摘要:

AbstractA fairly general model of the biochemical oxidation, which takes into account the activity of microorganisms, is presented. Parameters of the model have been determined by fitting the model to available experimental data through the use of a straightforward gradient technique.

ISSN:0006-3592    

DOI:10.1002/bit.260110502

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

年代:1969

数据来源: WILEY

摘要:

AbstractA temperature‐synchronized, semi‐continuous culture and monitoring system is described, with results from use of the system for autotrophically growingEuglena. Outflow from the culture vessel consists of measured samples taken automatically at 2‐hour intervals and fixed for later counting. Inflow is by siphon feed, which restores the culture level after each sampling. The interpretation of growth curves obtained from such cultures is discussed from the viewpoint, of division synchrony and cell cycle studies, and some general comparisons are made between batch and continuous cultures for such st

ISSN:0006-3592    

DOI:10.1002/bit.260110503

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

年代:1969

数据来源: WILEY

摘要:

AbstractA mathematical model for the prediction of product formation in batch processes is presented. The suggested procedure allows production of a prognose at any given moment of a run concerning the product concentration at any future moment of the same experiment. The series of subsequent prognoses thus produce a trend, and it is assumed that an analysis of the trend may provide information, which is useful in the evaluation of different decision alternatives in pilot plant batch experiments.

ISSN:0006-3592    

DOI:10.1002/bit.260110504

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

年代:1969

数据来源: WILEY

摘要:

AbstractA microprobe electrode was used to determine dissolved oxygen concentrations near the surface and within a bacterial slime mass supplied with a continuous flow of nutrient solution. With dilute medium, the oxygen profile became level at high concentrations within the film, indicating substrate‐limited respiration. More concentrated medium caused the profile to fall to low oxygen concentrations characteristic of oxygen‐limited respiration. Oxygen responses to sudden changes in concentration of nutrient medium were measured. Estimates of microbial respiration rate and of diffusivity of oxygen were based on well‐known diffusion equa

ISSN:0006-3592    

DOI:10.1002/bit.260110505

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

年代:1969

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260110506

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

年代:1969

数据来源: WILEY

摘要:

AbstractWith a chemostat culture, both the bacterial growth rate and the growth environment can be independently varied between wide limits. Changing the growth rate ofAerobacter aerogenesorganisms (in either a glycerol‐limited medium or a Mg2+‐limited medium) affected the bacterial cell wall content; invariably slow growing organisms were smaller than faster growing ones and had a higher cell wall/biomass ratio. Changing the growth rate also influenced the composition of the walls but in this respect glycerol‐limited organisms and Mg2+‐limited organisms behaved differently. Thus, whereas increasing the growth rate of glycerol‐limited cultures caused the cell wall 2‐keto‐3‐deoxyoctonic acid (KDO) and heptose contents to increase progressively, with Mg2+‐limited cultures they decreased. Furthermore, although KDO and heptose are both components of the lipopolysaccharide layer, their ratio varied with growth rate, and with the nature of the growth‐limitation, indicating changes in the lipopolysaccharide composition. These results are discussed with particular reference to the influence of environment on cell wall content and composition, and the use of continuous culture for the production of

ISSN:0006-3592    

DOI:10.1002/bit.260110507

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe physiology ofAspergillus nidulansstrain 224 has been studied under conditions of batch‐ and glucose‐limited chemostat‐culture and the effect of different steady state growth rates and dissolved oxygen tensions (DOT) examined. Measurements of the specific activities of selected glucose enzymes, the extent of oxygen uptake inhibition by glycolytic inhibitors, and radiorespirometric analyses were made in order to follow the variations in glucose catabolism, which occurred under these conditions. Greatly increased activity of the hexosemonophosphate (HMP) pathway was found during: (i) exponential growth of batch cultures; (ii) at near maximum specific growth rates (μ = 0.072 hr−1) (DOT = 156 mm Hg); and (iii) at low DOT levels (<30 mm Hg) (μ = 0.050 hr−1) in chemostat cultures. These changes in glucose eatabolism have been discussed in terms of the biosynthetic demands of the fungus under the influence of changing growth pressures. Preliminary studies also have been made of transition state behavior following stepwise alteration of the DOT. A new steady state was established after 4–5 culture doublings during which period an “overshoot” in HMP pathway activity occurred; these kinetics are indicative of a derepression of certain glucose enzymes. Low molecular weight phenols are synthesized during the exponential phase in batch cultures and these are further metabliized to a major secondary metabolite, melanin, at the onset of stationary phase conditions. The kinetics of tyrosinase production in steady state chemostats differs from those that might be predicted for an enzyme associated solely with secondary metabolism. A primary physiological role for this oxidase inAspergillus nidulansha

ISSN:0006-3592    

DOI:10.1002/bit.260110508

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

年代:1969

数据来源: WILEY

摘要:

AbstractA fermentation system was designed and constructed to study the growth characteristics of microorganisms at low and high cell concentrations. The technique used to develop high cell densities utilized a rotating microfiltration unit to permit the removal of cell‐free product from the fermenter. The fermenter volume and the filter were contained in a single unit composed of a series of concentric cylinders. Annuli contained the fermenter volume while the second outermost cylinder supported a microfiltration membrane. Feed to the system was pumped at constant rates, and the internal pressure built up to a value, which would effect the required filtration rate. The system was operated batchwise and continuously with and without filtration.The anaerobie growth characteristics ofStreptococcus faccaluswere determined at 37°C and pH 7.0 for batch, continuous, and continuous with filtration modes of operation. The growth characteristics were unchanged when the cell density was increased. Changes in cell yield peer model of glucose consumed were clearly illustrated during thee course of single run by operating the fermenter in the unsteady state with filtration. No consumption of glucose for developed was 40% packed cell volume, a value 45 times larger than could be grown in simple batch cultu

ISSN:0006-3592    

DOI:10.1002/bit.260110509

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

年代:1969

数据来源: WILEY

摘要:

AbstractContinuous phased growth produces a culture in which most of the cells in the population are in the same stage of their development. The cell, thereby amplified by the size of the synchronous population, may be examined in the phased culture at any desired growth rate. Changes taking place in the cell after the cell cycle, i.e., post‐cycle changes, may be examined by a modification of the procedure. Further systematic applications of the method permit a rational approach to problems of cell growth and metabolism.The phasing technique recognizes the cells as the fundamental unit for experimental investigation, and offers a great potential in the analysis of the cell throughout its cycle, a relatively unexploited field in cell physiology and fermentation. Experiments with yeasts and bacteria illustrate some of the applications and progress made so fa

ISSN:0006-3592    

DOI:10.1002/bit.260110510

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

年代:1969

数据来源: WILEY

摘要:

AbstractContinuous culture in a cascade of vessels with the addition of supplemental nutrients to any stage permits adjustment of the physiological state of the culture in each stage to best achieve a desired performance goal. The yeastSaccharomyces cerevisiaein two‐stage continuous cultivation was selected as a model system. With conditions in the first stage held constant‐ at a selected glucose concentration in the feed stream, dilution rate for the second stage was varied. Cell numbers, dry weight, glucose concentration, respiration coefficient, and titers of several enzymes were determined. The seed rate was defined as the ratio of glucose concentration in the feeds to stage 1 and to stage 2. At low seed rates, the calculated specific growth rate in the second stage was proportional to dilution rate. At higher seed rates, the specific growth rate based on dry weight behaved differently from that based on cell numbers, and the dependence on dilution rate was not lin

ISSN:0006-3592    

DOI:10.1002/bit.260110511

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

年代:1969

数据来源: WILEY