一种能源微藻IOAC689S的筛选和优化培养

A biodiesel producing micro-algal strain IOAC689S and optimization of its culture parameters

利用氯仿-甲醇（2：1）提取和气相色谱技术,对采集自渤海、黄海、东海、南海海域以及实验室现有的海洋微藻进行了总脂和脂肪酸检测,从中筛选到一株高产油微藻IOAC689S,其油脂含量在快速生长阶段达到37.5%,其中可作为生物柴油开发的18C以下脂肪酸占总脂肪酸的91.03%。通过对其ITS和5.8S rDNA全序列进行扩增,得到了包括18S rDNA及28S rDNA部分序列在内的全长为998bp的DNA片段,初步确定为一种绿藻。随后利用氧电极检测藻液净光合放氧速率的方法,研究了光照强度、温度、盐度、pH值、碳源、N和P浓度等不同理化因子对IOAC689S光合作用的影响,从而得到该藻优化后的培养参数如下：光照强度200μmol/（m2.s）、光下培养温度30~35℃,黑暗培养温度24℃、盐度30、pH值7~9、NaNO3氮源质量浓度75 mg/L、NaH2PO4磷源质量浓度40 mg/L,而NaHCO3碳源对该藻生长没有明显作用。利用上述优化条件培养该藻获得了较好生长效果,平均比生长速率为0.210 d？1,每周生物量可增加3.8倍。实验结果还表明在培养后期当pH值提高至10~11时,藻体易发生沉降,可以利用该特性进行藻体收获。

Total lipid contents and fatty acid compositions of marine microalgae collected from Bohai,Huanghai,Donghai,and Nanhai area and the ones that already existed in the lab of Institute of Oceanology,Chinese Academy of Sciences were analyzed by chloroform-methanol（2：1） extraction and gas chromatography（GC） technology.Ma-rine microalga listed as IOAC689S was unique and suitable for biodiesel production because of its high total lipid content（37.5%） and its high content（91.03%） of short-chain fatty acids（carbon chain length shorter than 18）.To-tal ITS and 5.8S rDNA sequences of this alga were amplified;and a length of 998 bp DNA fragment including 18S rDNA and 28S rDNA sequences was obtained.The changes of net photosynthetic O2 evolution in IOAC689S under different culture conditions（including light intensity,temperature,pH,salinity,nitrate,phosphate and carbonate） were determined by an oxygen electrode.Optimized culture conditions were established（200 μmol/（m2？s） illumi-nation,30~35℃ in light and 24℃ in darkness,30‰ salinity,pH 7~9,75mg/L of NaNO3,40 mg/L of NaH2PO4）.NaHCO3 as carbon-source showed no significant effect on net photosynthetic O2 evolution.Under the optimized culture conditions,3.8 times biomass increase per week and 0.210 d？1 of average specific growth rate were observed for IOAC689S.In addition,the alga easily flocculated at the late cell culture stages when the culture pH was gradually adjusted to 10 or above.This flocculation can be used for biomass harvesting.