Glycerol metabolism in hypersaline environments

Glycerol is a key compound for the understanding of the microbiology of hypersaline environments. At the highest salt concentrations the main or even sole primary producer is the green unicellular alga Dunaliella, which uses photosynthetically produced glycerol as osmotic stabilizer and compatible solute. Glycerol can be expected to be a major carbon source available to the heterotrophic communities of Archaea and Bacteria in hypersaline ecosystems. Use of Dunaliella has even been explored for the commercial production of glycerol. This article reviews our current understanding of glycerol metabolism in Dunaliella and of the ways glycerol can be degraded by heterotrophic prokaryote communities under aerobic and under anaerobic conditions. Dunaliella-derived glycerol may also be the key toward long-term survival of heterotrophic prokaryotes in fluid inclusions within salt crystals.