重要理化因子对小球藻生长和油脂产量的影响

The effects of physical and chemical factors on the growth and lipid production of Chlorella

采用通气培养的方法研究了N、P、Fe3+、盐度、光照强度、温度对小球藻(Chlorella sp.XQ-200419)生长速率、生物量和油脂产量的影响。主要结果如下:N浓度对小球藻的生长和油脂产量均有显著的影响,在KNO3浓度0.05—0.3g/L范围内,小球藻生长速率随N浓度的增加而提高,并积累更多的生物量,而油脂含量随之递减,KNO3浓度为0.3g/L时,油脂产量最高。小球藻对P浓度变化的适应范围很大,K2HPO4浓度在10—160mg/L范围内,对小球藻的生长和油脂产量都没有显著影响。在小球藻培养后期补加不同浓度Fe3+对其生长速率没有显著影响,总脂含量随着Fe3+浓度升高呈现上升的趋势,均比对照有极显著提高,Fe3+浓度为0.75mmol/L时油脂产量最高。盐度对小球藻的生长有一定的抑制作用;油脂含量先随着盐度的增大而提高,当NaCl浓度达到0.6mol/L,油脂含量又显著降低;油脂含量和油脂产量均在盐度为0.2mol/L时最高。光照强度对处于生长后期的小球藻的生长影响不大,但影响其油脂积累,小球藻的油脂含量和产量随光照强度的增大而显著提高,当光照强度增至280μmol m-2s-1时,油脂含量和油脂产量最高。温度对小球藻的生长速率、生物量、油脂含量和油脂产量都有显著的影响,在15—40℃范围内,随着培养温度的升高,生长速率、生物量、油脂含量和油脂产量都经历了一个先上升然后下降的过程,适合小球藻生长、积累油脂的温度范围是20—35℃,30—35℃时油脂产量最高,40℃时生物量、油脂含量和产量都最低。理化因子对生长和油脂含量的影响分为两种情况:(1)温度、光强、铁浓度和盐度的影响表现为在适宜生长的条件下提高油脂含量,这种模式可以称为"适宜模式";(2)氮浓度的影响表现为在不利于生长的条件下提高油脂含量,这种模式可以称为"胁迫模式"。两种模式都可以提高油脂含量,但是,只有适宜模式才可以提高油脂产量。在筛选小球藻优良产油藻种时要注意,只有在适宜的培养条件下油脂含量高的藻种才具有高产油潜力。

The effects of nitrogen,phosphorus,iron,salinity,light intensity,and temperature on the growth rate,biomass,and lipid accumulation of Chlorella sp.XQ-200419 in aerated cultures were investigated.The main results are as follows： Both the growth and lipid accumulation of Chlorella sp.XQ-200419 are significantly affected by the nitrogen concentration in the BG11 medium.Growth rate and biomass increase with increasing KNO3 concentration from 0.05g/L to 0.3g/L,however lipid content decreases.Maximum lipid production was realized when the KNO3 concentration was 0.3g/L.There were no obvious effects on the growth and lipid accumulation of Chlorella sp.XQ-200419 when the K2HPO4 concentration ranged from 10 mg/L to 160mg/L.The growth rate was not affected by supplementing the growth media with chelated FeCl3 in the late growth phase.whereas,the lipid content did increase with increasing supplemented Fe3＋ concentration.Both the lipid content and lipid production were maximized when cultures were supplemented with 0.75mol/L Fe3＋.Growth of Chlorella sp.XQ-200419 was inhibited to some extent by salinity.With NaCl concentrations of 0.2mol/L or less,the lipid content increases with the increases in salinity.When the NaCl concentration was 0.6mol/L,the lipid content declined significantly.Lipid content and lipid production both were maximized with a NaCl concentration of 0.2mol/L.The growth of Chlorella sp.XQ-200419 was only slightly affected by changing the light intensities in the late growth phase.However,lipid accumulation was greatly affected.Lipid content and lipid production significantly increased with the increased light intensity.Maximal lipid content and lipid production were achieved at the highest light intensity used 280μmol m-2s-1.Temperature significantly impacted growth rate,biomass,lipid content,and lipid production.With the increases in temperature from 15℃ to 40℃,the growth rate,biomass,lipid content and lipid production all initially increased and then decreased.The optimal temperature range for growth and lipid accumulation is from 20℃ to 35℃.Lipid production was maximized between 30℃ and 35℃.Cultivation at 40℃ caused minimal biomass,lipid content,and lipid production.There are two patterns by which physical and chemical factors act on the growth and lipid content of Chlorella sp.XQ-200419.When temperature,light intensity,Fe3＋ and salinity are applied at an optimal range they have a promoting effect on both growth and the lipid content of the alga,which can be termed as ＂fit mode＂.In the second pattern,low nitrogen concentration leads to an increased lipid content but inhibits the growth of the alga.This is termed ＂stress mode＂.Both modes increase lipid content,but only the ＂fit mode＂ increases lipid production.To select good oil-producing strains of Chlorella,it is also worth noting that only strains that achieve higher oil content under suitable culture conditions have high potential for oil production.