Halophilic Microorganisms and their Environments

Oren, Aharon

doi:10.1007/0-306-48053-0

Cited by 401 publications

(321 citation statements)

References 756 publications

(1,241 reference statements)

Supporting

Mentioning

294

Contrasting

Unclassified

Order By: Relevance

“…Therefore, the methylaspartate cycle is well adapted for the assimilation of acetyl-CoA produced from the internal carbon storage during carbon starvation (Figure 1). This feature is especially important for haloarchaea living under conditions of frequent starvation periods and intermittently occurring blooms when the biomass (and storage compounds) are produced (Oren, 2002). Therefore, we hypothesize that the methylaspartate cycle is a preferential strategy for haloarchaea that should rely on assimilation of storage compounds in their natural habitats.…”

Section: Discussionmentioning

confidence: 97%

“…Although accumulation of high concentrations of KCl is the main strategy used by haloarchaea to balance their cytoplasm osmotically with their medium (Oren, 2002), high intracellular glutamate concentration may be advantageous for a halophilic organism. Indeed, glutamate is a well-known osmolyte used by many halophiles (Oren, 2002) and is the precursor for the intracellular antioxidant γ-glutamylcystein used by haloarchaea (Malki et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

“…Halophilic archaea of the class Halobacteria (haloarchaea) live in concentrated salt solutions and belong to the most important microbial habitants of saturated brine environments such as salt lakes or salterns (Oren, 2002). Their environment is photic, (micro)oxic and rich in organic nutrients, which determines them as aerobic (photo)organoheterotrophs.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The methylaspartate cycle in haloarchaea and its possible role in carbon metabolism

et al. 2015

View full text Add to dashboard Cite

Haloarchaea (class Halobacteria) live in extremely halophilic conditions and evolved many unique metabolic features, which help them to adapt to their environment. The methylaspartate cycle, an anaplerotic acetate assimilation pathway recently proposed for Haloarcula marismortui, is one of these special adaptations. In this cycle, acetyl-CoA is oxidized to glyoxylate via methylaspartate as a characteristic intermediate. The following glyoxylate condensation with another molecule of acetylCoA yields malate, a starting substrate for anabolism. The proposal of the functioning of the cycle was based mainly on in vitro data, leaving several open questions concerning the enzymology involved and the occurrence of the cycle in halophilic archaea. Using gene deletion mutants of H. hispanica, enzyme assays and metabolite analysis, we now close these gaps by unambiguous identification of the genes encoding all characteristic enzymes of the cycle. Based on these results, we were able to perform a solid study of the distribution of the methylaspartate cycle and the alternative acetate assimilation strategy, the glyoxylate cycle, among haloarchaea. We found that both of these cycles are evenly distributed in haloarchaea. Interestingly, 83% of the species using the methylaspartate cycle possess also the genes for polyhydroxyalkanoate biosynthesis, whereas only 34% of the species with the glyoxylate cycle are capable to synthesize this storage compound. This finding suggests that the methylaspartate cycle is shaped for polyhydroxyalkanoate utilization during carbon starvation, whereas the glyoxylate cycle is probably adapted for growth on substrates metabolized via acetyl-CoA.

show abstract

Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The methylaspartate cycle in haloarchaea and its possible role in carbon metabolism

et al. 2015

View full text Add to dashboard Cite

show abstract

“…(Ben-Amotz & Avron, 1973) and Asteromonas gracilis (Oren, 2002), and in fungi and yeasts, such as Aspergillus niger (Witteveen & Visser, 1995), S. cerevisiae (Blomberg & Adler, 1992), Debaryomyces hansenii (Adler et al, 1985), Zygosaccharomyces rouxii (Kayingo et al, 2001) and Yarrowia lipolytica (Andreishcheva et al, 1999). Besides glycerol, other polyols such as erythritol, arabitol and mannitol are also recognized to be compatible solutes in fungi.…”

Section: Discussionmentioning

confidence: 99%

Osmotic adaptation of the halophilic fungus Hortaea werneckii: role of osmolytes and melanization

et al. 2007

View full text Add to dashboard Cite

This study was intended to determine the osmoadaptation strategy of Hortaea werneckii, an extremely salt-tolerant melanized ascomycetous fungus that can grow at 0-5.1 M NaCl. It has been shown previously that glycerol is the major compatible solute in actively growing H. werneckii. This study showed that the exponentially growing cells also contained erythritol, arabitol and mannitol at optimal growth salinities, but only glycerol and erythritol at maximal salinities. The latter two were both demonstrated to be major compatible solutes in H. werneckii, as their decrease correlated with the severity of hypoosmotic shock. Besides higher amounts of erythritol and lower amounts of glycerol, stationary-phase cells also contained mycosporineglutaminol-glucoside, which might act as a complementary compatible solute. H. werneckii is constitutively melanized under various salinity conditions. Ultrastructural study showed localization of melanin in the outer parts of the cell wall as a distinct layer at optimal salinity (0.86 M NaCl), whereas cell-wall melanization diminished at higher salinities. The role of melanized cell wall in the effective retention of glycerol is already known, and was also demonstrated in H. werneckii by lower retention of glycerol in cells with blocked melanization compared to melanized cells. However, these non-melanized cells compensated for the lower amounts of glycerol with higher amounts of erythritol and arabitol. We hypothesize that H. werneckii melanization is effective in reducing the permeability of its cell wall to its major compatible solute glycerol, which might be one of the features that helps it tolerate a wider range of salt concentrations than most organisms.

show abstract

“…Many truly halophilic bacteria accommodate glycine betaine as organic compatible solutes (eg., Ectothiorhodospira sp., Halorhodospira sp. ), an osmolyte also found in the alkaliphilic, halophilic or extremely halotolerant SOB of the genera Thioalkalivibrio and Thiohalomonas (Banciu et al 2005;Galinski 1995;Oren 2002;Sorokin et al 2007). Figure 8 attempts to represent a salt/pH ecological niche characteristic for strain ALCO 1 in comparison with several halo(alkali)philic SOB.…”

Section: Discussionmentioning

confidence: 99%

Influence of salts and pH on growth and activity of a novel facultatively alkaliphilic, extremely salt-tolerant, obligately chemolithoautotrophic sufur-oxidizing Gammaproteobacterium Thioalkalibacter halophilus gen. nov., sp. nov. from South-Western Siberian soda lakes

et al. 2008

View full text Add to dashboard Cite

Halophilic Microorganisms and their Environments

Cited by 401 publications

References 756 publications

The methylaspartate cycle in haloarchaea and its possible role in carbon metabolism

The methylaspartate cycle in haloarchaea and its possible role in carbon metabolism

Osmotic adaptation of the halophilic fungus Hortaea werneckii: role of osmolytes and melanization

Influence of salts and pH on growth and activity of a novel facultatively alkaliphilic, extremely salt-tolerant, obligately chemolithoautotrophic sufur-oxidizing Gammaproteobacterium Thioalkalibacter halophilus gen. nov., sp. nov. from South-Western Siberian soda lakes

Contact Info

Product

Resources

About