【作者】 孙辉；

【导师】 曹毅； 白林含；

【作者基本信息】 四川大学 ， 微生物学， 2005， 硕士

【摘要】 盐藻（Dunaliella）是一种极具经济学价值的单细胞绿藻,它主要分布在海洋、盐湖等盐水水体中,是目前世界上最耐盐的真核光合生物。它可以在多种胁迫条件下生长,主要是通过合成甘油和β—胡萝卜素来抵抗多种逆境。盐藻在逆境胁迫时可诱导合成大量β—胡萝卜素,这是盐藻综合抗逆的重要方面之一。β—胡萝卜素具有清除氧自由基的能力,是良好的抗氧化剂和氧化保护剂。积累β—胡萝卜素的盐藻对于这些逆境胁迫有着很强的抵抗能力,开展盐藻的生长特性及β—胡萝卜素的积累特性研究,对于了解盐藻的整个抗逆机制和综合抗逆水平具有深远的意义。本实验通过对不同胁迫下盐藻的生长特性和β—胡萝卜素积累的关系研究,确定β—胡萝卜素形成规律和机理,试验结果如下: 1.本文通过对盐藻的全波长扫描,确定了盐藻的最佳吸收波长为654nm,且单位体积盐藻细胞数量与OD_654nm的光吸收值呈线性相关。解决了目前国内外关于盐藻细胞光吸收值报道不一的问题。 2.针对盐藻具有的综合抗逆生物学特性,研究了杜氏藻属七个种的酸碱耐受性、极端温度耐受性、耐强光和氮磷比对生长特性影响等问题,发现D.parva的耐酸性最强,可在pH5.0条件下生存;而D.painolate和D.parva的耐碱性最强（pH9.0）;D.sp的耐热性较强（45℃）,D.parva的抗寒性较强（4℃）。每个种生长的最适氮磷比不相同,其中D.bardawil、D.sp、D.painolate、D.salina的最适氮磷比为30,D.bioculate、原种D.salina、D.parva的最适氮磷比为50。为下一步抗逆基因的克隆以及β—胡萝卜素高产奠定了基础。 3.首次系统分析了八种胁迫条件（高盐、高渗、强光、氧化剂、紫外、缺氮、缺磷、缺硫）下,盐藻β—胡萝卜素积累的变化趋势,发现在高盐振荡2-4h、高渗振荡2h、氧化剂处理0.5h、强光(1500μE·m^-2s^-1)照射1h、紫外光照射更多还原

【Abstract】 Dunaliella salina is a valuable unicellular halotolerant green alga. It mostly distribute in some salt fields and oceans, is the most extreme halotolerant alga in the world. The halotolerant chlorophyta Dunaliella salina is well known due to its ability to produce large quantities of β -carotene under defined conditions of stress. By common consent, it is a natural source to produce β -carotene. The present study is important to understand the whole stress-resistant machanism and the level of mutiple stress-resistant in Dunaliella. Through exploring under the stress the relation of growth properties with β -carotene accumulation of Dunaliella, we determined the β -carotene formed rule and machanism. The result showed: (1) This study scaned the wavelenth of D.salina, confirmed that it has optimum absorbance in 654nm. The number of D.salina cells per unit volume is relative with its absorbance of 654nm in correlation function. (2) We have studied Dunaliella’s bfological properties, included its tolerance in different pH, its growth under 10-60 N/P. This report can give us a general idea of the state of Dunaliella’s live in a higher temperature, a cool environment and without illumination. (3) This study investigates cell growth and accumulation of β -carotene of D.salina, were established basis on series of experiment with different concentration under the normal conditions. Results showed that the algal cellular maximum content of β-carotene was obtained at defined stress conditions. The β-carotene /chlorophyll ratio arrived the largest value, but its growth rate is limited under these condition. Based on the above results, the controlled mechanism and its effect on these stressfor available cell accumulation of β-carotene was thus discussed. (4) We analysis that β -carotene accumulation of seven strains Dunaliella in different stress conditions. The seven strains were grown in such culture conditions to examine the different β-carotene production. So we can further investigate the rule of β -carotene accumulation in these stress, and select the best valuable strain in commercial production of β -carotene. (5) In order to explore the molecular mechanism of D.salina β -carotene accumulation, we studied that the protein expression difference in some physiological stress which β -carotene accumulation is highest. We report a 15kD special strip in these conditions, initially confirm it is relate with β-carotene accumulation.更多还原