南极冰藻Pyramidomonas sp.和Chlorophyceae L-4的优化培养

Optimum culture of antarctic ice microalgae Pyramidomonas sp. and Chlorophyceae L-4

设计温度、光强、盐度、pH值、营养盐等培养条件,测定其对南极冰藻中2种绿藻Pyramidomanassp.和Chloro phyceaeL-4生长的影响。研究结果表明,f/2培养基为适合这2种南极绿藻生长的适宜培养基。Pyramidomonassp.最适生长温度为2～6℃,pH为9.0;ChlorophyceaeL-4的最适生长温度为-3～6℃,pH为8.0～8.5。2种南极绿藻生长最适光强为7.0～60.0μE·m-2·s-1,最适盐度为22～33。选择NaNO3为培养基中的氮源,适合Pyramidomonassp.的浓度为0.88mmol·L-1。氮源浓度在0.56～1.47mmol·L-1,对ChlorophyceaeL-4生长影响不明显。适宜2种南极绿藻生长的磷酸盐浓度为0.13mmol·L-1。

Antarctic is an extreme cold area with high salinity and strong UV irradiation. Antarctic ice microalga, the main producer of primary production, play a very important role in marine ecology system. Ice microalga develop many mechanisms to adapt these extreme environments after a long time evolution. In order to use completely the value of ice microalga, the effects of culture conditions (medium, temperature, irradiance, salinity, pH and nutrient sources) on two species of antarctic green microalga were investigated. Pyramidomonas sp. and Chlorophyceae L-4 were cultured in f/2 medium. The OD_(440), chlorophyll content and specific growth rate were determined every two days. The results showed that f/2 medium was the favorable one for Pyramidomonas sp. and Chlorophyceae L-4 among f/2, Provasoli and green algae medium. These two species of alga were developed under 4 different temperature of -3, 2, 6 and 10 ℃, the range of optimum temperature for the growth of Pyramdoimonas sp. and Chlorophyceae L-4 is 2-6 ℃ and -3-6 ℃ respectively. After the irradiance of 0.6, 3.0, 7.0, 20.0 and 60.0 μE·m^(-2)·s^(-1), the maximal growth quantity of Pyramidomonas sp. and Chlorophyceae L-4 were both got under 7.0-60.0 μE·m^(-2)·s^(-1). The salinity of f/2 medium were adjusted to 11, 22, 33, 66, 100 and 150 by adding crude salt and sterile water, and the results showed 22-33 was optimum. The pH value of f/2 medium to 6.0, 7.0, 8.0, 9.0 and 10.0 with 0.1 mol·L^(-1) HCl and NaOH were regulated, the optimum pH value for the growth of Pyramidomonas sp. was 9.0, while Chlorophyceae L-4 was 8.0-8.5. In all nitrogen sources (NaNO_3, NH_4Cl and urea), NaNO_3 was optimum for the two species of alga. Pyramidomonas sp. and Chlorophyceae L-4 were cultured in different NaNO_3 level of 0, 0.56, 0.88, 1.18 and 1.47 mol·L^(-1), and our experiments showed that the optimum concentration for Pyramidomonas sp. is 0.88 mmol·L^(-1), and 0.56-1.47 mmol·L^(-1) has no obvious effect on Chlorophyceae L-4. These two species of green microalga were cultured in f/2 medium consisting of KH_2PO_4 (phosphate source) of 0.015, 0.033, 0.065 and 0.13 mol·L^(-1), and the optimum KH_2PO_4 concentration for their growth was both 0.13 mmol·L^(-1). Antarctic ice microalga under the extreme environment have many important substances, such as antioxidant, antifungal, antitumour, etc.. The optimum culture conditions were founded after our experiments, which can provide basic evidences for ice microalga exploitation and large-scale culture.