摘要:

AbstractThe morphology of yeast cells as it is affected by the glycosidic linkages of constituent glucan was studied. Four different strains ofSaccharomyces cerevisiaewere studied. A cell wall matrix particle representing the intact original morphology and composed entirely of β‐glucan was prepared. Using prepared cell wall glucan particles, the morphology and cell wall matrix structure were examined. Genetic modification of the cell wall structure during growth results in the alteration of the shape and hydrodnamic volume of the intact cell wall particles. The shape and hydrodynamic volume of the cell wall particles can also be modified byin vitrochemical and enzymatic treatment. The shape factor and hydrodynamic volume of the whole glucan cell wall matrix particles were evaluated quantitatively using a rheological analysis. An increased degree of β(1 → 6) cross‐linking in the cell wall matrix induces a nearly 2‐fold increase in the shape factor and a 10‐fold increase in the compression modulus of the glucan particles. The disruption of β(1 → 6) glycosidic cross‐linking causes the particles to swell by up to 18% of their original volume. This was used as a strategy to isolate a yeast mutant with a high β(1 → 6) glycosidic content in t

ISSN:0006-3592    

DOI:10.1002/bit.260280602

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe problem of dilute solvent concentration in butanol‐acetone fermentations can be solved by using reverse osmosis to dewater the fermentation liquor. Polyamide membranes have a potential application in a butanol‐acetone fermentation and exhibited rejection rates as high as 98%. Optimum rejection of butanol in the fermentation liquor occurred at recoveries of 20–45%. Flux ranged from 0.05 to 0.6 L m

ISSN:0006-3592    

DOI:10.1002/bit.260280603

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

年代:1986

数据来源: WILEY

摘要:

AbstractMaterial balances for pentosan, lignin, and hexosan, during steam‐explosion pretreatment of aspenwood, showed almost quantitative recovery of cellulose in the water‐insoluble fraction. Dilute acid impregnation resulted in more selective hydrolysis of pentosan relative to undesirable pyrolysis, and gave a more accessible substrate for enzymatic hydrolysis. Thermocouple probes, located inside simulated aspenwood chips heated in 240°C‐saturated steam, showed rapid heating of air‐dry wood, whereas green or impregnated wood heated slowly. Small chips, 3.2 mm in the fiber direction, whether green or airdry gave approximately equal rates of pentosan destruction and solubilization, and similar yields of glucose and of total reducing sugars on enzymatic hydrolysis withTrichoderma harzianum. Partial pyrolysis, destroying one third of the pentosan of aspenwood at atmospheric pressure by dry steam at 276°C, gave little increase in yield of reducing sugars on enzymatic hydrolysis. Treatment with saturated steam at 240°C gave essentially the same yields of glucose and of total reducing sugars, and the same yields of butanediol and ethanol on fermentation withKlebsiella pneumoniae, whether or not 80% of the steam was bled off before explosion and even if the chips remained intact, showing that explosion was u

ISSN:0006-3592    

DOI:10.1002/bit.260280604

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

年代:1986

数据来源: WILEY

摘要:

AbstractDesigning a fluidized‐bed bioreactor requires choosing the best support particle (if any). Effectiveness factors (proportional to reactor volumetric productivity) are derived for flocs, solid spherical supports, porous supports, and adsorbent supports. The derivation demonstrates a mathematical procedure for reducing the diffusion/uptake equations for many components (substrates and inhibitory products) to a single equation, and for identifying the limiting component. With solid supports there exists a film thickness that maximizes the effectiveness, and the design objective is to keep the film near this optimum throughout the bed. This involves consideration of the effect of support particle density and film growth on bed stratification. Other considerations in picking support particles are obtaining reasonable values for bed height and diameter, minimizing mass transfer resistance between liquid and biomass, and preventing surface shear from stripping off the biomas

ISSN:0006-3592    

DOI:10.1002/bit.260280605

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

年代:1986

数据来源: WILEY

摘要:

AbstractRemoval and modification of southern red oak hemicelluloses and lignin in a 0.05%(w/v) sulfuric acid hydrolysis were investigated. The hydrolysis profile was to raise the reaction from room temperature to 150°C for in 38 min and to extend the hydrolysis at 150°C for 1 h. At the end of the hydrolysis, 25.5% of red oak components were dissolved, of which 58% was xylose and 17% lignin. As the hydrolysis proceeded from room temperature to 150°C, a part of red oak xylan was removed to yield an oligomer fraction having maximal yield and average molecular weight of 3460 at 150°C. This fraction and the bulk xylan extracted during the first 30 min at 150°C were further degraded to give a lower molecular weight oligomer fraction, of which the yield and average molecular weight (2610) were highest at the end of the bulk removal of xylan. Red oak lignin, syringyl and guaiacyl units in particular, was increasingly removed with the progress of the hydrolysis. Lignin derivatives and a part of red oak extractives soluble in the hydrolysate were identi

ISSN:0006-3592    

DOI:10.1002/bit.260280606

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

年代:1986

数据来源: WILEY

摘要:

AbstractThis article concerns the development of a simple yet effective procedure for optimizing the design of a reactor system employing CSTRs in series. The basic approach used in this work was to translate the problem of reactor design to a mathematical programming model. The resulting model was then solved by dynamic programming. The procedure was tested on an IBM 3033 computer and an IBM PC‐compatible machine, the CORONA PC‐II microcomputer. The results of this study indicate that the optimization procedure developed is very effect

ISSN:0006-3592    

DOI:10.1002/bit.260280607

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe effects of temperature and inlet pH of the medium on the ethanol productivity and activity of the immobilizedZ. mobiliscells during continuous fermentation of glucose have been studied at various temperatures and pH. On changing the temperature from one steady state level to a new one, 6–8 h were required in order to fully experience the effect of a change in temperature; whereas 8–20 h were required on changing the pH. The optimum temperature of 37°C and a broad pH range of 4.4–6.0 were observed for maximum ethanol productivity and ethanol

ISSN:0006-3592    

DOI:10.1002/bit.260280608

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe diffusivities of glucose and ethanol in cell‐free and cell‐occupied membranes of calcium alginate were measured in a diffusion cell. The lag time analysis was used. Diffusivities decreased with increasing alginate concentration and were comparable with those in water for a 2% alginate membrane. Glucose and ethanol concentrations had no effect on the respective diffusion coefficients. The ratio of ethanol diffusivity to glucose diffusivity in 2 and 4% alginate agreed closely with the inverse ratio of the hydrodynamic raii for the two molecules in water, indicating that the hydrodynamic theory of diffusion in liquids may be applicable to diffusion in dilute alginate gels. Also, the presence of 20% dead yeast cells had no effect on the diffusivities. The data reported can be used to study reaction and diffusion in immobilized cell reactors and cell physiology under immobilized conditi

ISSN:0006-3592    

DOI:10.1002/bit.260280609

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

年代:1986

数据来源: WILEY

摘要:

AbstractAn experimental design to estimate the parameters in a Monod‐type equation from batch culture data was examined. Consideration was given to the design of experiments to estimate accurate values of the parameters. Sequential experimental design with the information index was used for this purpose. With this approach the standard deviation of the parameter values was reduced using simulated batch culture dat

ISSN:0006-3592    

DOI:10.1002/bit.260280610

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

年代:1986

数据来源: WILEY

摘要:

AbstractA novel 2‐L bubble column was used to study the continuous, immobilized cell production of thienamycin. Cells ofStreptomyces cattleyawere immobilized by culturing them in an appropriate growth medium containing 60/80 mesh celite particles. The dilution rate used during the continuous growth phase was 0.2 h−1. This growth phase was terminated upon the development of heavy cell films (100–500 μm thickness), and the medium was replaced with an appropriate thienamycin production medium. The system was then operated in a batch mode until thienamycin production began. At that time, continuous feeding of the production medium was initiated and the influence of medium composition and dilution rate on CO2, NH4, biomass, and thienamycin production investigated. With synthetic production medium, a doubling of the dilution rate from 0.05 to 0.10 h−1resulted in a doubling of the thienamycin volumetric productivity. Rates of CO2and NH4production increased by ca. factors of three and two, respectively. The rate of PO4utilization also doubled. When the dilution rate was decreased to 0.05 h−1, the rates of CO2production and PO4utilization quickly decreased (i.e., within 3 h). The rates of NH4and thienamycin production also decreased but more slowly (i.e., ca. 100 h after the decrease in dilution rate). With complex production medium, the rates of CO2production and PO4utilization appeared to be a direct function of dilution rate at the dilution rates tested. Thienamycin production in this case was not a function of dilution rate. Comparing the synthetic medium with the complex medium at either dilution rate, the volumetric rate of thienamycin production was higher in the system being fed complex medium. However, the specific activity (units thienamycin/g cell/h) observed with complex medium was lower than that observed with synthetic medium. The higher volumetric productivity observed with complex medium was the result of a high cell loading. The above observations will be discussed in terms of control of thienamycin synthesis and film thickne

ISSN:0006-3592    

DOI:10.1002/bit.260280611

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

年代:1986

数据来源: WILEY