Haloarchaea have a high genomic diversity for the biosynthesis of carotenoids of biotechnological interest

Haloarchaea are mostly components of the microbial biomass of saline aquatic environments, where they can be a dietary source of heterotrophic metazoans or contribute to flamingo's plumage coloration. The diversity of secondary metabolites (SMs) produced by haloarchaea, which might play multiple ecological roles and have diverse biotechnological applications has been largely understudied. Herein, 67 haloarchaeal complete genomes were analyzed and 182 SMs biosynthetic gene clusters (BGCs) identified that encode the production of terpenes (including carotenoids), RiPPs and siderophores. Terpene BGCs were further analysed and it was concluded that all haloarchaea might produce squalene and bacterioruberin, which one a strong antioxidant. Most of them have other carotenoid BGCs that include a putative b-carotene ketolase that was not characterized so far in haloarchaea, but may be involved with canthaxanthin's biosynthesis. The production of bacterioruberin by Haloferax mediterranei ATCC 33500 was found to be not related to its antimicrobial activity. (c) 2021 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Automated summary

Haloarchaea are important components of saline aquatic environments and produce diverse secondary metabolites with potential ecological and biotechnological significance. This study analyzed 67 Haloarchaea genomes and identified multiple biosynthetic gene clusters involved in the production of terpenes, RiPPs, and siderophores. The findings suggest that all Haloarchaea might produce squalene and bacterioruberin, and some of them may have other carotenoid biosynthetic capabilities.