Morphological measurements on Penicillium chrysogenum broths by rheology and filtration methods

The morphology parameters of mycelial culture (Penicillium chrysogenum) were measured and quantified by rheology and filtration methods. Two of the morphology parameters obtained from rheology measurements, delta defined by the Casson equation and delta* defined by intrinsic viscosity, were found to vary systematically with broth age and with the observed morphology by microscopy. Three of the filtration parameters, hyphal density, Kozeny constant, and index of compressibility, are demonstrated as sensitive indicators of the broth age and mycelial morphology. Two of the morphology parameters, delta and delta*, were used to cross-correlate with hyphal density. Because various mycelial fermentations require different growth morphologies (pellet and filament) for optimum product yield and the morphology of mycelial broths varies with broth age, it is suggested that these morphology parameters could be used to represent the morphology of mycelial broths quantitatively. (c) 1993 John Wiley & Sons, Inc.     

Direct measurement of the yield stress of filamentous fermentation broths with the rotating vane technique

The existence of a yield stress in filamentous fermentation broths has important transport phenomena implications in the design and operation of bioreactors. In this study, the constant shear rate vane method was assessed for directly measuring the yield stress of filamentous Aspergillus niger fermentation broths, as well as model fluids (ketchup, yogurt, and pulp suspensions). The method involved rotating 4-, 6-, and 8-bladed vanes (7.2 cm 相似文献   

Morphological measurements on filamentous microorganisms by fully automatic image analysis

Characterization of mycelial morphology is important for physiological and engineering studies of filamentous fermentations, and in the design and operation of such fermentations. Image analysis has been developed as a method for this characterization, and has been shown to be faster and generally more accurate than previous methods. A fully automatic system has been developed, in which speed is gained, but with loss of accuracy in some cases. The method has been tested on Streptomyces clavuligerus and Penicillium chrysogenum P1 batch fermentations. It has also been tested on a fed-batch Penicillium chrysogenum P2 fermentation, in which the medium contained solid ingredients. Fully automatic image analysis for morphological characterization of filamentous microorganisms is an important development which will make practical many engineering and physiological studies of such fermentations that have so far not been completely satisfactory.     

The use of image analysis for morphological measurements on filamentous microorganisms

Characterization of mycelial morphology is important for the design and operation of filamentous fermentations. Initial investigations have been made of semiautomated image analysis as a replacement for a digitizing-table method. It was shown that the image analysis method was more precise than the digitizing-table method used, although this extra precision is unimportant in this application. On average, image analysis gave mean hyphal lengths 6% greater than digitizing, because the latter used chord lengths to represent are lengths. For short branches image analysis was less accurate. In time and convenience the image analysis method had an overwhelming advantage, and this advantage might be enhanced by full automation. The resulting ability to characterize mycelial morphology rapidly would permit such characterization to be used routinely in studies of filamentous fermentations.     

Surface tension effects on instability in viscoelastic respiratory fluids

This paper establishes the mathematical formalism for the modeling of the mucus layer in the human trachea as a viscoelastic multiphase fluid system with surface tension with a view toward study of instability properties of the air-mucus system aimed at improving the design of new bioaerosol suppressing medication. The effects of surface tension, previously only conjectured and very poorly understood, are clearly established with quantitative relationships. Several very important physiological conclusions are obtained supporting one method of potential treatment and prevention of disease transmission by alteration of the mucus layer properties over other potential methods.     

Determination of the Surface tension of proteins. I. Surface tension of native serum proteins in aqueous media

The desorption patterns of serum proteins in hydrophobic chromatography suggest that serum proteins that remain immersed in an aqueous medium and do not become in a protein-air interface are very hydrophilic. Contact angle measurements on fairly thick layers of hydrated serum proteins, formed on ultrafiltration membranes, yield surface tensions that correlate well with the degree of hydrophilicity derived from desorption data obtained by hydrophobic chromatography. For further confirmation the absorptivity of four human serum proteins was measured with respect to surfaces of different polymers of various surface tensions, for solution in aqueous solvents of different surface tensions. The surface tension of the solvent from which a dissolved protein adsorbs to precisely the same extent onto all solid substrates (regardless of their surface tensions) is equal to the surface tension of that protein. The surface tensions found by the contact angle (first value given) and by the protein adsorption methods (second value given) were. in erg/cm2; alpha 2-macroglobulin, 71.0, 71.0; serum albumin, 70.5, 70.2; immunoglobulin M, 69.5, 69.4; immunoglobulin G, 67.4, 67.7.     

pH modelling in fermentation broths

A model of broth pH has been established based upon the mineral requirements of the microorganism, the substrate consumption and the metabolites production. It has been tested on acetic acid, citric acid and yeast fermentations. It has then been used to predict the mineral composition of the feed for fedbatch growth of Saccharomyces cerevisiae.     

Surface tension and the dodecahedron model for lung elasticity

Macroscopic elastic moduli governing the incremental deformations of lung parenchyma are calculated on the basis of a model for an individual lung element in the shape of a regular dodecahedron. Elastic stiffness within the element is provided by pin-jointed tension members along the edges of the dodecahedron, surface tension is incorporated into its pentagonal faces, and the influence of transpulmonary pressure is simulated by an externally applied hydrostatic tension. The analysis is based on a variational statement of nonlinear structural mechanics, and the results show how the moduli depend on the effective inflation pressure, the constitutive behavior of the idealized truss members, and the surface-area dependent surface tension. The theory is discussed in the light of available experimental information. A more general analysis is needed to account for the effects of structural as well as surface-tension hysteresis.     

Influence of contractile tension development on dynamic strength measurements of the plantarflexors in man

The influence of the contractile tension rise time on isokinetic force-angle records has been inferred from static force-time curves but has not been experimentally determined. The purpose of this study is thus to describe the influence of the contractile rise time on the force-angle curves produced during maximal voluntary, acceleration controlled, isokinetic plantarflexions at 30 degrees/s. Since we could not measure directly the period of force development unbiased by changes in muscle length during the movements, we devised an experimental strategy which allowed the computation of the dynamic force-time curve. Thus in five normal men, we first recorded force-angle curves produced during maximal voluntary plantarflexion movements preceded by maximal static pre-loading (D:-10 degrees Max) in order to eliminate the period of tension development from the force-angle record. Next, we recorded force-angle curves produced during maximal voluntary contractions initiated from two different starting angles without pre-loading (D:-10 degrees Min and D:0 degrees Min) to include the period of tension rise. The dynamic force-time curve was computed by correcting these force-angle curves (D:-10 degrees Min and D:0 degrees Min) for the hypothetical loss in force due to muscle shortening. We compared the relative (to remove the effects of force magnitude) computed dynamic force-time curves with relative static force-time curves measured at three different angles. We found the shape and several other parameters of all three static and both computed dynamic force-time curves to be similar (p greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)