Theoretical Analysis of Continuous Culture Systems

Fencl, Z.

doi:10.1016/b978-1-4832-3311-6.50007-3

Cited by 54 publications

(9 citation statements)

References 14 publications

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“…(1) should be modified to take into ac-count the net reduction in cell production (weight basis) produced by endogenous respiration occurring as the end of the substrate-limiting phase is approached,…”

Section: The Process Model; Kineticsmentioning

confidence: 99%

Input and volume distributions for continuous cultures

Grieves

Kao

1968

Biotech & Bioengineering

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SummaryA4n analysis is presented of the effects on substrate utilization and cell growth of varying the volume distribution of and the input distribution to a model continuous-culture unit consisting of three stirred tanks. The model is used to establish the best volume and input distributions and to indicate the effects of mixing imperfections. The Michaelis-Menten rate expression is utilized, including an endogenous respiration term, and results are presented on unique triaxial charts. Of the distributions considered, maximum substrate utilization is achieved with 607c of the total volume in the first stage, 207, in the second stage, and ZOC?, in the third stage and with all of the input to the first stage. At a constant fractional input to the third stage, variation in the ratio of inputs to the first and second stages has virtually no effect, except in the case that a critical dilution is exceeded. A t a constant input ratio to the first two stages, an increase in the fractional input to the third stage always decreases efficiency. Three stages, regardless of relative size, are always better than one. Except for endogenous respiration effects, cell growth parallels substrate utilization.

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Section: The Process Model; Kineticsmentioning

confidence: 99%

Input and volume distributions for continuous cultures

Grieves

Kao

1968

Biotech & Bioengineering

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“…Throughout the continuous culture of M. piezophila, microbial growth was adjusting to the different pressures and dilution rates. The relationship between the dilution rate and the specific growth rate dictates the sustainability of the microbial population during continuous culture (23,24). For conditions under which D was greater than , such as those exemplified at 0.1 (47 to 55 h) and 10 (81 to 103 h) MPa, cell washout suppressed biomass accumulation (Fig.…”

Section: Growth Of M Piezophila During Continuous Culture Under Varymentioning

confidence: 99%

“…The estimated specific growth rates () under continuous medium flow were constrained by both pressure and dilution rate. The dilution rate (D), defined as the ratio of the flow rate to the volume of the bioreactor (23,24), ranged from 1.043 to 0.013 h Ϫ1 (see Table S1 in the supplemental material).The magnetic agitator operated at 70 to 100 rpm throughout the course of the experiment. Continuous culture of M. piezophila was conducted without interruption for 352 h (see Table S1).…”

Section: Growth Of M Piezophila During Continuous Culture Under Varymentioning

confidence: 99%

A Continuous Culture System for Assessing Microbial Activities in the Piezosphere

Foustoukos

Pérez‐Rodríguez

2015

Appl Environ Microbiol

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Continuous culture under elevated pressures is an important technique for expanding the exploration of microbial growth and survival in extreme environments associated with the deep biosphere. Here we present a benchtop stirred continuous culture bioreactor capable of withstanding temperatures ranging from 25 to 120°C and pressures as high as 69 MPa. The system is configured to allow the employment of media enriched in dissolved gases, under oxic or anoxic conditions, while permitting periodic sampling of the incubated organisms with minimal physical/chemical disturbance inside the reactor. In a pilot experiment, the fermentative growth of the thermopiezophilic bacterium Marinitoga piezophila was investigated continuously for 382 h at 65°C and at pressures ranging from 0.1 to 40 MPa while the medium flow rate was varied from 2 to 0.025 ml/min. The enhanced growth observed at 30 and 40 MPa and 0.025 ml/min supports the pressure preferences of M. piezophila when grown fermentatively. This assay successfully demonstrates the capabilities of the bioreactor for continuous culturing at a variety of dilution rates, pressures, and temperatures. We anticipate that this technology will accelerate our understanding of the physiological and metabolic status of microorganisms under temperature, pressure, and energy regimes resembling those of the Earth's piezosphere.T he recent trend toward global postgenomic assessments of microbial processes has reestablished the relevance of chemostat cultures for studying physiology and function in association with genetic patterns at the whole-organism level (1). This trend will require the inclusion of high-pressure microbial processes, because a large fraction of the Bacteria and Archaea is contained in the world's oceans at an average pressure of 38 MPa (2). This piezosphere is variable with depth in terms of thermal and nutrient conditions, extending from the cold/oligotrophic deep ocean to warm, nutrient-rich hydrothermal vents along mid-ocean ridges and subseafloor/continental environments with highly variable sources of energy and thermal gradients (3-5). The broad range of pressure-adapted phenotypes in biology (i.e., from piezosensitivity to piezotolerance and piezophily) makes in situ microbial activities hard to predict (6-9). At the moment, it is not known how these phenotypes may be linked to different energetic conditions, from bare support of maintenance processes at minimal growth rates to competition with kinetically favorable abiotic reactions (10, 11). Limited observations have already generated some relationships between phylogeny, function, and piezophily in several heterotrophs from the Alphaproteobacteria (4, 12). However, the few known links between pressure responses, metabolism, and phylogeny are unable to provide general concepts in high-pressure microbial ecology.Here we present a novel high-pressure bioreactor developed to facilitate the classical rate/substrate-controlled continuous culture of microorganisms while also providing the capacity for pressure an...

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“…Hydrogen peak heights were recorded and compared with standards. The amount of hydrogen produced during the dissimilation of I mol glucose was calculated from the rate of hydrogen accumulation in the gas phase (Fencl, 1966) using the average of the initial and final volumes of the chemostat and without correcting for the small change in dilution rate; the time taken for the estimate was small compared with the replacement time of the chemostat culture.…”

Section: Introductionmentioning

confidence: 99%

“…The amount of ethanol lost by evaporation from the chemostat culture into the gas phase of the culture vessel was estimated by diverting the effluent gas stream from the culture for 3 h through a Drechsel bottle containing roo ml 8-3 mM-potassium dichromate in 5 M-H,SO,. The remaining potassium dichromate was titrated (Neish, 1957), from which the amount of ethanol lostlml chemostat culture was calculated (Fencl, 1966).…”

Section: Introductionmentioning

confidence: 99%

The Apparent ATP Requirement for Nitrogen Fixation in Growing Klebsiella pneumoniae

Hill

1976

Journal of General Microbiology

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SUMMARYThe apparent ATP requirement for N, fixation in Klebsiella pneumoniae was high (the ATPIN, molar ratio was 29 when estimated in anaerobic glucose-limited chemostat cultures) compared with that determined previously in Azotobacter chroococcum and in Clostridium pasteurianum. The high value was probably not due to unfavourable temperature, phosphate concentration or pH. The apparent ATP requirement for N, fixation was probably no lower in 0,-limited chemostat cultures than in anaerobic glucose-limited chemostat cultures. When hydrogen was introduced into the atmosphere over the anaerobic glucose-limited chemostat culture, there was an increase in the apparent ATP requirement for N, fixation and in the activity of nitrogenase in intact organisms. A comparison of these increases suggests that some ATP is wasted by the ATP-dependent H,-evolving activity of nitrogenase.

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Theoretical Analysis of Continuous Culture Systems

Cited by 54 publications

References 14 publications

Input and volume distributions for continuous cultures

Input and volume distributions for continuous cultures

A Continuous Culture System for Assessing Microbial Activities in the Piezosphere

The Apparent ATP Requirement for Nitrogen Fixation in Growing Klebsiella pneumoniae

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