Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.
School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.
Appl Environ Microbiol. 2021 Feb 26;87(6). doi: 10.1128/AEM.02417-20.
Isoprene is a valuable petrochemical used for a wide variety of consumer goods, such as adhesives and synthetic rubber. We were able to achieve a high yield of renewable isoprene by taking advantage of the naturally high-flux mevalonate lipid synthesis pathway in anaerobic methane-producing archaea (methanogens). Our study illustrates that by genetically manipulating species methanogens, it is possible to create organisms that grow by producing the hemiterpene isoprene. Mass balance measurements show that engineered methanogens direct up to 4% of total carbon flux to isoprene, demonstrating that methanogens produce higher isoprene yields than engineered yeast, bacteria, or cyanobacteria, and from inexpensive feedstocks. Expression of isoprene synthase resulted in increased biomass and changes in gene expression that indicate that isoprene synthesis depletes membrane precursors and redirects electron flux, enabling isoprene to be a major metabolic product. Our results demonstrate that methanogens are a promising engineering chassis for renewable isoprene synthesis. A significant barrier to implementing renewable chemical technologies is high production costs relative to those for petroleum-derived products. Existing technologies using engineered organisms have difficulty competing with petroleum-derived chemicals due to the cost of feedstocks (such as glucose), product extraction, and purification. The hemiterpene monomer isoprene is one such chemical that cannot currently be produced using cost-competitive renewable biotechnologies. To reduce the cost of renewable isoprene, we have engineered methanogens to synthesize it from inexpensive feedstocks such as methane, methanol, acetate, and carbon dioxide. The "isoprenogen" strains we developed have potential to be used for industrial production of inexpensive renewable isoprene.
异戊二烯是一种有价值的石化原料，用于制造各种消费品，如粘合剂和合成橡胶。我们利用产甲烷古菌（甲烷菌）中天然高通量的甲羟戊酸脂质合成途径，实现了可再生异戊二烯的高产率。我们的研究表明，通过对产甲烷古菌的物种进行基因改造，有可能创造出能够通过产生半萜异戊二烯来生长的生物体。质量平衡测量表明，工程化的甲烷菌将高达 4%的总碳通量引导至异戊二烯，这表明甲烷菌产生的异戊二烯产量高于工程酵母、细菌或蓝藻，并且使用廉价的原料。异戊二烯合酶的表达导致生物量增加和基因表达的变化，表明异戊二烯合成会耗尽膜前体并重新引导电子流，从而使异戊二烯成为主要的代谢产物。我们的结果表明，甲烷菌是可再生异戊二烯合成的有前途的工程底盘。实施可再生化学技术的一个重大障碍是与石油衍生产品相比，生产成本较高。由于原料（如葡萄糖）、产品提取和纯化成本的原因，使用工程生物的现有技术难以与石油衍生化学品竞争。为了降低可再生异戊二烯的成本，我们已经设计了甲烷菌来利用甲烷、甲醇、醋酸盐和二氧化碳等廉价原料合成它。我们开发的“异戊二烯原”菌株有可能用于工业生产廉价的可再生异戊二烯。
