Fructans of the saline world

Abstract

Saline and hypersaline environments make up the largest ecosystem on earth and the organisms living in such water-restricted environments have developed unique ways to cope with high salinity. As such these organisms not only carry significant industrial potential in a world where freshwater supplies are rapidly diminishing, but they also shed light upon the origins and extremes of life. One largely overlooked and potentially important feature of many salt-loving organisms is their ability to produce fructans, fructose polymers widely found in various mesophilic Eubacteria and plants, with potential functions as storage carbohydrates, aiding stress tolerance, and acting as virulence factors or signaling molecules. Intriguingly, within the whole archaeal domain of life, Archaea possessing putative fructan biosynthetic enzymes were found to belong to the extremely halophilic class of Halobacteria only, indicating a strong, yet unexplored link between the fructan syndrome and salinity. In fact, this link may indeed lead to novel strategies in fighting the global salinization problem. Hence this review explores the unknown world of fructanogenic salt-loving organisms, where water scarcity is the main stress factor for life. Within this scope, prokaryotes and plants of the saline world are discussed in detail, with special emphasis on their salt adaptation mechanisms, the potential roles of fructans and fructosyltransferase enzymes in adaptation and survival as well as future aspects for all fructanogenic salt-loving domains of life.

Plant Growth-Promoting Bacteria: Biological Tools for the Mitigation of Salinity Stress in Plants

“…The world is saline; this is evident from the fact that, on average, the oceanic waters have a salinity of about 3.5%, which constitutes about 96.5% (roughly 1.3 billion km 3 ) of the Earth’s water ( Kırtel et al, 2018 ). Apart from this, roughly 12.87 million km 3 of saline water is groundwater, and 85400 km 3 of saline water is found in lakes ( Eakins and Sharman, 2010 ; Kırtel et al, 2018 ). The acceptable limit of electrical conductivity (EC) causing no damage to crops is <0.7 dS/m, while EC over 3.0 dS/m severely affects the crop yield ( Ayers and Westcot, 1985 ).…”

Discovery of fructans in Archaea

“…As discussed in Kırtel et al (2018a), putative GH-J clan genes are present in only extremely halophilic class of Halobacteria within all Archaeal lineages. Fructanogenic Archaea show a wide distribution within all three orders of the Halobacteria class (Fig.…”

“…The other strains were purchased from DSMZ GmbH (Germany), namely Halomicrobium mukohataei DSM 12286 isolated from Salinas Grandes, Argentina (Ihara, Watanabe, & Tamura, 1997;Oren, Elevi, Watanabe, Ihara, & Corcelli, 2002), Haloferax prahovense DSM 18310 isolated from Telega Lake, Romania (Enache, Itoh, Kamekura, Teodosiu, & Dumitru, 2007), and Natronococcus jeotgali DSM 18795 isolated from fermented shrimp in Korea (Roh et al, 2007). These particular strains were selected because of the presence of putative GH68 family genes in their genomes (Kırtel et al, 2018a).…”

The Recent Progress in Modification of Polymeric Membranes Using Organic Macromolecules for Water Treatment

“…These anthropogenic activities introduce various organic and inorganic contaminants into the water systems [1,3]. Worsening the issue, only 2.5% of the water on Earth is safe for consumption and most of this freshwater is locked in the form of glaciers, icecaps and underground water [4]. Based on the current circumstances, it is predicted about 3.9 billion people will live in regions under conditions of severe water scarcity by 2030 [5].…”