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 muM, while in the Dead Sea, during a Dunaliella bloom, values were up to 27 muM. 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 muM, with V(max) values of 193-303 nmol l-1 h-1, and turnover times between 2.6-7.2 h at 35-degrees-C. Similar measurements in the Dead Sea were: [K+S(n)] 0.07-1.41 muM, V(max) values 160-426 nmol l-1 h-1, and turnover times in the range of 0.45-3.3 h.