ABSTRACT
Extremophiles include microorganisms that grow optimally at extremes of temperature, salinity, pH, and radiation exposure. Some of these are pathogens, particularly those involved in food spoilage. Others produce enzymes used for diagnostics, for example, DNA polymerases and enzymes in biosensors. However, their main interest is as producers of secondary metabolites with medical applications. Both deep-sea and terrestrial extremophiles produce a wide range of secondary metabolites under investigation for their anticancer and antimicrobial properties. While some compounds derived from marine organisms have been used to make anticancer drugs, not all these sources are technically extremophilic, unless they are derived from cold waters. Terrestrial acidophiles found in Berkeley Pit Lake produce many compounds with cytotoxic and antimycobacterial properties. Extremophiles produce molecules that can be used to make nanoparticles, applicable to drug and gene delivery and diagnostic imaging, or produce these intracellularly. Thermophilic and halophilic archaea produce characteristic lipids that can be used to make archaeosomes, which can be used for the oral delivery of biologically active peptides. Radiation-resistant extremophiles produce primary and secondary metabolites for protection, the best characterized of which are scytonemin and mycosporine-like amino acids (MAAs), which are components of some commercially available sunscreens. Many halophiles produce low-molecular-weight solutes that provide osmotic balance. Ectoine, produced by various halophiles, is produced on an industrial scale for pharmacological applications, particularly as a moisturizer and a component of anti-inflammatory products. The full medical potential of extremophile-derived products has yet to be reached.
