小球藻磷吸收的初步研究

Preliminary study on the phosphorus absorption of Chlorella vulgaris

将经过磷饥饿的小球藻(Chlorella vulgaris)接入不同初始磷质量浓度的培养基中进行一次性培养,研究磷对小球藻生长的影响,以及小球藻吸收磷的动力学特征和藻体总磷、水中可溶性磷的变化规律。结果表明,小球藻密度随初始磷质量浓度增加而增加。5个磷酸盐质量浓度组中,磷质量浓度为0.047 mg/L和0.155 mg/L组的小球藻延滞期长,对数期和稳定期均明显短于0.47 mg/L、0.775 mg/L和2.48 mg/L组。中高磷质量浓度组小球藻平均比生长率μa和最大比生长率μm明显高于低磷组。根据拟合的Monod方程和Droop方程,磷酸盐影响下小球藻最大比增长率μm为0.377/d,半饱和常数Ks为0.311 mg/L,最小细胞内磷份额Q0为73μg/mg(干重)。小球藻细胞的生长主要取决于细胞内磷含量,藻细胞利用外源性磷有快速吸收和缓慢吸收两个过程。

The given article is to present the results of our investigation for the effects of the phosphorus on the growth of Chlorella vulgaris and the mechanism of phosphorus absorption on the condition when phosphate-starvation C. vulgaris is inoculated in the cultural media with different initial phosphorus concentrations.For the research purpose,we have put our study focus on the growth curves,the variation regularities of the intracellular phosphorus,as well as the soluble phosphate contents in the aquarial media. The results of our investigation have shown that the algal density tends to increase with the increase of the initial phosphorus concentration. On the other hand,the growth of C. vulgaris tends to be inhibited if the phosphorus concentration stays too low,though the high concentration of phosphate may not promote C. vulgaris growth in the later phases. Besides,the research experience tells us that, of the five phosphorus concentration groups,the lag phase of 0. 047 mg/L and that of 0. 155 mg/L of the phosphorus concentration groups may turn to be longer,whereas the logarithmic and stationary phases tend to be much shorter than those of 0. 47 mg/L,0. 775 mg/L and 2. 48 mg/L groups. In spite of this,the average specific growth rate（ μa）and the maximum specific growth rate（ μm） of C. vulgaris in higher phosphorus concentration groups are remarkably higher than those in the low phosphorus groups. Besides,Monod equation can help to disclose the relationship between C. vulgaris growth and phosphorus concentration. As the result of our studies,we have worked out the semi-saturation constant（ Ks） andμm,which represent the growing effects of phosphorus according to the experimental results. Experimentally speaking,in accordance with Monod fitting equation,μmand Kshave been found equal to 0. 377 d（-1）and 0. 311 mg/L,respectively. In addition,the establishment of Droop equation helps us to find that the lowest restrictive phosphorus quota（ Q0） should be equal to 73μg/mg. In addition,we have also found that the growth of the algae cells turns to be dependent mainly on the intracellular phosphorus content. However,the intracellular phosphorus has been found higher at the lag and logarithmic phases than at the stationary phase. What is more,the algal cells can utilize the exogenous phosphorus through rapid absorption and slow absorption. Thus,it can be concluded that the aqueous phosphorus concentration may not tend to be a limited factor for the growth of C. vulgaris in our experiments with phosphorus mass concentration being 2. 48 mg/L.