School of Chemical Engineering & Technology, Tianjin University, Tianjin, 300072, People's Republic of China.
Biotechnol Biofuels. 2012 Dec 21;5(1):89. doi: 10.1186/1754-6834-5-89.
Fermentation production of biofuel ethanol consumes agricultural crops, which will compete directly with the food supply. As an alternative, photosynthetic cyanobacteria have been proposed as microbial factories to produce ethanol directly from solar energy and CO2. However, the ethanol productivity from photoautotrophic cyanobacteria is still very low, mostly due to the low tolerance of cyanobacterial systems to ethanol stress.
To build a foundation necessary to engineer robust ethanol-producing cyanobacterial hosts, in this study we applied a quantitative transcriptomics approach with a next-generation sequencing technology, combined with quantitative reverse-transcript PCR (RT-PCR) analysis, to reveal the global metabolic responses to ethanol in model cyanobacterial Synechocystis sp. PCC 6803. The results showed that ethanol exposure induced genes involved in common stress responses, transporting and cell envelope modification. In addition, the cells can also utilize enhanced polyhydroxyalkanoates (PHA) accumulation and glyoxalase detoxication pathway as means against ethanol stress. The up-regulation of photosynthesis by ethanol was also further confirmed at transcriptional level. Finally, we used gene knockout strains to validate the potential target genes related to ethanol tolerance.
RNA-Seq based global transcriptomic analysis provided a comprehensive view of cellular response to ethanol exposure. The analysis provided a list of gene targets for engineering ethanol tolerance in cyanobacterium Synechocystis.
生物燃料乙醇的发酵生产消耗了农作物，这将直接与粮食供应竞争。作为替代方案，光合蓝藻已被提议作为微生物工厂，直接利用太阳能和 CO2 生产乙醇。然而，光自养蓝藻的乙醇生产率仍然很低，这主要是由于蓝藻系统对乙醇胁迫的耐受性低。
为了构建工程化耐乙醇产乙醇蓝藻宿主的基础，在这项研究中，我们应用了一种定量转录组学方法，结合下一代测序技术，以及定量逆转录 PCR（RT-PCR）分析，来揭示模型蓝藻集胞藻 PCC 6803 中对乙醇的全局代谢反应。结果表明，乙醇暴露诱导了参与常见应激反应、运输和细胞包膜修饰的基因。此外，细胞还可以利用增强的聚羟基脂肪酸酯（PHA）积累和乙醛酸解毒途径来应对乙醇胁迫。转录水平进一步证实了乙醇对光合作用的上调。最后，我们使用基因敲除菌株来验证与乙醇耐受性相关的潜在靶基因。
基于 RNA-Seq 的全局转录组分析提供了细胞对乙醇暴露反应的全面视图。该分析为工程化蓝藻集胞藻乙醇耐受性提供了一组基因靶标。
