THE MICROBIOLOGY OF SALTERN CRYSTALLIZER PONDS AND SALT QUALITY-A SEARCH FOR THE MISSING LINK
The size and quality of the salt crystals formed in solar saltern crystallizer ponds worldwide is highly variable. In some places large solid halite crystals precipitate that are easy to process and yield a high-quality product, while elsewhere crystals are soft, have a high content of entrapped mother liquor, and are difficult to harvest and to purify. As the raw material in all cases is seawater of nearly identical composition, it is often assumed that biological processes in the evaporation and/or crystallizer ponds may be responsible for the differences in salt quality. Presence of a community of red halophilic Archaea and the alga Dunaliella salina in the crystallizers is generally considered beneficial to the salt production process and excessive production of polysaccharide slime by the cyanobacterium Aphanothece halophytica in the intermediate-salinity evaporation ponds may lead to a deterioration of the quality of the salt precipitated in the crystallizers. In a search for the missing link between solar salt quality and saltern pond microbiology, I here provide a survey of organic chemicals known to be produced by different members of the microbial communities in saltern ponds. These compounds include compatible solutes (small organic molecules synthesized to provide osmotic stabilization of the cells) and different metabolites excreted by the cells in the course of their metabolism. Quantitative estimates of the concentrations of glycerol, glycine betaine, ectoine, dihydroxyacetone, acetate, lactate, and other potentially relevant organic compounds in the ponds show that expected concentrations are probably too low to significantly influence the crystal habit of the precipitating halite. Moreover, laboratory simulation experiments failed to show significant effects of any of these compounds (at concentrations up to 200 ppm) on halite crystallization. A new theory is here proposed, suggesting that proteins released during lysis of pond microorganisms, and especially of the red halophilic Archaea, may at least in part be responsible for the production of poor quality salt.
Halophilic Archaea Dunaliella glycerol protein
Aharon Oren
Department of Plant and Environmental Sciences, The Institute of Life Sciences, and the Moshe Shilo Minerva Center for Marine Biogeochemistry, The Hebrew University of Jerusalem,Jerusalem, Israel
国际会议
9th International Symposium on Salt(第九届世界盐业大会)
北京
英文
904-912
2009-09-05（万方平台首次上网日期，不代表论文的发表时间）