Availability, uptake and turnover of glycerol in hypersaline environments

A sensitive assay for glycerol and other polyols was developed, based on periodate oxidation to formaldehyde, followed by a colorimetric assay with 3-methyl-2-benzothiazolone hydrazone. Apparent glycerol concentrations thus measured in saltern crystallizer ponds were around 20-36 μM, while in the Dead Sea, during a Dunaliella bloom, values were up to 27 μM. However, these values probably overestimate the glycerol concentrations present, as shown by labeled glycerol uptake experiments. Values of [K + S_n] (natural concentration + affinity constant) in saltern ponds were as low as 0.76-1.4 μM, with V_max values of 193-303 nmol 1^-1h^-1, and turnover times between 2.6-7.2 h at 35°C. Similar measurements in the Dead Sea were: [K + S_n] 0.07-1.41 μM, V_max values 160-426 nmol 1^-1h^-1, and turnover times in the range of 0.45-3.3 h.