[Effects of light quality on the growth characteristics and biochemical component of Chlorella pyrenoidosa].

Effect of light quality, including red light, blue light, white light, red and blue mixing light with ratios of 8: 1, 8:2 and 8 : 3, on the growth characteristics and biochenmical composition of Chlorella pyrenoidosa was investigated based on light emitting diode (LED). Results showed that Chlorella pyrenoidosa grew best under blue light, and the optical density, specific growth rate and biomass of Chlorella pyrenoidosa was about 2.4, 0.10 d(-1) and 0.64 g x L(-1), respectively, while the optical density of Chlorella pyrenoidosa was between 1.0 and 1.7, the specific growth rate was between 0.07-0.10 d(-1) and the biomass was between 0.27 and 0.38 g x L(-1) under other light quality after 30 days of cultivation. Under blue light, the optical density, specific growth rate and biomass of Chlorella pyrenoidosa was approximately 2.05 times, 1.33 times and 2.06 times higher than red light, respectively. Moreover, red and blue mixing light was conducive to the synthesis of chlorophyll a and ß-carotene of Chlorella pyrenoidosa, and blue light could promote the synthesis of chlorophyll b. Chlorophyll a and carotenoids content of Chlorella pyrenoidosa was 13.5 mg xg(-1) and 5.8 mg x g(-1) respectively under red and blue mixing light with a ratio of 8:1, while it was 8.4 mg x g(-1) and 3.6 mg x g(-1) respectively under blue light. Red and blue mixing light was more conducive to protein and total lipid content per dry cell of Chlorella pyrenoidosa. Protein and total lipid content was 489.3 mg x g(-1) and 311.2 mg x g(-1) under red and blue mixing light with a ratio of 8 : 3, while it was 400.9 mg x g(-1) and 231.9 mg x g(-1) respectively under blue light.

[Study on the Chlorella pyrenoidosa cultivation technology based on the excess sludge utilization].

Microalgae cultivation based on the waste water or other reused waste can not only make rational use of the waste, but also provide cheap materials for microalgae production. In the present study, Chlorella pyrenoidosa was used to develop a new way for microalgae cultivation based on the mix culture media with different ratio of sludge extracts and SE (selenite enrichment). Results showed that after 14 d cultivation under the same cultivating condition, the absorbency of C. pyrenoidosa at 680 nm was 0. 858 and 0. 845, respectively, when the ratio between culture medium of SE and sludge extracts was 1:9 and 2:8, and the absorbency at 680 nm was 0.247 and 0.571, respectively, when the ratio between culture medium of SE and sludge extracts was 0:10 and 10:0. Our results also demonstrated that highest content of chlororphyll, beta-carotene and protein was achieved in C. pyrenoidosa cultivated in the mix medium between SE and sludge extracts with the ratio of 2: 8. Therefore, sludge extracts can be used as a good medium to cultivate C. pyrenoidosa, and the C. pyrenoidosa grew much better in this mix medium than in SE medium. In this study, the best condition for C. pyrenoidosa cultivation was achieved in the mix medium with 80% sludge extracts, and C. pyrenoidosa grew very well and the content of chlororphyll and protein was also high in the microalgae cell in this mixture medium.