Effect of carbon and nitrogen sources on growth dynamics and exopolysaccharide production for the hyperthermophilic archaeonThermococcus litoralis and bacteriumThermotoga maritima

Rinker, Kristina D.; Kelly, Robert M.

doi:10.1002/1097-0290(20000905)69:5<537::aid-bit8>3.0.co;2-7

Cited by 94 publications

(89 citation statements)

References 53 publications

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“…Formation of alanine as a reduced end product in media containing abundant levels of pyruvate or sugars has been reported for several Thermococcales species, such as P. furiosus (17), T. kodakarensis (14), Thermococcus profundus (18), and Thermococcus litoralis (35), suggesting that alanine is a common metabolic end product in this order. Alanine formation is catalyzed by AlaAT through an amino transfer reaction from glutamate to pyruvate (17,18).…”

Section: Discussionmentioning

confidence: 80%

“…Our genetic results revealing decreased alanine production and increased NH 3 formation in Hyh-deficient T. kodakarensis cells indicate that significant amounts of NADPH for alanine synthesis are provided through the oxidation of H 2 . The metabolic link between H 2 uptake and alanine production seems to exist in other Thermococcales members, as cultivation of cells under an increased H 2 partial pressure resulted in increased alanine production in P. furiosus (3,17) and T. litoralis (35).…”

Section: Discussionmentioning

confidence: 99%

“…It has been reported in many cases that Thermococcales cells accumulate alanine as a reduced end product (14,17,18,35). Alanine is formed from pyruvate by alanine aminotransferase (AlaAT) using glutamate as an amino donor, which is reductively regenerated by glutamate dehydrogenase (GDH) using NADPH and NH 3 (17,18).…”

Section: Methodsmentioning

confidence: 99%

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Distinct Physiological Roles of the Three [NiFe]-Hydrogenase Orthologs in the Hyperthermophilic Archaeon Thermococcus kodakarensis

et al. 2011

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Hydrogenases catalyze the reversible oxidation of molecular hydrogen (H 2 ) and play a key role in the energy metabolism of microorganisms in anaerobic environments. The hyperthermophilic archaeon Thermococcus kodakarensis KOD1, which assimilates organic carbon coupled with the reduction of elemental sulfur (S 0 ) or H 2 generation, harbors three gene operons encoding [NiFe]-hydrogenase orthologs, namely, Hyh, Mbh, and Mbx. In order to elucidate their functions in vivo, a gene disruption mutant for each [NiFe]-hydrogenase ortholog was constructed. The Hyh-deficient mutant (PHY1) grew well under both H 2 S-and H 2 -evolving conditions. H 2 S generation in PHY1 was equivalent to that of the host strain, and H 2 generation was higher in PHY1, suggesting that Hyh functions in the direction of H 2 uptake in T. kodakarensis under these conditions. Analyses of culture metabolites suggested that significant amounts of NADPH produced by Hyh are used for alanine production through glutamate dehydrogenase and alanine aminotransferase. On the other hand, the Mbh-deficient mutant (MHD1) showed no growth under H 2 -evolving conditions. This fact, as well as the impaired H 2 generation activity in MHD1, indicated that Mbh is mainly responsible for H 2 evolution. The copresence of Hyh and Mbh raised the possibility of intraspecies H 2 transfer (i.e., H 2 evolved by Mbh is reoxidized by Hyh) in this archaeon. In contrast, the Mbx-deficient mutant (MXD1) showed a decreased growth rate only under H 2 S-evolving conditions and exhibited a lower H 2 S generation activity, indicating the involvement of Mbx in the S 0 reduction process. This study provides important genetic evidence for understanding the physiological roles of hydrogenase orthologs in the Thermococcales.

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Section: Discussionmentioning

confidence: 80%

Section: Discussionmentioning

confidence: 99%

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Distinct Physiological Roles of the Three [NiFe]-Hydrogenase Orthologs in the Hyperthermophilic Archaeon Thermococcus kodakarensis

et al. 2011

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“…In syntrophic coculture with a hydrogenotrophic methanogen, such as Methanococcus jannaschii (7), this inhibition is relieved and cell population density is enhanced through the interspecies transfer of hydrogen (26). In addition to the utilization of sugars as carbon and energy sources (8, 28), T. maritima also has been shown to produce exopolysaccharides (EPS) that serve as the basis for biofilms (35,36). In fact, when grown to high cell densities through coculture with the hyperthermophilic methanogen M. jannaschii, T. maritima produces EPS that leads to formation of stable cellular aggregates, which presumably facilitate interspecies H 2 transfer (26).…”

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confidence: 99%

The Thermotoga maritima Phenotype Is Impacted by Syntrophic Interaction with Methanococcus jannaschii in Hyperthermophilic Coculture

Johnson

Conners

Montero

et al. 2006

Appl Environ Microbiol

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Significant growth phase-dependent differences were noted in the transcriptome of the hyperthermophilic bacterium Thermotoga maritima when it was cocultured with the hyperthermophilic archaeon Methanococcus jannaschii. For the mid-log-to-early-stationary-phase transition of a T. maritima monoculture, 24 genes (1.3% of the genome) were differentially expressed twofold or more. In contrast, methanogenic coculture gave rise to 292 genes differentially expressed in T. maritima at this level (15.5% of the genome) for the same growth phase transition. Interspecies H 2 transfer resulted in three-to fivefold-higher T. maritima cell densities than in the monoculture, with concomitant formation of exopolysaccharide (EPS)-based cell aggregates. Differential expression of specific sigma factors and genes related to the ppGpp-dependent stringent response suggests involvement in the transition into stationary phase and aggregate formation. Cell aggregation was growth phase dependent, such that it was most prominent during mid-log phase and decayed as cells entered stationary phase. The reduction in cell aggregation was coincidental with down-regulation of genes encoding EPS-forming glycosyltranferases and up-regulation of genes encoding ␤-specific glycosyl hydrolases; the latter were presumably involved in hydrolysis of ␤-linked EPS to release cells from aggregates. Detachment of aggregates may facilitate colonization of new locations in natural environments where T. maritima coexists with other organisms. Taken together, these results demonstrate that syntrophic interactions can impact the transcriptome of heterotrophs in methanogenic coculture, and this factor should be considered in examining the microbial ecology in anaerobic environments.Despite the fact that microorganisms interact significantly within their ecological niche, this factor is usually not taken into account in the context of microbial physiology. One key limitation in this regard is that methodologies for examining the influence of one microbial species on another are typically based on either identification (e.g., 16S rRNA phylogeny [46]) or enumeration (e.g., fluorescent in situ hybridization [12]). Additional insights into functional outcomes of interspecies interactions are difficult to obtain. Yet such information is needed to relate pure culture cellular physiology to the beneficial and antagonistic elements present in microbial ecosystems.Syntrophic relationships between microorganisms with complementary growth physiologies are a key part of microbial ecosystems. One such example in certain anaerobic niches is the association between fermentative H 2 producers and methanogenic H 2 consumers, whereby the inhibitory H 2 formed as the by-product of sugar or peptide metabolism serves as an energy source for the generation of methane (26). This syntrophy can be found in niches ranging from the mammalian digestive tract (24) to anaerobic digesters used for domestic waste treatment (12). Molecular hydrogen is also a key chemical species in hydrothermal env...

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“…Thus, some of the variation between experimental conditions could reflect the variation within an experimental condition. This issue was examined by using a whole-genome cDNA microarray for Thermotoga maritima, an obligately anaerobic, hyperthermophilic, heterotrophic bacterium growing optimally at 80°C (2,4,8). Chemostat-based transcriptional response experiments with whole-genome cDNA microarrays were used to investigate sources of variance that contribute to the observed patterns of differential gene expression both within and between mechanical steady states (temperature and dilution rate) by using three common procedures used to assign differential gene expression.…”

mentioning

confidence: 99%

Genome-Wide Transcriptional Variation within and between Steady States for Continuous Growth of the HyperthermophileThermotoga Maritima

Shockley

Scott

Pysz

et al. 2005

Appl Environ Microbiol

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Maltose-limited, continuous growth of the hyperthermophile Thermotoga maritima at different temperatures and dilution rates (80°C/0.25 h ؊1 , 80°C/0.17 h ؊1 , and 85°C/0.25 h ؊1 ) showed that transcriptome-wide variation in gene expression within mechanical steady states was minimal compared to that between steady states, supporting the efficacy of chemostat-based approaches for functional genomics studies.Continuous culture can be an effective tool for determining global transcriptional patterns in functional genomics studies (5). It may also be useful for examining the fluctuation in gene expression that arises within a specific environmental context or growth condition. It is not clear yet whether biovariability in gene expression in unperturbed cells impacts the interpretation of transcriptional response to intended perturbations. Thus, some of the variation between experimental conditions could reflect the variation within an experimental condition. This issue was examined by using a whole-genome cDNA microarray for Thermotoga maritima, an obligately anaerobic, hyperthermophilic, heterotrophic bacterium growing optimally at 80°C (2, 4, 8). Chemostat-based transcriptional response experiments with whole-genome cDNA microarrays were used to investigate sources of variance that contribute to the observed patterns of differential gene expression both within and between mechanical steady states (temperature and dilution rate) by using three common procedures used to assign differential gene expression.Experimental overview. A full-genome Thermotoga maritima DNA microarray constructed from PCR products (3) was used to measure transcriptional variation during continuous cultivation (6). Three mechanical steady states chosen to reflect perturbations within the normal growth range of the organism were examined: 80°C at a dilution rate of 0.25 h Ϫ1 (six samples taken at 103.7, 109.3, 127.7, 133.4, 151.8, and 157.5 h [19.4 generations]), 85°C at a dilution rate of 0.25 h Ϫ1 (four samples taken at 435.4, 459.6, 483.4, and 501.7 h [23.9 generations]), and 80°C at a dilution rate of 0.17 h Ϫ1 (three samples taken at 879.0, 958.5, and 1,000.0 h [29.7 generations]) (Fig. 1). Isolation of total RNA, hybridizations and washes were performed as described previously (9). Slides were scanned with a Scanarray 4000 scanner (Perkin Elmer, Fremont, CA) and the raw intensity data were processed as described previously (1). The hybridization scheme was arranged according to a loop design strategy, which allows statistically efficient comparisons between samples (11).Simple "fold change" criteria and estimate-based probabilities. Differential gene expression calls based on simple fold change criteria were evaluated by pairwise t tests derived from least-squares mean estimates from log 2 -transformed raw signal intensity data and mixed model analyses (1). The log 2 -transformed analysis is referred to as "unnormalized" because systematic global variation remained confounded with growth state effects; important sources of variation wer...

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Effect of carbon and nitrogen sources on growth dynamics and exopolysaccharide production for the hyperthermophilic archaeonThermococcus litoralis and bacteriumThermotoga maritima

Cited by 94 publications

References 53 publications

Distinct Physiological Roles of the Three [NiFe]-Hydrogenase Orthologs in the Hyperthermophilic Archaeon Thermococcus kodakarensis

Distinct Physiological Roles of the Three [NiFe]-Hydrogenase Orthologs in the Hyperthermophilic Archaeon Thermococcus kodakarensis

The Thermotoga maritima Phenotype Is Impacted by Syntrophic Interaction with Methanococcus jannaschii in Hyperthermophilic Coculture

Genome-Wide Transcriptional Variation within and between Steady States for Continuous Growth of the HyperthermophileThermotoga Maritima

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