不同光照模式对卷枝毛霉类胡萝卜素合成及相关基因表达的影响

Effects of Different Light Treatments on Carotenoid Biosynthesis and Related Gene Expression in Mucor circinelloides

为探究不同光照模式对卷枝毛霉(Mucor circinelloides)类胡萝卜素合成的影响,在持续恒定光照、光暗交替和逐步提高光强3种不同蓝光照射条件下培养卷枝毛霉菌株CBS 277.49,观察不同培养时间(0、6、12、18 h和24 h)的菌落形态,测定生物量和类胡萝卜素含量,并通过实时荧光定量聚合酶链式反应(quantitative real-time polymerase chain reaction,qRT-PCR)确定蓝光感受器编码基因mcwc-1c以及类胡萝卜素合成结构基因carB和carRP的表达情况,以黑暗处理作为对照组。结果表明:3种光照模式均能促进卷枝毛霉CBS 277.49的生长,并且提高其类胡萝卜素产量。但持续恒定蓝光照射使卷枝毛霉在12 h后产生“光适应”,蓝光感受器编码基因mcwc-1c以及类胡萝卜素合成结构基因carB和carRP表达量均明显下降,类胡萝卜素合成停滞。光暗交替和逐步提高光强两种光照模式则因为在培养过程中光强随时间不断变化,避免了"光适应"的产生,因此,能够保持结构基因以较高水平表达,使类胡萝卜素持续积累。在该研究考察光强和培养时间范围内,光暗交替处理组的类胡萝卜素终产量最高,达(3 728.78±48.09)μg/g。

The effects of different light treatments on the carotenoid biosynthesis of Mucor circinelloides were studied.The CBS 277.49 strain of M.circinelloides was cultured under three different blue light irradiation conditions:continuous constant light,alternating light and dark,and gradually increased light intensity.The morphology of colonies cultured for different time periods(0,6,12,18,24 h)was observed,and the biomass and carotenoid content were measured.The expression of the blue light receptor encoding gene mcwc-1c and the genes car B and car RP involved in carotenoid synthesis were determined by RT-q PCR,with a sample exposed to dark treatment serving as the control group.The results showed that all the three light patterns promoted the growth and increased the carotenoid yield of M.circinelloides CBS 277.49.However,continuous constant blue light exposure caused light adaptation after 12 h.In addition,this light pattern down-regulated the expression of mcwc-1c,car B and car RP,causing stagnation of carotenoid synthesis.The other two light patterns with changing light intensity during the culture process avoided the occurrence of light adaptation,which ensured the high expression of relevant genes and the continuous accumulation of carotenoids.Within the ranges of light intensity and incubation time,the alternating light and dark pattern showed the highest carotenoid yield,which reached(3 728.78±48.09)μg/g.