Mustila Henna, Kugler Amit, Stensjö Karin
Microbial Chemistry, Department of Chemistry-Ångström Laboratory, Uppsala University, SE-751 20, Uppsala, Sweden.
Metab Eng Commun. 2021 Jan 23;12:e00163. doi: 10.1016/j.mec.2021.e00163. eCollection 2021 Jun.
Cyanobacteria can be utilized as a platform for direct phototrophic conversion of CO to produce several types of carbon-neutral biofuels. One promising compound to be produced photobiologically in cyanobacteria is isobutene. As a volatile compound, isobutene will quickly escape the cells without building up to toxic levels in growth medium or get caught in the membranes. Unlike liquid biofuels, gaseous isobutene may be collected from the headspace and thus avoid the costly extraction of a chemical from culture medium or from cells. Here we investigate a putative synthetic pathway for isobutene production suitable for a photoautotrophic host. First, we expressed α-ketoisocaproate dioxygenase from (KICD) in . We discovered isobutene formation with the purified KICD with the rate of 104.6 ± 9 ng (mg protein) min using α-ketoisocaproate as a substrate. We further demonstrate isobutene production in the cyanobacterium sp. PCC 6803 by introducing the KICD enzyme. strain heterologously expressing the KICD produced 91 ng l OD h. Thus, we demonstrate a novel sustainable platform for cyanobacterial production of an important building block chemical, isobutene. These results indicate that KICD can be used to further optimize the synthetic isobutene pathway by protein and metabolic engineering efforts.
蓝藻可被用作将CO直接光养转化以生产多种类型碳中性生物燃料的平台。一种有望在蓝藻中通过光生物学方式生产的化合物是异丁烯。作为挥发性化合物，异丁烯会迅速从细胞中逸出，不会在生长培养基中积累到有毒水平，也不会被困在细胞膜中。与液体生物燃料不同，气态异丁烯可以从顶空收集，从而避免从培养基或细胞中提取化学物质的高昂成本。在这里，我们研究了一种适合光合自养宿主的异丁烯生产假定合成途径。首先，我们在[具体物种]中表达了来自[具体物种]的α-酮异己酸双加氧酶（KICD）。我们发现，以α-酮异己酸为底物，纯化后的KICD能形成异丁烯，速率为104.6±9纳克/（毫克蛋白质·分钟）。我们通过引入KICD酶进一步证明了在蓝藻PCC 6803中能生产异丁烯。异源表达KICD的[具体菌株]产生了91纳克/（升·光密度·小时）。因此，我们展示了一个用于蓝藻生产重要基础化学物质异丁烯的新型可持续平台。这些结果表明，KICD可用于通过蛋白质和代谢工程手段进一步优化异丁烯合成途径。
