High pressure‐temperature bioreactor: Assays of thermostable hydrogenase with fiber optics

Miller, Jay F.; Nelson, Chad M.; Ludlow, Jan M.; Shah, Nilesh N.; Clark, Douglas S.

doi:10.1002/bit.260340715

Cited by 35 publications

(16 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For M. jannaschii, the upper temperature limit for methanogenesis was observed to increase from 94ЊC at 10 atm to 98ЊC at 250 atm (23). Hydrogenase, one of the key enzymes in the methanogenic pathway, has already been shown to be both more active and stable at high temperatures and pressures (11,22). From the EPR data on the model core lipid system, this upward shift of 4ЊC in the upper temperature limit over a span of 240 atm is consistent with and may be related to the observed shift in the membrane fluidity behavior, which is of similar magnitude.…”

Section: Discussionsupporting

confidence: 64%

Pressure effects on the composition and thermal behavior of lipids from the deep-sea thermophile Methanococcus jannaschii

Kaneshiro

Clark

1995

J Bacteriol

View full text Add to dashboard Cite

The deep-sea archaeon Methanococcus jannaschii was grown at 86؇C and under 8, 250, and 500 atm (1 atm ‫؍‬ 101.29 kPa) of hyperbaric pressure in a high-pressure, high-temperature bioreactor. The core lipid composition of cultures grown at 250 or 500 atm, as analyzed by supercritical fluid chromatography, exhibited an increased proportion of macrocyclic archaeol and corresponding reductions in archaeol and caldarchaeol compared with the 8-atm cultures. Thermal analysis of a model core-lipid system (23% archaeol, 37% macrocyclic archaeol, and 40% caldarchaeol) using differential scanning calorimetry revealed no well-defined phase transition in the temperature range of 20 to 120؇C. Complementary studies of spin-labeled samples under 10 and 500 atm in a special high-pressure, high-temperature electron paramagnetic resonance spectroscopy cell supported the differential scanning calorimetry phase transition data and established that pressure has a lipid-ordering effect over the full range of M. jannaschii's growth temperatures. Specifically, pressure shifted the temperature dependence of lipid fluidity by ca. 10؇C/500 atm.For archaea to flourish in the extreme environments that many inhabit, normal membrane structure and function must be preserved. Preservation of membrane function may derive partly from the unique physical structures of archaeal lipids, which differ greatly from those of their eubacterial counterparts (7,(16)(17)(18). In contrast to the straight or minimally branched, mostly unsaturated fatty acids of variable lengths found in eubacteria, archaeal apolar chains are based on saturated isopranoid alcohols typically containing 20 or 40 carbon atoms. These isopranyl chains are connected to a glycerol (or more rarely, a complex polyol) head group by ether bonds, not the fatty acid ester bonds common to eubacteria. Moreover, the stereochemistry of these ether lipids (D or sn-2,3) is opposite to that seen in eubacteria (L or sn-1,2). Some archaea also possess bilayer-spanning tetraether lipids, in which a pair of biphytanyl-based chains are linked to two glycerol moieties via ether bonds. In total, the structural differences are pronounced enough to raise the question of whether archaeal lipids respond differently to temperature and pressure than do eubacterial lipids, thus contributing to microbial viability under extreme conditions.Given that eubacterial thermophiles and barophiles do exist (6), the unique structural features of archaeal lipids are not necessarily required for retention of membrane structure and function at elevated temperatures and pressures. However, considering the abundance of archaea and relative scarcity of eubacteria at the outer regions of the pressure-temperature envelope at which life is known to exist, many archaea appear to possess an intrinsic capacity for thermophilic and barophilic behavior.To adapt to moderate fluctuations in temperature, virtually all eubacteria can maintain optimal membrane fluidity by modulating their lipid composition in a process termed homeoviscous ad...

show abstract

Section: Discussionsupporting

confidence: 64%

Pressure effects on the composition and thermal behavior of lipids from the deep-sea thermophile Methanococcus jannaschii

Kaneshiro

Clark

1995

J Bacteriol

View full text Add to dashboard Cite

show abstract

“…For the study and isolation of piezophilic microorganisms also sampling and incubation devices were developed and applied which allow processing of microbiological samples without depressurization (Kato, 2006 andreferences therein, Parkes et al, 2009). Two-phase batch incubation techniques with gas enrichment resulting from free-gas have also been described (Berberich et al, 2000;Boonyaratanakornkit et al, 2007;Kaneshiro and Clark, 1995;Knutson et al, 1999;Malahoff et al, 2002;Miller et al, 1989;Nelson et al, 1992). Further, several systems for high-pressure fed-batch or continuous incubation were designed and described (Houghton et al, 2007;Jannasch et al, 1996;Wirsen and Molyneaux, 1999).…”

Section: Discussionmentioning

confidence: 96%

High‐pressure systems for gas‐phase free continuous incubation of enriched marine microbial communities performing anaerobic oxidation of methane

Deusner

Meyer

Ferdelman

2009

Biotech & Bioengineering

View full text Add to dashboard Cite

Novel high-pressure biotechnical systems that were developed and applied for the study of anaerobic oxidation of methane (AOM) are described. The systems, referred to as high-pressure continuous incubation system (HP-CI system) and high-pressure manifold-incubation system (HP-MI system), allow for batch, fed-batch, and continuous gas-phase free incubation at high concentrations of dissolved methane and were designed to meet specific demands for studying environmental regulation and kinetics as well as for enriching microbial biomass in long-term incubation. Anoxic medium is saturated with methane in the first technical stage, and the saturated medium is supplied for biomass incubation in the second stage. Methane can be provided in continuous operation up to 20 MPa and the incubation systems can be operated during constant supply of gas-enriched medium at a hydrostatic pressure up to 45 MPa. To validate the suitability of the high-pressure systems, we present data from continuous and fed-batch incubation of highly active samples prepared from microbial mats from the Black Sea collected at a water depth of 213 m. In continuous operation in the HP-CI system initial methane-dependent sulfide production was enhanced 10- to 15-fold after increasing the methane partial pressure from near ambient pressure of 0.2 to 10.0 MPa at a hydrostatic pressure of 16.0 MPa in the incubation stage. With a hydraulic retention time of 14 h a stable effluent sulfide concentration was reached within less than 3 days and a continuing increase of the volumetric AOM rate from 1.2 to 1.7 mmol L(-1) day(-1) was observed over 14 days. In fed-batch incubation the AOM rate increased from 1.5 to 2.7 and 3.6 mmol L(-1) day(-1) when the concentration of aqueous methane was stepwise increased from 5 to 15 mmol L(-1) and 45 mmol L(-1). A methane partial pressure of 6 MPa and a hydrostatic pressure of 12 MPa in manifold fed-batch incubation in the HP-MI system yielded a sixfold increase in the volumetric AOM rate. Over subsequent incubation periods AOM rates increased from 0.6 to 1.2 mmol L(-1) day(-1) within 26 days of incubation. No inhibition of biomass activity was observed in all continuous and fed-batch incubation experiments. The organisms were able to tolerate high sulfide concentrations and extended starvation periods.

show abstract

“…Because many high-temperature environments are also high-pressure environments and because microorganisms cannot evade pressure and temperature, all the macromolecular cell components have to be adapted to high pressures. Thus, it is not surprising to find hyperthermophilic organisms that are also barophilic (such as Thermococcus barophilus [ Table 1]) and to find enzymes that are stabilized and activated by high pressures (e.g., M. jannaschii protease and hydrogenase) (129,247,248). The theory behind stabilization by pressure says that pressure favors the structure with the smallest volume.…”

Section: Extrinsic Parametersmentioning

confidence: 99%

Hyperthermophilic Enzymes: Sources, Uses, and Molecular Mechanisms for Thermostability

Vieille¹,

Zeikus

2001

Microbiol Mol Biol Rev

1,847

1,476

View full text Add to dashboard Cite

Enzymes synthesized by hyperthermophiles (bacteria and archaea with optimal growth temperatures of >80°C), also called hyperthermophilic enzymes, are typically thermostable (i.e., resistant to irreversible inactivation at high temperatures) and are optimally active at high temperatures. These enzymes share the same catalytic mechanisms with their mesophilic counterparts. When cloned and expressed in mesophilic hosts, hyperthermophilic enzymes usually retain their thermal properties, indicating that these properties are genetically encoded. Sequence alignments, amino acid content comparisons, crystal structure comparisons, and mutagenesis experiments indicate that hyperthermophilic enzymes are, indeed, very similar to their mesophilic homologues. No single mechanism is responsible for the remarkable stability of hyperthermophilic enzymes. Increased thermostability must be found, instead, in a small number of highly specific alterations that often do not obey any obvious traffic rules. After briefly discussing the diversity of hyperthermophilic organisms, this review concentrates on the remarkable thermostability of their enzymes. The biochemical and molecular properties of hyperthermophilic enzymes are described. Mechanisms responsible for protein inactivation are reviewed. The molecular mechanisms involved in protein thermostabilization are discussed, including ion pairs, hydrogen bonds, hydrophobic interactions, disulfide bridges, packing, decrease of the entropy of unfolding, and intersubunit interactions. Finally, current uses and potential applications of thermophilic and hyperthermophilic enzymes as research reagents and as catalysts for industrial processes are described

show abstract

High pressure‐temperature bioreactor: Assays of thermostable hydrogenase with fiber optics

Cited by 35 publications

References 21 publications

Pressure effects on the composition and thermal behavior of lipids from the deep-sea thermophile Methanococcus jannaschii

Pressure effects on the composition and thermal behavior of lipids from the deep-sea thermophile Methanococcus jannaschii

High‐pressure systems for gas‐phase free continuous incubation of enriched marine microbial communities performing anaerobic oxidation of methane

Hyperthermophilic Enzymes: Sources, Uses, and Molecular Mechanisms for Thermostability

Contact Info

Product

Resources

About