On the gas vacuoles of the halobacteria

Summary The cells of Halobacterium sp., strain 5, contain a large number of highly refractile bodies of the type which Petter (1932) suggested were gas-filled vacuoles. The present studies support Petter's contention, but the evidence for the exact chemical nature of the vacuole content is still indirect. It is not carbon dioxide or oxygen, but might possibly be nitrogen. Strain 5 loses spontaneously and with a high frequency the ability to make the vacuoles.When vacuolated cells are subjected to pressure, the vacuoles disappear, but can recover upon aeration. Oxygen and the organic constituents of the growth medium stimulate the recovery, whereas 2.4-dinitrophenol inhibits it. A procedure is described for the isolation of the vacuoles. The vacuoles are bounded by a membrane which reveals itself in electron micrographs of thin sections as a 1-layered structure about 30 Å thick.Dedicated to Prof. C. B. van Niel on the occasion of his 70th birthday.     

A microbiological study of an underground gas storage in the process of gas extraction

The numbers of microorganisms belonging to ecologically significant groups and the rates of terminal microbial processes of sulfate reduction and methanogenesis were determined in the liquid phase of an underground gas storage (UGS) in the period of gas extraction. The total number of microorganisms in water samples from the operation and injection wells reached 2.1 x 10(6) cells/ml. Aerobic organotrophs (including hydrocarbon- and oil-oxidizing ones) and various anaerobic microorganisms (fermenting bacteria, methanogens, acetogens, sulfate-, nitrate-, and iron-reducing bacteria) were constituent parts of the community. The radioisotopic method showed that, in all the UGS units, the terminal stages of organic matter decomposition included sulfate reduction and methanogenesis, with the maximal rate of these processes recorded in the aqueous phase of above-ground technological equipment which the gas enters from the operation wells. A comparative analysis by these parameters of different anaerobic ecotopes, including natural hydrocarbon fields, allows us to assess the rate of these processes in the UGS as high throughout the annual cycle of its operation. The data obtained indicate the existence in the UGS of a bacterial community that is unique in its diversity and metabolic capacities and able to make a certain contribution to the geochemistry of organic and inorganic compounds in the natural and technogenic ecosystem of the UGS and thus influence the industrial gas composition.     

A microbiological study of an underground gas storage in the process of gas extraction

The numbers of microorganisms belonging to ecologically significant groups and the rates of terminal microbial processes of sulfate reduction and methanogenesis were determined in the liquid phase of an underground gas storage (UGS) in the period of gas extraction. The total number of microorganisms in water samples from the operation and injection wells reached 2.1 × 10⁶ cells/ml. Aerobic organotrophs (including hydrocarbon-and oil-oxidizing ones) and various anaerobic microorganisms (fermenting bacteria, methanogens, acetogens, sulfate-, nitrate-, and iron-reducing bacteria) were constituent parts of the community. The radioisotopic method showed that, in all the UGS units, the terminal stages of organic matter decomposition included sulfate reduction and methanogenesis, with the maximal rate of these processes recorded in the aqueous phase of above-ground technological equipment which the gas enters from the operation wells. A comparative analysis by these parameters of different anaerobic ecotopes, including natural hydrocarbon fields, allows us to assess the rate of these processes in the UGS as high throughout the annual cycle of its operation. The data obtained indicate the existence in the UGS of a bacterial community that is unique in its diversity and metabolic capacities and able to make a certain contribution to the geochemistry of organic and inorganic compounds in the natural and technogenic ecosystem of the UGS and thus influence the industrial gas composition.     

A microbiological study of an underground gas storage in the process of gas injection

The liquid phase of different units of an underground gas storage (UGS) in the period of gas injection was studied with respect to its hydrochemical composition and characterized microbiologically. The presence of viable aerobic and anaerobic bacteria was revealed in the UGS stratal and associated waters. An important source of microorganisms and biogenic elements in the ecosystem studied is water and various technogenic admixtures contained in trace amounts in the gas entering from the gas main in the period of gas injection into the storage. Owing to this fact, the bacterial functional diversity, number, and activity are maximal in the system of gas treatment and purification and considerably lower in the observation well zone. At the terminal stages, the anaerobic transformation of organic matter in the UGS aqueous media occurs via sulfate reduction and methanogenesis; exceptionally high rates of these processes (up to 4.9 x 10(5) ng S(2-)l(-1) day(-1) and 2.8 x 10(6) nl CH4 l(-1) day(-1), respectively) were recorded for above-ground technological equipment.     

A microbiological study of an underground gas storage in the process of gas injection

The liquid phase of different units of an underground gas storage (UGS) in the period of gas injection was studied with respect to its hydrochemical composition and characterized microbiologically. The presence of viable aerobic and anaerobic bacteria was revealed in the UGS stratal and associated waters. An important source of microorganisms and biogenic elements in the ecosystem studied is water and various technogenic admixtures contained in trace amounts in the gas entering from the gas main in the period of gas injection into the storage. Owing to this fact, the bacterial functional diversity, number, and activity are maximal in the system of gas treatment and purification and considerably lower in the observation well zone. At the terminal stages, the anaerobic transformation of organic matter in the UGS aqueous media occurs via sulfate reduction and methanogenesis; exceptionally high rates of these processes (up to 4.9 × 10⁵ ng S^2? l^?1 day^?1 and 2.8 × 10⁶ nl CH₄ l^?1 day^?1, respectively) were recorded for above-ground technological equipment.     

Influence of relative gas humidity on the inactivation efficiency of a low temperature gas plasma

Aims:  To investigate the effect of relative gas humidity on the inactivation efficiency of a cascaded dielectric barrier discharge (CDBD) in air against Aspergillus niger and Bacillus subtilis spores on PET foils.
Methods and Results:  The inactivation kinetics as a function of treatment time were determined using synthetic air with different relative humidity as the process gas. Spores of A. niger and B. subtilis respectively were evenly sprayed on PET foils for use as bioindicators. In the case of A. niger, increased spore mortality was found at a high relative gas humidity of 70% (approx. 2 log₁₀). This effect was more evident at prolonged treatment times. In contrast, B. subtilis showed slightly poorer inactivation at high gas humidity.
Conclusions:  Water molecules in the process gas significantly affect the inactivation efficiency of CDBD in air.
Significance and Impact of the Study:  Modifying simple process parameters such as the relative gas humidity can be used to optimize plasma treatment to improve inactivation of resistant micro-organisms such as conidiospores of A. niger .     

Estimating the greenhouse gas footprint of Knorr

Purpose  

Greenhouse gas (GHG) emissions have been identified as one of Unilever’s priority environmental impact themes: this assessment was therefore conducted to help the Knorr brand measure and understand the GHG emissions related to its product portfolio, identify opportunities to manage GHG emissions in the Unilever-owned operations (manufacture) and influence managed reductions elsewhere in the Knorr product lifecycles, and assess the impact of the brand’s innovation and portfolio strategies on its GHG footprint.     

A gas meter for low rates of gas flow: Application to the methane fermentation

Summary A device for measuring low rates of gas flow is described and an example of application to the methane fermentation is reported. Its principle is based on the total counts of impulsions corresponding to the successive filling and emptying operations of a calibrated flask. This gas meter can be used for flow rates ranging from milliliters- to liters per day.     

Rupture of the cell envelope by induced intracellular gas phase expansion in gas vacuolate bacteria.

Using a new approach, we estimated the physical strength of the cell envelopes of three species of gram-negative, gas vacuolate bacteria (Microcyclus aquaticus, Prosthecomicrobium pneumaticum, and Meniscus glaucopis). Populations of cells were slowly (0.5 to 2.9 h) saturated with argon, nitrogen, or helium to final pressures up to 100 atm (10, 132 kPa). The gas phases of the vesicles remained intact and, upon rapid (1 to 2 s) decompression to atmospheric pressure, expanded and ruptured the cells; loss of colony-forming units was used as an index of rupture. Because the cell envelope is the cellular component most likely to resist the expanding intracellular gas phase, its strength can be estimated from the minimum gas pressures that produce rupture. The viable counts indicated that these minimum pressures were between 25 and 50 atm; the majority of the cell envelopes were ruptured at pressures between 50 and 100 atm. Cells in which the gas vesicles were collapsed and the gas phases were effectively dissolved by rapid compression tolerated decompression from much higher gas saturations. Cells that do not normally possess gas vesicles (Escherichia coli) or that had been prevented from forming them by addition of L-lysine to the medium (M. aquaticus) were not harmed by decompression from gas saturation pressures up to 300 atm.     

Distal projection of insufflated gas during tracheal gas insufflation.

Tracheal gas insufflation (TGI) flushes expired gas from the ventilator circuitry and central airways, augmenting CO2 clearance. Whereas a significant portion of this washout effect may occur distal to the injection orifice, the penetration and mixing behavior of TGI gas has not been studied experimentally. We examined the behavior of 100% oxygen TGI injected at set flow rates of 1-20 l/min into a simulated trachea consisting of a smooth-walled, 14-mm-diameter tube. Models incorporating a separate coaxial TGI injector, a rough-walled trachea, and a bifurcated trachea were also studied. One-hundred percent nitrogen, representing expiratory flow, passed in the direction opposite to TGI at set flow rates of 1-25 l/min. Oxygen concentration within the "trachea" was mapped as a function of axial and radial position. Three consistent findings were observed: 1) mixing of expiratory and TGI gases occurred close to the TGI orifice; 2) the oxygenated domain extended several centimeters beyond the endotracheal tube, even at high-expiratory flows, but had a defined distal limit; and 3) more distally from the site of gas injection, the TGI gas tended to propagate along the tracheal wall, rather than as a central projection. We conclude that forward-directed TGI penetrates a substantial distance into the central airways, extending the compartment susceptible to CO2 washout.     

The sequence of the major gas vesicle protein,GvpA, influences the width and strength of halobacterial gas vesicles

Transformation experiments with Haloferax volcanii show that the amino acid sequence of the gas vesicle protein GvpA influences the morphology and strength of gas vesicles produced by halophilic archaea. A modified expression vector containing p-gvpA was used to complement a Vac(-) strain of Hfx. volcanii that harboured the entire p-vac region (from Halobacterium salinarum PHH1) except for p-gvpA. Replacement of p-gvpA with mc-gvpA (from Haloferax mediterranei) led to the synthesis of gas vesicles that were narrower and stronger. Other gene replacements (using c-gvpA from Hbt. salinarum or mutated p-gvpA sequences) led to a significant but smaller increase in gas vesicle strength, and less marked effects on gas vesicle morphology.