摘要:

AbstractGeneral expressions for mass, elemental, energy, and entropy balances are derived and applied to microbial growth and product formation. The state of the art of the application of elemental balances to aerobic and heterotrophic growth is reviewed and extended somewhat to include the majority of the cases commonly encountered in biotechnology. The degree of reduction concept is extended to include nitrogen sources other than ammonia. The relationship between a number of accepted measures for the comparison of substrate yields is investigated. The theory is illustrated using a generalized correlation for oxygen yield data. The stoichiometry of anaerobic product formation is briefly treated, a limit to the maximum carbon conservation in product is derived, using the concept of elemental balance. In the treatment of growth energetics the correct statement of the second law of thermodynamics for growing organisms is emphasized. For aerobic heterotrophic growth the concept of thermodynamic efficiency is used to formulate a limit the substrate yield can never surpass. It is combined with a limit due to the fact that the maximum carbon conservation in biomass can obviously never surpass unity. It is shown that growth on substrates of a low degree of reduction is energy limited, for substrates of a high degree of reduction carbon limitation takes over. Based on a literature review concerning yield data some semiempirical notions useful for a preliminary evolution of aerobic heterotrophic growth are developed. The thermodynamic efficiency definition is completed by two other efficiency measures, which allow derivation of simple equations for oxygen consumption and heat production. The range of validity of the constancy of the rate of heat production to the rate of oxygen consumption is analyzed using these efficiency measures. The energetic of anaerobic growth are treated—it is shown that an approximate analysis in terms of an enthalpy balance is not valid for this case, the evaluation of the efficiency of growth has to be based on Gibbs free energy changes. A preliminary analysis shows the existence of regularities concerning the free energy conservation on anaerobic growth. The treatment is extended to include the effect of growth rate by the introduction of a linear relationship for substrate consumption. Aerobic and anaerobic growth are discussed using this relationship. A correlation useful in judging the potentialities for improvement in anaerobic product formation processes is derived. Finally the relevance of macroscopic principles to the modeling of bioengineering systems is discusse

ISSN:0006-3592    

DOI:10.1002/bit.260221202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe kinetics of oxidation of glucose solution by dissolved oxygen in the presence of glucose oxidase and excess catalase were studied both theoretically and experimentally. The kinetic model used was based on the detailed mechanism of the reaction. The description of the model is given by the Michaelis–Menten equation for the case of two substrates. The experiments were carried out in a closed reactor at a temperature of 25°C and pH 5.55. Commercial enzymes were used. Kinetic constants of the reaction were evaluated by fitting the oxygen concentration profiles calculated from the model to those found experimentally, by the method of nonlinear regression. The rate ofD‐glucose mutarotation to α and β form, and distortion of data caused by the dynamics of the applied oxygen probe were taken into account. The determined kinetic constants of the reactions are in good agreement with those given in the literature for purified enzymes. Adoption of literature kinetic data of this reaction to the determination of aeration capacity of fermentors by means of glucose oxidase systems has proved po

ISSN:0006-3592    

DOI:10.1002/bit.260221203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractA balance of electrons available from acetic acid consumed for growth and oxygen uptake in the aerobic‐ and photoheterotrophic growth ofRhodopseudomonas sphaeroidesS on acetate‐minimal medium could be realized the same as in the carbon balance. The unmeasured amounts of yeast extract consumed by the cells grown on propionate–yeast extract media were indirectly estimated from the balance equation of electrons available from carbon substrates. The specific consumption rate of the yeast extract increased with an increase in propionate consumption rate in aerobic and photoheterotrophic cultures. Growth yields from acetic acid and from propionic acid plus yeast extract were calculated on the electron level, i.e.,YX/aveg cell produced/equivalent electrons available from substrate consumed.YX/avevalues were 5.0 to 5.8 g cell/ave in photoheterotrophic cultures and 2.7 to 3.6 in aerobic–heterotrophic cultures regardless of different medium compo

ISSN:0006-3592    

DOI:10.1002/bit.260221204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe cell envelope of aSulfolobus‐like microorganism has an arrayed hexagonal subunit structure, a double‐layered cytoplasmic membrane, and a hollow periplasmic space between the plasma membrane and the outermost arrayed layer. A dense peptidoglycan layer outside the plasma membrane found in the case ofThiobacillus ferrooxidanswas not seen. The cell envelope of a thermophile isolated from a leaching environment has a well‐defined envelope with two well‐stained layers distinclty seen. While the peptidoglycan layer is also not seen in this thermophile, a long flagellum similar to that in the case ofT. ferrooxidansis present. The presence of pili in theSulfolobus‐like organism and its arrayed subunit cell envelope structure could account for the organism's selective attachment to sulfide phases in the leaching of low‐grade ores. The observations of a well‐defined cell envelope in the two thermophiles is consistent with the structure‐function relationship previously established for

ISSN:0006-3592    

DOI:10.1002/bit.260221205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractUp to three stable steady states are possible in a simple commensalistic system, taking place in an open‐loop mixed reactor when the growth rates of the two species are inhibited by the substrates they prey on (Self‐inhibition). Two stable states are possible in a system with noncompetitive inhibition of the species by the substrate they are not preying on (cross‐inhibition). A large number of steady states as well as oscillatory states are possible when both self‐ and cross‐inhibition are strong. Multiplicity of steady states is also possible in a reactor with biomas recirculation for these kinetics. Yet, the latter is more stable than the open‐loop reactor in the sense that the domain of steady‐state multiplicity is narrower. The stability of steady states and the dynamics of the systems for each of the investigated kinetics are summarized in a qualitative phase plane. The importance of the analysis for improving the selectively and yield of the system and for predicting the response of the system to changes in the operating conditions,

ISSN:0006-3592    

DOI:10.1002/bit.260221206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe design of a 125 liter aerated recirculating tower fermentor is presented. The tower has an external recirculation loop and a broth take‐off point designed to give selective retention of biomass in the fermentor. This allows operation with high throughput rates using a low conentration feed. The aspect ratio in the main tower is approximately 14:1, but good mixing is promoted by the rapid recirculation of the broth. The construction of the fermentor and costs are given in details, illustrating that the fermentor may offer a cheap alternative to conventional system

ISSN:0006-3592    

DOI:10.1002/bit.260221207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe effect of continuous and discontinuous phosphate stress on the observed cell yield coefficient was investigated in a petrochemical pure‐oxygen wastewater treatment plant. A continuous phosphate stress in the activated‐sludge system resulted in a reduction of sludge production by 36%, but no improvement of the effluent quality was noticed compared with that of nonstress treatment. However, discontinuous phosphate stress produced a high‐quality effluent due to the excellent setting settling properties of the sludge flocs. In addition, the observed cell yield coefficient and concomitantly the sludge production remained 45% below normal. The introduction of the discontinuous phosphate stress in the pure‐oxygen activated‐sludge plant at the BP Chemicals works in Antwerp resulted in a 24% reduction of the total wastewater treatment operat

ISSN:0006-3592    

DOI:10.1002/bit.260221208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractA hydrogen‐producing bacterium,Clostridium butyricum, was immobilized in polyacrylamide gel membrane, agar gel membrane, and collagen membrane. The apparatus consisted of a compartment(I or II) and a whole‐cell‐entrapped gel membrane which was placed in the center of the two compartments. The behavior of hydrogen through whole‐cell‐entrapped gel membrane was examined for improving the sensitivity of a microbial BOD sensor and the efficiency of biochemical fuel cells. The bacteria‐polyacrylamide gel membrane produced a higher amount of hydrogen in compartment II than the other bacteria‐entrapped gel membranes. The apparent diffusion constant decreased with increasing bacteria contents in the gel membrane. As a result, 100 mg wet cells/g gel was the maximal bacteria content in the membrane for the production of hydrogen. Twenty percent of the hydrogen evolved by the whole cells diffused to compartment II, and there was a linear relationship between the glucose concentration in a bulk solution (compartment I) and the rate of hydrogen diffused to c

ISSN:0006-3592    

DOI:10.1002/bit.260221209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractA differential microrecirculation reactor was developed for kinetic analysis of both soluble and immobilized enzymes. The reactor system was easliy fabricated with in the laboratory from readily available materials. The disposable, small reactors allowed forin situweight determination of the enzyme beads. Routinely, only a 1 ml liquid volume of substrate was used for each kinetic assay. The reactor system was also used for determination of partition coefficients. Both uses of the reactor system required only 5–10 min for completion of a given determinatio

ISSN:0006-3592    

DOI:10.1002/bit.260221210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractA flat‐membrane dialyzer was used as enzyme reactor by introducing enzyme solution into one of the membrane‐separated chambers. The apparent Michaelis constantKm(app) of urease was always larger (ten times at [urease] = 1 mg/ml) than that of free enzyme because the permeation of substrate through the membrane was rate determining.Km(app) for urease decreased from 125 to 20mMwith increasing flow rate of the substrate solution because of the turbulent flow near the membrane. In the case of glucose oxidase or creatine kinase, the reaction rate was limited by the permeation of less permeable substrates such as oxygen or ATP. Therefore,Km(app) of more permeable substrates such as glucose or creatine became smaller than that of free enzyme. The reaction amount calculated from the permeation data agreed well with experimental results. By designing spacers for the reactor to give turbulence to the solution, the effectiveness of the reactor was improved fivef

ISSN:0006-3592    

DOI:10.1002/bit.260221211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY