南极冰藻绿藻B-7的异养培养

Heterotrophic cultivation research of Antarctic ice algae Chlorophyceae B-7

2001年10月至2002年4月在中国第18次南极科学考察时采得南极海水水样和海冰样品,从中分离纯化出南极冰藻绿藻B 7,通过单因子试验及L25(56)正交试验表对其进行异养培养条件研究,并采用全量凯氏定氮法及气相色谱法测定该藻在异养培养条件下生化组成的变化。结果表明,在异养培养条件下,绿藻B 7的生长速率约为自养条件下的2倍。绿藻B 7异养培养最适有机碳、氮源分别为葡萄糖、蛋白胨;绿藻B 7的最佳异养培养条件为:培养温度4℃,培养液起始pH值6～8,250mL三角瓶装液量50mL,接种量20%。与自养条件相比,异养绿藻B 7细胞内生化组成有所变化:蛋白质含量升高,饱和脂肪酸及多不饱和脂肪酸占总脂肪酸的含量下降,单不饱和脂肪酸含量基本维持不变或有所上升。研究说明,通过异养培养可有效地提高绿藻B 7的藻体最终收获量,且异养条件下绿藻B 7的营养价值不低于自养绿藻B 7。在我国北方寒冷季节,可以利用异养培养方式大规模培养南极绿藻B 7,为育苗提供充足的饵料。

The Antarctic water samples and sea ice samples from which Antarctic ice algae Chlorophyceae B-7 used in this research were collected during the 18th China Antarctic science review from October 2001 to April 2002. The studies on the heterotrophic culture condition of Chlorophyceae B-7 were carried out using the monofactorial experiment and L_(25)(5~6) orthogonal design. The change of biochemical composition of Chlorophyceae B-7 under heterotrophic culture was determined by using Kjeldahl determination method and gas chromatograph method. The results showed that the growth rate of Chlorophyceae B-7 under heterotrophic culture (0.009 8 h^(-1)) was about twice as that of Chlorophyceae B-7 under phototrophic culture. The optimal organic carbon and nitrogen source of Chlorophyceae B-7 under heterotrophic culture were glucose and peptone, respectively. The optimal heterotrophic culture condition of Chlorophyceae B-7 was: 4 ℃ cultivation temperature, initial pH value 6-8, 50 mL medium in 250 mL flask and seeding ratio 20%(V/V). Under this condition, Chlorophyceae B-7 got the highest biomass. The biochemical composition of Chlorophyceae B-7 got changes under heterotrophic culture. Compared with phototrophic, the protein content and monounsacturated fatty acid content increased, whereas the sacturated and polyunsacturated fatty acid contents decreased. The protein content under heterotrophic culture reached about 50% of the algae dry weight, about twice as that of Chlorophyceae B-7 under phototrophic culture. Under heterotrophic culture, the biomass of Chlorophyceae B-7 could be improved effectively and the nutrition value was no less than that under phototrophic culture. It is suggested that during cold winter in the north of China, Chlorophyceae B-7 could be cultured extensively through heterotrophic culture and can be used as mariculture food in the process of breeding.