Screening Of Elite Strains Of Haematococcus Pluvialis And Its Physiological Characteristics

Haematococcus pluvialis is a freshwater single cell green alga.The red cells of H. pluvialis can accumulate large amount of astaxanthin,which makes this species an ideal source for astaxanthin production. Astaxanthin is a strong colorant and it has powerful anti-oxidative ability. Therefore,it has a broad application in health products industry,food industry, cosmetic product industry and breeding industry.In the process of producting astaxanthin by H. pluvialis, the screening of excellent strains and clarifying its growth and physiological characteristics are important. In this paper, using ten strains of H. pluvialis as experimental materials,comparing the biomass and astaxanthin contents of them, selecting the excellent strain, which has higher level of biomass and astaxanthin contents.Further analyzing the growth and physiological characteristics of it. The main results as follows:1. Compared the biomass and astaxanthin contents often strains of H.pluvialis,the H. pluvialis CG-06 was selected as the excellent strain, the maximum biomass achieved 2.61 g/L and the astaxanthin content was 2.99mg/g, which were higher than other strains.On contrary, the maximum biomass (1.98 g/L) and the astaxanthin (2.36mg/g) of H. pluvialis CG-04 were lower than other strains obviously.2. H. pluvialis CG-04 was used as reference, the growth and physiological characteristics of two strains were investigated without stress.The results showed that:l) The pigment compositions included chlorophyll, lutein,β-carotene,astaxanthin,echinenone and canthaxanthin,the contents of chlorophylla (5.23 mg/g) and astaxanthin (2.56mg/g) of CG-06 were more than CG-04(2.17 mg/g and 2.18 mg/g);2) The astaxanthin were detected in two H. pluvialis cultures in the 7th day, the contents were 0.104mg/g and 0.122mg/g, and then the nitrogen concentrations had declined to 0.169 mg/L and 0.338 mg/L respectively.3)Compared the physiological characteristics between two stains, the photosynthetic rate, Fv/Fm, Yield and qP of two strains decreased while that the respiration rate and NPQ increased.However, the photosynthetic rate,Yield and qP of H. pluvialis CG-04 were lower than CG-06, the NPQ were higher than it.This significant difference in the physiological characteristics indicated that the activity of reaction center of PSⅡ,the efficiency of electron transfer of photosystems and the efficiency of carbon assimilation of H. pluvialis CG-06 were higher;4)The malondialdehyde(MDA) contents of CG-04 (0.89nmg/mL) was higher than CG-06 (0.81nmg/mL);5)Quqdripartition,which was the special pattern of cell proliferation was observed in CG-06 by optical microscope,but the same phenomenon was not found in CG-04.3. The responses of two strains to the stress of high salinity and high light intensity were different. H. pluvialis CG-06 had stronger stress-resistance than H. pluvialis CG-04. The decreased amplitude in chlorophyll contents, Fv/Fm and photosynthetic rate of (46.8%,40.4%,42.9%) were lower than them of CG-04(50.1%,45.9%,45.4%),while the astaxanthin contents of CG-06 (2.94mg/g)was higher than CG-04(2.49mg/g).There had differences in MDA contens, the MDA contents of CG-04 (0.71nmg/mL) was higher than CG-06 (0.60nmg/mL).