Transcriptome Analysis Of Production Astaxanthin Induced By High Light In Haematococcus Pluvialis

Astaxanthin is an oxygen-containing derivative of carotenoids.Natural astaxanthin has strong antioxidant activity.It has been widely used in many fields such as medicine,health products,cosmetics and aquaculture.Haematococcus pluvialis is the best source of natural astaxanthin.The production of astaxanthin by Haematococcus pluvialis has a important value and broad prospects for development.Therefore,excavated genes related to astaxanthin metabolism by transcriptome and improvement the production of astaxanthin in Haematococcus pluvialis are great significance.In this study,we identified the strain FACHB712 as Haematococcus pluvialis by morphological and molecular biology identification.Through pouring and streaking plate technique,capillary microscopic separation and combined with antibiotic sterilization methods,we obtained the aseptic algae strain.By comparing the storage effects of liquid,solid-liquid,low temperature glycerol/dimethyl sulfoxide storage method,the solid-liquid two-phase preservation method was the best,Low temperature preservation was the worst,and cells preserved by low concentration of protectant could not survive.The stress results of light,temperature,nitrogen and phosphorus on Haematococcus pluvialis showed that all stress factors inhibited the growth of the algae,even caused a large number of cells death,but promoted astaxanthin accumulation.The contents of astaxanthin are 12.919 mg/g·dw under 10 000 Lux strong light stress 25 days,22.80 times as that of the control group.The optimum temperature for astaxanthin accumulation was 25?,the maximum value was 7.183 mg/g·dw,8.87 times as that of the control group.Under nitrogen and phosphorus deficiency stress,the maximum content of astaxanthin was 7.419 mg/g·dw and 4.780 mg/g·dw,respectively.At the same time,the content of astaxanthin in the control group was only 0.638 mg/g·dw.Transcriptome sequencing was performed on the samples of high light stress and control in different periods.The original sequence is processed by quality evaluation,filtering and Splicing,41887 unigenes were obtained and annotated using NR,NT,GO,KOG,eggNOG,Swiss Prot and UniProt_trembl databases.Differential expression analysis was carried out on the 5th and 15 th day of high light stress.The results showed that 2609 up-regulated genes,10259 down-regulated genes.4703 up-regulated genes and 17197 down-regulated genes were obtained by differential expression analysis on the 15 th day of high light stress and the 15 th day of control.GO and KEGG enrichment analysis were performed on the differentially expressed genes.Finally,the excavated key enzyme genes and transcription factors related to astaxanthin metabolism,Selection of 13 differentially expressed genes were validated by qRT-PCR,and the results are consistent with the sequencing analysis.The content of astaxanthin increased by 61.71%,54.68%,56.24% and 51.22% respectively in four mutants A21,A31,A34 and A35 mutagenesis by ARTP.