Microbial production of extremolytes - high-value active ingredients for nutrition, health care, and well-being.

Extremolytes are small organic molecules, which protect cells under extreme, virtually inhabitable conditions. Their exceptional properties can be translated into health-promoting and therapeutic activities, which open an avenue of opportunities for the cosmetic, medical, and food industries. Supported by powerful approaches from systems and synthetic biology and systems metabolic engineering, the bio-industry becomes more and more attracted to exploit this 'goldmine'. In addition to the well-established flagship ectoine, several novel extremolytes have emerged in the past years and high-efficiency cell factories have been created for bio-based extremolyte production. Here, we review recent prominent examples and success stories in the field.