Temperature- and Salinity-Decoupled Overproduction of Hydroxyectoine by Chromohalobacter salexigens

Rodríguez-Moya, Javier; Argandoña, Montserrat; Iglesias‐Guerra, Fernando; Nieto, Joaquı́n J.; Vargas, Carmen Regla

doi:10.1128/aem.02774-12

Cited by 27 publications

(25 citation statements)

References 30 publications

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“…AAD12 produced 525 mol hydroxyectoine/g dry cell mass. This amount is pretty much comparable to the hydroxyectoine yield by the engineered C. salexigens [29]. Hydroxyectoine yield can further be enhanced by engineering the strain [29,30].…”

Section: Discussionsupporting

confidence: 52%

“…In contrast to our findings, Saum and Müller [12] reported that the moderately halophilic Halobacillus halophilus changed its osmolyte accumulation strategy through exchanging proline by ectoine in the transition from exponential to stationary phase. Another moderate halophile, C. salexigens, accumulated maximum ectoine at 37°C with 17.4% NaCl and maximum hydroxyectoine at 45°C with 14.5% NaCl [29]. Maximum hydroxyectoine accumulation was achieved with 15% NaCl by both C. salexigens and Halomonas sp.…”

Section: Discussionmentioning

confidence: 77%

“…AAD12. Hydroxyectoine yield in the engineered C. salexigens was as high as 883 mol/g bacterial dry matter with 4.35% NaCl at 37°C [29].…”

Section: Discussionmentioning

confidence: 94%

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Moderately Halophilic Bacterium Halomonas sp. AAD12: A Promising Candidate as a Hydroxyectoine Producer

B¹,

A²,

G³

2015

J Microb Biochem Technol

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Properties of osmolytes that help protect biological molecules from stress and preserve their functions impose significant importance to finding new organisms with different osmolyte accumulation strategies. To this end, the moderately halophilic Halomonas sp. AAD12 has been characterized for its adaptation to stress conditions with particular emphasis on its osmolyte accumulation strategy. The effect of temperature, salinity, aeration and organic components on the accumulation of osmoprotectants and synthesis of fatty acids were examined in M63 minimal medium. Ectoine, proline and hydroxyectoine were the major osmolytes and palmitic acid (16:0), palmitoleic acid (16:1), and oleic acid (18:1) were the major fatty acids. Overall, ectoine yield was the highest among the three osmolytes at all salt concentrations and temperatures investigated. However, high salinity reduced ectoine yield with a concomitant increase in hydroxyectoine yield. The yield of hydroxyectoine as high as 525 mol/g dry cell mass at 37°C suggested that this microorganism could be a promising candidate as a hydroxyectoine producer.

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Section: Discussionsupporting

confidence: 52%

Section: Discussionmentioning

confidence: 77%

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Moderately Halophilic Bacterium Halomonas sp. AAD12: A Promising Candidate as a Hydroxyectoine Producer

B¹,

A²,

G³

2015

J Microb Biochem Technol

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“…Ectoine excreting and ectoine overproducing mutants of H. elongata are used for the industrial production of ectoine (Kunte et al ., ). Chromohalobacter salexigens has been suggested as an alternative ectoines producer (Fallet et al ., ; Rodríguez‐Moya et al ., ). Thus, the elucidation of C. salexigens mechanisms controlling the synthesis of ectoines is important to design novel metabolic engineering strategies for generating improved strains.…”

Section: Introductionmentioning

confidence: 97%

Contribution of RpoS to metabolic efficiency and ectoines synthesis during the osmo‐ and heat‐stress response in the halophilic bacterium Chromohalobacter salexigens

Salvador

Argandoña

Pastor

et al. 2015

Environ Microbiol Rep

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Chromohalobacter salexigens is a halophilic γ-proteobacterium that responds to osmotic and heat stresses by accumulating ectoine and hydroxyectoine respectively. Evolution has optimized its metabolism to support high production of ectoines. We analysed the effect of an rpoS mutation in C. salexigens metabolism and ectoines synthesis. In long-term adapted cells, the rpoS strain was osmosensitive but not thermosensitive and showed unaltered ectoines content, suggesting that RpoS regulates ectoine(s)-independent osmoadaptive mechanisms. RpoS is involved in the regulation of C. salexigens metabolic adaptation to stress, as early steps of glucose oxidation through the Entner-Doudoroff pathway were deregulated in the rpoS mutant, leading to improved metabolic efficiency at low salinity. Moreover, a reduced pyruvate (but not acetate) overflow was displayed by the rpoS strain at low salt, probably linked to a slowdown in gluconate production and/or subsequent metabolism. Interestingly, RpoS does not seem to be the main regulator triggering the immediate transcriptional response of ectoine synthesis to osmotic or thermal upshifts. However, it contributed to the expression of the ect genes in cells previously adapted to low or high salinity.

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“…With respect to the latter approaches, ectoine/hydroxyectoine biosynthetic genes have been cloned into plasmids under the transcriptional control of either natural ect or synthetic promoters and transferred to Escherichia coli or Corynebacterium glutamicum host strains (59)(60)(61)(62) or integrated into the chromosomes of biotechnological workhorses such as C. glutamicum (63) or the methylotrophic yeast Hansenula polymorpha (64). In some cases, advanced pathway engineering approaches were also used to enhance the synthetic production of ectoines in homologous and heterologous hosts (62,63,65,66).…”

mentioning

confidence: 99%

Tinkering with Osmotically Controlled Transcription Allows Enhanced Production and Excretion of Ectoine and Hydroxyectoine from a Microbial Cell Factory

Czech

Poehl

Hub

et al. 2018

Appl Environ Microbiol

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Ectoine and hydroxyectoine are widely synthesized by members of the and a few as potent osmostress protectants. We have studied the salient features of the osmostress-responsive promoter directing the transcription of the ectoine/hydroxyectoine biosynthetic gene cluster from the plant-roots-associated bacterium by transferring it into, an enterobacterium that does not produce ectoines naturally. Using reporter fusions, we found that the heterologous promoter reacted with exquisite sensitivity in its transcriptional profile to graded increases in sustained high salinity, responded to a true osmotic signal, and required the build-up of an osmotically effective gradient across the cytoplasmic membrane for its induction. The involvement of the -10, -35, and spacer regions of the Sigma-70 type promoter in setting promoter strength and response to osmotic stress was assessed through site-directed mutagenesis. Moderate changes in the promoter sequence that increase its resemblance to house-keeping Sigma-70-type promoters of afforded substantially enhanced expression, both in absence and in the presence of osmotic stress. Building on this set of promoter mutants, we engineered an chassis strain for the heterologous production of ectoines. This synthetic cell factory lacks the genes for the osmostress-responsive synthesis of trehalose and the compatible solute importers ProP and ProU and it continuously excretes ectoines into the growth medium. By combining appropriate host strains and different plasmid variants, excretion of ectoine, hydroxyectoine, or a mixture of both compounds was achieved under mild osmotic stress conditions.Ectoines are compatible solutes, organics osmolytes that are used by microorganisms to fend off the negative consequences of high environmental osmolarity on cellular physiology. An understanding of the salient features of osmostress-responsive promoters directing the expression of the ectoine/hydroxyectoine biosynthetic gene clusters is lacking. We exploited the promoter from an ectoine/hydroxyectoine-producing soil bacterium for such a study by transferring it into a surrogate bacterial host. Despite the fact that does not synthesize ectoines naturally, the promoter retained its exquisitely sensitive osmotic control, indicating that osmoregulation of transcription is an inherent feature of the promoter and its flanking sequences. These sequences were narrowed to a 116 bp DNA fragment. Ectoines have interesting commercial applications. Building on data from a site-directed mutagenesis study of the promoter, we designed a synthetic cell factory that secretes ectoine, hydroxyectoine, or a mixture of both compounds, into the growth medium.

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Temperature- and Salinity-Decoupled Overproduction of Hydroxyectoine by Chromohalobacter salexigens

Cited by 27 publications

References 30 publications

Moderately Halophilic Bacterium Halomonas sp. AAD12: A Promising Candidate as a Hydroxyectoine Producer

Moderately Halophilic Bacterium Halomonas sp. AAD12: A Promising Candidate as a Hydroxyectoine Producer

Contribution of RpoS to metabolic efficiency and ectoines synthesis during the osmo‐ and heat‐stress response in the halophilic bacterium Chromohalobacter salexigens

Tinkering with Osmotically Controlled Transcription Allows Enhanced Production and Excretion of Ectoine and Hydroxyectoine from a Microbial Cell Factory

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