دانلود رایگان مقاله بیوسنتز بتا کاروتن و تنظیم رونویسی ژن در قارچ بلیکسلیا تریسپورا

Abstract

The mold Blakeslea trispora is one of the most promising and economically attractive natural sources of β-carotene. In this study, the effects of sodium acetate (NaAC) on β-carotene content and production in mated B. trispora were investigated. The results show that the addition of acetate into mated medium could enhance β-carotene accumulation in B. trispora. The highest β-carotene content (59.91 mg/g dry biomass) and production (2130 mg/l) were obtained as adding 35 mM of NaAC at stationary phase, which were 77.7% and 80.5% increments compared with that of the control, respectively. Furthermore, the effects of NaAC on expression levels of carotenogenesis genes in mated B. trispora were investigated. The results show that addition of NaAC in mated medium caused the induction of five carotenogenesis genes expression (hmgR, carG, ipi, carRA, and carB) and promoted de novo synthesis of β-carotene. The induction of five genes expression exhibited sequential gene expression profiles and the five gene expression were ranging from 1.8 to 3.8 folds increment as early as 24 h after NaAC addition. We demonstrate that NaAC stimulation of β-carotene biosynthesis in mated B. trispora involved in change at genes transcriptional levels. Such regulatory mechanism provides an explanation for effect of NaAC on the biosynthesis of β-carotene in mated B. trispora.

4. Conclusion

The effects of adding sodium acetate into mated medium on biomass concentration, -carotene production and content of B. trispora were investigated under the batch cultivation. The addition of 35 mM of sodium acetate at stationary phase (72 h of fermentation) was more favorable for -carotene accumulation in B.trispora. The acetate regulation of -carotene biosynthesis in B. trispora involves expressional changes in five carotenoid biosynthetic genes (hmgR, ipi, carG, carRA, and carB) and five genes exhibited characteristics of sequential gene expression. These results provide the first molecular explanation for the role of acetate stimulation in carotene production in B. trispora. Adding 35 mM sodium acetate into mated medium was proved to be an effective method to enhance the -carotene production, giving the highest -carotene content,titer an productivity of 59.91 mg/g dry biomass, 2130 mg/l, and 355 mg/l/d, respectively, which are higher than most of the previously reported values. Ack