Ma Yingchao, Sun Zhongshi, Yang Huan, Xie Wei, Song Mengyu, Zhang Bo, Sui Liying
Key Laboratory of Marine Resource Chemistry and Food Technology (TUST), Ministry of Education, Tianjin University of Science and Technology, Tianjin, China.
Asian Regional Artemia Reference Center, College of Marine and Environmental Sciences, Tianjin University of Science and Technology, Tianjin, China.
Appl Environ Microbiol. 2024 Jul 24;90(7):e0054024. doi: 10.1128/aem.00540-24. Epub 2024 Jun 3.
Halophilic archaea are promising microbial cell factories for bacterioruberin (BR) production. BR is a natural product with multi-bioactivities, allowing potential application in many fields. In the previous work, a haloarchaeon sp. HRM-150 with a high proportion of BR (about 85%) was isolated, but the low yield impeded its large-scale production. This work figured out BR synthesis characteristics and mechanisms, and proposed strategies for yield improvement. First, glucose (10 g/L) and tryptone (15 g/L) were tested to be better sources for BR production. Besides, the combination of glucose and starch achieved the diauxic growth, and the biomass and BR productivity increased by 85% and 54% than using glucose. Additionally, this work first proposed the BR synthesis pattern, which differs from that of other carotenoids. As a structural component of cell membranes, the BR synthesis is highly coupled with growth, which was most active in the logarithm phase. Meanwhile, the osmotic down shock at the logarithm phase could increase the BR productivity without sacrificing the biomass. Moreover, the pathway for BR synthesis with a key gene of , and its competitive pathways (notably tetraether lipids and retinal) were revealed through genome, transcriptome, and osmotic down shock. Therefore, the BR yield is expected to be improved through mutant construction, such as the overexpression of key gene and the knockout of competitive genes, which need to be further explored. The findings will contribute to a better understanding of the metabolism mechanism in haloarchaea and the development of haloarchaea as microbial cell factories.
Recent studies have revealed that halophilic microorganism is a promising microbial factory for the next-generation industrialization. Among them, halophilic archaea are advantageous as microbial factories due to their low contamination risk and low freshwater consumption. The halophilic archaea usually accumulate long chain C carotenoids, which are barely found in other organisms. Bacterioruberin (BR), the major C carotenoid, has multi-bioactivities, allowing potential application in food, cosmetic, and biomedical industries. However, the low yield impedes its large-scale application. This work figured out the BR synthesis characteristics and mechanism, and proposed several strategies for BR yield improvement, encouraging halophilic archaea to function as microbial factories for BR production. Meanwhile, the archaea have special evolutionary status and unique characteristics in taxonomy, the revelation of BR biosynthesis mechanism is beneficial for a better understanding of archaea.
嗜盐古菌是生产细菌红素（BR）很有前景的微生物细胞工厂。BR是一种具有多种生物活性的天然产物，在许多领域具有潜在应用价值。在前期工作中，分离得到了一株细菌红素比例较高（约85%）的嗜盐古菌菌株HRM - 150，但产量较低阻碍了其大规模生产。本研究明确了BR的合成特性和机制，并提出了提高产量的策略。首先，经测试葡萄糖（10 g/L）和胰蛋白胨（15 g/L）是BR生产的更好碳源。此外，葡萄糖和淀粉的组合实现了双相生长，与单独使用葡萄糖相比，生物量和BR生产率分别提高了85%和54%。此外，本研究首次提出了BR的合成模式，这与其他类胡萝卜素不同。作为细胞膜的结构成分，BR的合成与生长高度耦合，在对数期最为活跃。同时，对数期的渗透压下降冲击可在不牺牲生物量的情况下提高BR生产率。此外，通过基因组、转录组和渗透压下降冲击揭示了BR合成途径及其关键基因，以及其竞争途径（特别是四醚脂质和视黄醛）。因此，有望通过构建突变体提高BR产量，如关键基因的过表达和竞争基因的敲除，这有待进一步探索。这些发现将有助于更好地理解嗜盐古菌的代谢机制，并推动嗜盐古菌作为微生物细胞工厂的发展。
最近的研究表明嗜盐微生物是下一代工业化很有前景的微生物工厂。其中，嗜盐古菌作为微生物工厂具有优势，因为它们污染风险低且淡水消耗少。嗜盐古菌通常积累长链C类胡萝卜素，这在其他生物中很少见。主要的C类胡萝卜素细菌红素（BR）具有多种生物活性，在食品、化妆品和生物医学行业具有潜在应用价值。然而，低产量阻碍了其大规模应用。本研究明确了BR的合成特性和机制，并提出了几种提高BR产量的策略，促使嗜盐古菌成为生产BR的微生物工厂。同时，古菌在分类学上具有特殊的进化地位和独特特征，揭示BR生物合成机制有助于更好地理解古菌。
