Abstract:

The traditional chemical manufacturing based on petroleum as raw material has had profound impacts in the development of modern society. However, it also has many drawbacks, such as environmental pollution and lack of sustainability. In contrast, biomanufacture with microorganisms as industrial chassis is gradually becoming a hot spot in industrial production due to its advantages of environmental friendliness and sustainability.Nonetheless, the limitations of traditional industrial biotechnology, including susceptibility to microbial contamination, complex fermentation processes, and difficulties in achieving continuous fermentations, have hindered the competitiveness of their products in terms of production costs compared to chemical industries To address these challenges, "Next Generation Industrial Biotechnology (NGIB)" with extremophiles as non-conventional chassis, has been undergoing continuous development with increasing global attentions.The basis of NGBI is extremophiles, such as halophiles, acidophiles, and thermophiles, known for their ability to thrive in extreme environments. Through molecular engineering of extremophiles, especially Halomonas spp., the recombinants can utilize various inexpensive carbon sources for continuous open fermentation, leading to the production of diverse high-value products with reduced cost. This review defines and summarizes the characteristics of extremophiles, highlighting their ability to grow rapidly in extreme environments like high salt, high temperature, and extreme pH. Subsequently, the review summarizes current genetic engineering approaches for extremophiles, such as promoter engineering, CRISPR-based gene editing, community fate strategy, and stable plasmid vectors. Additionally, metabolic engineering methods such as precursor supplementation, pathway disruption, byproduct reduction, and enhanced transport are discussed, along with various products including PHA, proteins, amino acids, and small molecule derivatives. The review also identifies challenges in extremophile engineering, such as the lack of suitable plasmid vectors, low plasmid transformation efficiency, lack of efficient gene editing tools, and long growth and fermentation cycle, proposing corresponding solutions. Finally, the review proposes leveraging the characteristics of different types of extremophiles to produce advantageous products, thereby driving the development of next generation industrial biotechnology based on various extremphiles, and achieving green, environmentally friendly, and sustainable biomanufacturing.

Key words: Extremophiles, Halomonas, Next-generation industrial biotechnology, Bioproduction, PHB, Genetic engineering, Metabolic engineering, Synthetic biology, Unsterile fermentation, Non-food substrates

摘要：

以微生物或酶为基础的生物制造，正以其绿色、环保、可持续等优势逐渐替代以化石燃料为原料的传统化工生产模式。然而，传统工业生物技术在易染菌、设备复杂、难以连续发酵等劣势。相较而言，“下一代工业生物技术（NGIB）”利用以嗜盐菌、嗜热菌和嗜酸碱菌等极端微生物作为底盘细胞，使用廉价底物生产多种高附加值产品，具有开放、无需灭菌、连续发酵等优点。本文介绍了嗜盐菌、嗜热菌和嗜酸碱菌极端微生物的定义以及在高盐、高温极度酸碱等极端环境下快速生长的特性。随后总结了目前极端微生物的基因工程手段例如启动子工程、以CRISPR为代表的基因编辑技术、命运共同体策略、稳定质粒载体等，代谢工程手段例如增加碳源前体、敲除旁路代谢、减少副产物、提高转运等，以及极端微生物生产的多种产品例如PHA、蛋白质、氨基酸及小分子衍生物等。同时概况了目前在极端微生物底盘细胞改造过程中仍存在的问题，如缺乏多种优秀的质粒载体、质粒转化效率低、缺乏高效基因编辑技术以及其他非嗜盐菌生长发酵周期较长等，并提出了相应的解决策略。最后展望了如何充分利用不同类型极端微生物的特性生产优势产品，推动下一代工业生物技术的发展与完善，实现绿色、环保、可持续的生物制造。

关键词: 极端微生物, 嗜盐菌, 下一代工业生物技术, 生物制造, PHB, 基因工程, 代谢工程, 合成生物学, 无灭菌发酵, 非粮生物原料