氮浓度对海绿球藻生长及总脂含量的影响

用叶绿素荧光分析技术和生物化学方法,研究了不同氮浓度0.22、0.44、0.66、0.88mmol/L(对照组)]对海绿球藻叶绿素荧光特性、细胞密度、叶绿素含量、相对生长率、干质量、总脂含量及总脂产率的影响。试验结果表明,第4～7d,0.22mmol/L处理组的主要荧光参数(光系统Ⅱ的最大光能转换效率Fv/Fm,光系统Ⅱ的潜在活性Fv/Fo,相对电子传递效率rETR,光系统Ⅱ的实际光能转化效率ΦPSⅡ)显著低于其他处理组。该藻的细胞密度、叶绿素a、b含量、相对生长率及干质量随起始氮浓度的增加而增加,0.22mmol/L处理组上述各项值最低,0.88mmol/L对照组上述各项值最高,其细胞密度、相对生长率和干质量分别为16.37×106个/ml,0.56、0.48g/L。0.22mmol/L处理组总脂含量(占干质量的41.84%)显著高于其他处理组,而对照组总脂含量仅为35.16%。总脂产率与起始氮浓度成正相关,0.22mmol/L处理组最低,仅为0.0095g/(L.d),而0.88mmol/L对照组总脂产率最高,为0.0189g/(L.d)。研究结果表明,氮浓度为0.22mmol/L最适合海绿球藻油脂的积累;氮浓度为0.88mmol/L最适合海绿球藻的生长。

Effects of Nitrogen Concentrations on Growth and Total Lipid Contents in Green Alga Halochlorococcum sarcotum

The effects of nitrogen concentrations(0.22 mmol/L,0.44 mmol/L,0.66 mmol/L,0.88 mmol/L and 0.00 mmol/L as control group) on chlorophyll fluorescence characteristics,cell density,chlorophyll content,relative growth rate,dry weight,total lipid contents and total lipid productivity were studied in green alga Halochlorococcum sarcotum by chlorophyll fluorescence technology and biochemical method to provide theorical basis for large-scale cultivation and biodiesel production of the alga.There were significantly lower main chlorophyll fluorescence parameters including Fv/Fm,Fv/Fo,rETR,and ΦPSⅡ in 0.22 mmol/L treatment than those in other treatments on days from 4 to 7.The cell density,chl a and chl b levels,relative growth rate and dry weight were found to be increased with the increase in the initial nitrogen concentration,the minimal values occurring in the 0.22 mmol/L treatment and the maximal values in the control group(cell density of 16.37×106/ml,relative growth rate of 0.56 and dry weight of 0.48 g/L).The alga cultured in 0.22 mmol/L treatment had significantly higher total lipid content(41.84% in dry weight) than the alga in other treatments(only 35.16 %) did.Total lipid productivity showed positive correlations with the initial nitrogen concentration,with the maximum value in the control group 0.0189 g/(L·d)] and the minimum in the 0.22 mmol/L treatment 0.0095 g/(L·d)],indicating that 0.22 mmol/L is the optimum nitrogen concentration for the lipid accumulation,and 0.88 mmol/L is the optimum nitrogen concentration for the alga growth.