The Effect Of Nutrient Elements On The Growth,astaxanthin Accumulation And Its Transcriptomes In Haematococcus Pluvialis

Haematococcus pluvialis is a freshwater species of Chlorophyta from the family Haematococcaceae. It could form haematocysts or aplanospores, and a high amount of astaxanthin is present in the cytosolic lipid bodies when the environmental conditions become unfavorable for normal cell growth, examples of such conditions include low availability of nutrients, high radiation and high salinity. In recent years, the researchs which for Haematococcus pluvialis and the accumulation and synthesis of astaxanthin of it are getting a lot of attention, because of astaxanthin has a very high resistance to oxidation, wide use range and great market potential. The lag of Haematococcus pluvialis breeding is resulted from the limiting of the studys for the life cycle of it and the interaction mechanisms of astaxanthin accumulation related genes and culture environment, due to the little understand for the genome or genetic background of Haematococcus pluvialis. Next-generation transcriptome sequencing technology has become the low-cost and important means to access genetic information, because of it could analyze the characteristics of bio transcriptome and its interaction with the environment without understanding the context of the genome.Based on the above reasons,the MAV( be made improvements) was used as basic medium to explore the life cycle and genes expression in the different growth stages of Haematococcus Pluvialis. In this study, to explore the life history of Haematococcus pluvialis and effects of nutrient elements on it, based on the morphological observation and the differentially gene expression in different growth stages. Next, through the single factor of different concentrations of N, P, Fe element processing, to explore the effect of N, P, Fe elements for the growth of algae and astaxanthin accumulation and the difference of gene expression. The research will provide the basic data for the Haematococcus pluvialis and nutrient elements in the study on the mechanism of interaction and pluvialis breeding.Experimental results are as follows :(1) Studies by adding different concentrations of N and P element to the medium, have shown that it was more suitable for the growth of Haematococcus pluvialis green growth stage when the concentrations of N and P were 62.37 mg/L and 3.396 mg/L, respectively; It was more suitable for the astaxanthin accumulation of Haematococcus pluvialis when the concentrations of N and P were 31.185 mg/L and 5.094 mg/L, respectively.(2) Studies by adding different concentrations of N, P and Fe element to the medium, have shown that it was most suitable for the biomass accumulation of Haematococcus pluvialis when the concentrations of N, P and Fe were 20.790 mg/L, 3.396 mg/L and 0.74518 mg/L, respectively; It was most suitable for the astaxanthin synthesis in Haematococcus pluvialis cells when the concentrations of N, P and Fe were 31.185 mg/L, 5.094 mg/L and 1.49036 mg/L, respectively; Continuous training model could get the maximum content of astaxanthin from a unit volume of medium when the concentrations of N, P and Fe were 20.790 mg/L, 3.396 mg/L and 0.74518 mg/L, respectively.(3) The exploration for Red growth cycle of Haematococcus pluvialis shows that Haematococcus pluvialis was found to grow and at the green growth stage under the condition of good growth environment; but stop to grow into the accumulation period and accumulate astaxanthin when environmental degradation is not suitable for survival. Its growth cycle could be artificially divided into: green growth stage → red accumulation stage(the middle changing period of green growth stage to red fixed stage) → red fixed stage → the middle changing period of red fixed stage to green growth stage → green growth stage. Transcriptome sequencing showed that there were 370 Unigene have differences between the green growth stage and red accumulation stage, in which green growth stage raised 210 Unigene, red accumulation stages raised 138 Unigene; there were 355 Unigene have differences between the red accumulation stage and red fixed stage, in which red accumulation stage raised 64 Unigene, red fixed stage raised 291 Unigene; there were 238 Unigene have differences between red fixed stage and the middle changing period of red fixed stage to green growth stage, in which red fixed stage raised 145 Unigene, the middle changing period of red fixed stage to green growth stage raised 291 Unigene(4) During the treatment processing of single factor of different concentrations of N, P, Fe element,the results from analysis of the transcriptome sequencing on Haematococcus pluvialis show that the difference in gene expression between the different growth stages of Haematococcus pluvialis among different elements treatment.