎片菱形藻的共培养体系,研究了1.00～4.00μg/mL二氧化锗(GeO_2)对共培养条件下丝状体生长发育及附生硅藻生长的影响。结果显示:(1)处理萱藻丝状体和硅藻共培养体系的适宜GeO_2浓度为1.00～2.50μg/mL,各实验组14 d的硅藻抑制率均高于67.33%±5.18%,且丝状体生长发育良好,2.00μg/mL为最适浓度,此浓度下丝状体日均增长率最高,在各培养体系中均大于11.00%,且诱导后孢子囊枝比例和孢子囊直径分别为57.47%±5.31%和(24.55±1.01)μm,与对照组差异不显著;(2) 3.50和4.00μg/mL GeO_2虽对硅藻抑制效果更佳,但同时也会抑制丝状体生长和后期孢子囊的形成与发育,其中4.00μg/mL GeO_2可导致丝状体死亡;(3)碎片菱形藻较小伪菱形藻对GeO_2更敏感。实验14 d,各浓度GeO_2对碎片菱形藻的抑制率为(82.10%±2.40%)～(96.35%±0.79%),均高于同浓度GeO_2对小伪菱形藻的抑制率;同时在丝状体与小伪菱形藻和碎片菱形藻的共培养体系中,碎片菱形藻占硅藻比例随GeO_2浓度升高而相应下降。

In order to suppress the growth of Pseudo-Nitzschia sicula and N. frustulum appearing during the cultivation of filaments of Scytosiphon lomentaria in our lab, the effects of germanium dioxide(GeO2) at1.00-4.00 μg/mL on the growth and development of filaments of S. lomentaria and the growth of epiphytic diatoms were studied in 3 different kinds of co-cultured systems. Results indicated that: the suitable concentrations of GeO2 for co-cultured systems of filaments and diatoms were 1.00-2.50 μg/mL, at which the percentage decreases of diatoms were all above 67.33%±5.18% after 14-day co-culturing, meanwhile the filaments of S.lomentaria were in good conditions and good developments. 2.00 μg/mL was the most suitable concentration of GeO2 since the filaments of S. lomentaria, under that condition, had the highest daily average growth rates which were all higher than 11.00% in 3 kinds of co-cultured systems, and ratios of sporangial branchlets as well as average diameter of sporangia were 57.47%±5.31% and(24.55±1.01) μm, respectively, which were not significantly different from those in control groups. Although diatoms were suppressed more effectively when the concentrations of GeO2 was up to 3.50 and 4.00 μg/mL, the growth of filaments, the ratios of sporangial branchlets and average diameter of sporangia after inducing were also influenced negatively. What is more, filaments were dead when the concentration of GeO2 reached 4.00 μg/mL. N. frustulum is more sensitive to GeO2 than P. sicula.After 14-day co-culturing, the percentage decreases of N. frustulum were between(82.10%±2.40%)-(96.35%±0.79%)at any concentration of GeO2, which were higher than the percentage decreases of P. sicula under same conditions.Moreover, on the 14th day in co-cultured systems of filaments of S. lomentaria, P. sicula and N. frustulum, there was negative correlation between percentages of N. frustulum in the two species of diatoms and concentrations of GeO2.