摘要:

AbstractA microbial ecosystem represents a delicately balanced population of microorganisms each interacting with and influencing the other members of the population. An understanding of the nature and effects of these interactions is essential to improving the performance of these ecologies, which are important, in such diverse processes as biological waste treatment procedures, water pollution abatement, industrial fermentations, human or animaldigestivesprocesses and in soil. There are several types of mocrobial interactions, such as commensalism, inhibition, food competition, predation, parasitism, and synergism, which either singly or in combination may influence the functioning of the microbial ecology.To understand interactions, it is necessary to perform a detailed study of the physiology of the individual predominating microorganisms to establish their requirements with respect to such environmental factors as nutrients, temperature, pH, oxidation‐reduction potential, removal of waste products, or toxic materials which may be involved in control processes and to determine how these factors affect their capabilities. The sum total of this information will indicate the possible interactions between the microorganisms and will form the basis for conducting experiments either in the laboratory or with mathematical models. Such experiments will lead to an understanding of microbial activities and to the formulation of control measures, often using an alteration of the environmental factors for regulation of the microbial ecologies. Extensive research remains to be done on the microbial interact inns in obtain the desired, precise control of these ecological processe

ISSN:0006-3592    

DOI:10.1002/bit.260120302

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

年代:1970

数据来源: WILEY

摘要:

AbstractThe ecological significance of bacterial capsules when virulent bacteriophages are present was explored by exposing continuous cultures ofEscherichia coliATCC 11303, in various stages of capsulation and clumping, to a virulent coliphage, T2. Only partial protection was provided by capsulation, but this could be a factor affecting survival in complex mixed cultures.

ISSN:0006-3592    

DOI:10.1002/bit.260120303

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

年代:1970

数据来源: WILEY

摘要:

AbstractBacteriophages are widely distributed in nature and may be important factors in regulating populations of their hosts. Model continuous culture systems of a single bacterial species and a temperate parasitic phage have been studied. Steady state cultures of lysogenicEscherichia coli159T−(λcts) produced a small quantity of free λ cts phage. Temperature shocking such a culture resulted in a sharp increase in phage concentration with a concomitant fall in cell population. With time the system returned to a steady state condit

ISSN:0006-3592    

DOI:10.1002/bit.260120304

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

年代:1970

数据来源: WILEY

摘要:

AbstractMathematical models of the interaction between predator and host populations have been expressed as systems of nonlinear ordinary differential equations. Solutions of such systems may be periodic or aperiodic. Periodic, oscillatory solutions may depend on the initial conditions of the system or may be limit cycles. Aperiodic solutions can, but do not necessarily, exhibit oscillatory behavior. Therefore, it is important to characterize predatory‐prey models on the basis of the possible types of solutions they may possess. This characterization can be accomplished using some well‐known methods of nonlinear analysis. Examination of the system singular points and inspection of phase plane portraits have proved to be useful techniques for evaluating the effect of various modifications of early predator‐prey models. Of particular interest is the existence of limit cycle oscillations in a model in which predator growth rate is a function of the concentration of

ISSN:0006-3592    

DOI:10.1002/bit.260120305

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

年代:1970

数据来源: WILEY

摘要:

AbstractThe main purpose of the work reported here was to establish the effectiveness of aeration and agitation, and to determine the best conditions of aeration for the growth and production of glucose oxidase ofAspergillus niger, on a semi‐industrial scale. Concentration of dissolved O2, O2consumption and CO2production were measured. It was found that the rate of growth and the activity of glucose oxidase per gram mycelium increased with the increase of speed of agitation. The concentration of dissolved oxygen of the fermentation broth, as well as the rate of respiration (O2consumption and CO2production) increased in direct proportion to the increase of speed of agitation, while assimilation of sugars was accelerated. The values of the respiratory ratio showed a fluctuation according to the presence or absence of sugar in the mediu

ISSN:0006-3592    

DOI:10.1002/bit.260120306

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

年代:1970

数据来源: WILEY

摘要:

AbstractThe enzyme L‐amino acid oxidase ofCrotalus adamanteuswas covalently coupled to porous 96% silica glass particles. The insolubilized enzyme was active on several L‐amino acids including: leucine, isoleucine, cysteine, phenylalanine, tryptophane, and methionine. No activity was observed with D‐amino acids, L‐asparagine, or L‐proline. Maximum activity was observed at pH 7.8. Stability of the enzyme derivative was demonstrated by continuous operation of an enzyme column for 35 days, during which the bound enzyme oxidized over 5000 times its own weight of

ISSN:0006-3592    

DOI:10.1002/bit.260120307

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

年代:1970

数据来源: WILEY

摘要:

AbstractEarlier observations revealed that incubation of media and the attendant changes in oxidation‐reduction potential (ORP) were related to improved cell production. This is a report, of work done to show that the higher levels and increased rates of growth of cells grown in incubated medium are associated with the ORP level of the medium before inoculation of the medium with cells. Work was done using 250‐ml centrifuge spinner bottles as the culture vessels. Further work is needed to establish the desirability of deliberate poising of media prior to use for studies in small vessels and fla

ISSN:0006-3592    

DOI:10.1002/bit.260120308

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

年代:1970

数据来源: WILEY

摘要:

AbstractPrevious studies of oxidation‐reduction potential (ORP) variation in monolayer (Roux bottle) cultures pointed out the need for data on pH and ORP patterns in simple spinner cultures. This information was desirable for optimizing conditions of growth in small 1‐L and New Brunswick fermentors. Results of experiments in 250‐ml centrifuge spinner vessels are presented showing that incubation of media prior to inoculation induces desirable qualities reflected in better growth. The importance of initial ORP values of the medium is discussed. The relationship of ORP levels to yield and longevity of cell growth is also considered. The ORP level of the medium at inoculation is shown to be effected by previous incub

ISSN:0006-3592    

DOI:10.1002/bit.260120309

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

年代:1970

数据来源: WILEY

摘要:

AbstractIn replicated 30 to 40‐ml suspension cultures of rapidly proliferating monkey kidney cells of a comparatively fragile strain, the rates of glucose utilization and lactic acid accumulation averaged about 400 micrograms and 110 micrograms per 106cells per day respectively, with average molar La/Gl ratios of 0.48. These two rates of glucose utilization and lactic acid accumulation were about 4 × and 10 × as high as the corresponding rates in comparable cultures of the hardier strain 2071‐L mouse fibroblasts under the same conditions, with average molar La/Gl ratios of 0.16. In comparable but nonproliferating suspension cultures of the same strain of monkey kidney cells, during about 3 weeks the rates were extremely high, with about 710 micrograms glucose utilized and 445 micrograms lactic acid accumulated per 106cells per day, with average molar La/Gl ratios of 1.37. The rates of glucose uptake and lactic acid accumulation were higher in the nonproliferating cultures aerated with 5% CO2in air than in those aerated with 10% CO2in air. This difference was associated with pH, which was higher in the former group.It was concluded that with this fragile strain of monkey Kidney cells(1) in nonproliferating cultures the cells were metabolizing actively but with a marked tendency to higher La/Gl ratios, (2) in the proliferating cultures the high rates of glucose utilization and lactic acid accumulation were definitely not directly correlated with the rate of growth, and (3) in none of the cultures was the amount of glucose remaining in the fluid at fluid changes so low as to have been a limiting factor.Information in the literature concering glucose utilization and lactic acid production by cellsvitrois voluminous and in some respects contradictory. In the present study the rates were unexpectedly high for the monkey kidney cells, particularly those in the otherwise apparently inactive nonproliferating cultures. The data seem to be unique, in that an established strain of cells in chemically defined medium in suspension cultures has been characterized for these metabolic parameters in both proliferating cultures and in equivalent nonproliferating cultures under directly comparable conditions.The concept was developed that since these monkey kidney cells are obviously more fragile than the other cells examined, the complex physical stresses imposed upon these cells in agitated cultures can be modified and lessened in order to permit growth. Lessening of such mechanical stress waa brought about in several ways, of which only the smaller flask size seemed to be at least partly effective. Increasing either the concentration or the viscosity type of Methocel waa not effe

ISSN:0006-3592    

DOI:10.1002/bit.260120310

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

年代:1970

数据来源: WILEY

摘要:

AbstractA method for analyzing the reactor behavior of a continuous, multistage tower fermentor is described. A model consisting of a system of interconnected, ideal subreactors is set up on the basis of the fermentor's configuration and flow pattern. The residence time distribution curve is used to test the validity of the model and the relative quantities of flow streams and regions in the model are determined. A least‐square fitting procedure between measured and calculated distribution curves is used to identify the proper model. The application of this method to real cultivation conditions is also discussed. Using this approach, the multistage tower fermentor is shown to be equivalent to a cascade of four perfectly mixed tanks with a backtracking stream between stages. The extent of backflow under various conditions has also been determine

ISSN:0006-3592    

DOI:10.1002/bit.260120311

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

年代:1970

数据来源: WILEY