Owing to the increase in energy consumption, fossil fuel resources are gradually depleting which has led to the growing environmental concerns; therefore, scientists are being urged to produce sustainable and ecofriendly fuels. Thus, there is a growing interest in the generation of biofuels from renewable energy resources using microbial fermentation. Butanol is a promising biofuel that can substitute for gasoline; unfortunately, natural microorganisms pose challenges for the economical production of 1-butanol at an industrial scale. The availability of genetic and molecular tools to engineer existing native pathways or create synthetic pathways have made non-native hosts a good choice for the production of 1-butanol from renewable resources. Non-native hosts have several distinct advantages, including using of cost-efficient feedstock, solvent tolerant and reduction of contamination risk. Therefore, engineering non-native hosts to produce biofuels is a promising approach towards achieving sustainability. This paper reviews the currently employed strategies and synthetic biology approaches used to produce 1-butanol in non-native hosts over the past few years. In addition, current challenges faced in using non-native hosts and the possible solutions that can help improve 1-butanol production are also discussed. Non-native organisms have the potential to realize commercial production of 1- butanol from renewable resources. Future research should focus on substrate utilization, cofactor imbalance, and promoter selection to boost 1-butanol production in non-native hosts. Moreover, the application of robust genetic engineering approaches is required for metabolic engineering of microorganisms to make them industrially feasible for 1-butanol production.

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用于 1-丁醇生产的非天然宿主的基因工程及其挑战：综述

由于能源消耗的增加，化石燃料资源逐渐枯竭，环境问题日益突出；因此，科学家们被敦促生产可持续且环保的燃料。因此，人们对利用微生物发酵从可再生能源生产生物燃料越来越感兴趣。丁醇是一种很有前景的生物燃料，可以替代汽油；不幸的是，天然微生物对工业规模经济生产1-丁醇提出了挑战。用于设计现有天然途径或创建合成途径的遗传和分子工具的可用性使得非天然宿主成为利用可再生资源生产 1-丁醇的良好选择。非本地宿主具有几个明显的优势，包括使用具有成本效益的原料、耐溶剂性和降低污染风险。因此，改造非本地宿主来生产生物燃料是实现可持续发展的一种有前途的方法。本文回顾了过去几年目前在非天然宿主中生产 1-丁醇所采用的策略和合成生物学方法。此外，还讨论了当前使用非本地宿主所面临的挑战以及有助于提高 1-丁醇产量的可能解决方案。非本地生物具有利用可再生资源实现1-丁醇商业化生产的潜力。未来的研究应重点关注底物利用、辅因子失衡和启动子选择，以提高非本地宿主中 1-丁醇的产量。此外，微生物的代谢工程需要应用强大的基因工程方法，使其在工业上可用于1-丁醇生产。