摘要:

AbstractBiofilm development at a surface is the net result of several physical, chemical, and microbial processes including the following: (1)transport of dissolved and particulate matter from the bulk fluid to the surface; (2) firm microbial cell attachment to the surface; (3) microbial transformations (growth, reproduction, etc.) within the biofilm resulting in production of organic matter; (4) partial detachment of the biofilm due primarily to fluid shear stress. This report presents a framework for analyzing the interrelated processes contributing to biofilm development. Some of the available rate and composition data are presented so that the relative process rates can be compared.

ISSN:0006-3592    

DOI:10.1002/bit.260230902

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

年代:1981

数据来源: WILEY

摘要:

AbstractA pulse of substrate solution was applied to an immobilized‐enzyme column, in which the substrate was then converted by reversible or consecutive reactions. Immobilized glucose isomerase was used for the reversible reaction, and immobilized invertase and glucose oxidase for the consecutive reactions. The elution profiles of substrate and product were determined experimentally. These profiles were in good agreement with the ones predicted theoretically. The effect of some parameters on the elution profiles for reversible and consecutive reactions is discusse

ISSN:0006-3592    

DOI:10.1002/bit.260230903

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

年代:1981

数据来源: WILEY

摘要:

AbstractA small reactor of immobilized papain was used to gain some knowledge about the effect of immobilization upon the reactivity of the enzyme towards one substrate and various types of inhibitors. A buffer solution containing benzoyl–arginine ethyl ester as substrate was run through a small column of papain immobilized by attachment to agarose beads. The pH of the effluent was measured continuously and provided the data used to calculate the substrate conversion during passage through the reactor. The operation of the system was checked by determining the substrate conversion as a function of flow rate. It proved to operate as theory demanded. The rate and extent of inhibition were measured after addition of various inhibitors to the buffer–substrate solution. The following quantities of immobilized papain were found to be equal within ±20% to those of the free enzyme in solution: the overall activity, theKmof benzoyl–arginine ethyl ester, theKiof the competitive inhibitor benzoylamino‐acetonitrile, the rate of inactivation by chloroacetic acid and by chloroacetamide, the rate of activation by cysteine of the mixed disulfide of papain and cysteine, and the rate of spontaneous reactivation of the KCNO–papain adduct. The inactivation by KCNO proved to be strongly pH dependent. This may explain why the rate of the latter reaction is only 66% of the rate with free enzyme. It is concluded that the rates and equilibrium constants measured in the present reactor system are within ±20% of the values of the dissolved enzyme, provided that the reactions are not strongly pH dependent. Calculation showed there was no diffusion

ISSN:0006-3592    

DOI:10.1002/bit.260230904

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe effect of the intraparticle diffusion resistance on the apparent stability of the immobilized enzyme suffering from the first‐order deactivation has been studied quantitatively. A general expression for the relationship between the decreasing observed enzymatic reaction rate and the intrinsic enzyme deactivation rate has been introduced. The method to estimate the intrinsic deactivation rate constant also has been proposed. Using the invertases immobilized on a anion‐exchange resin, the theory proposed in this work has been verified experimenta

ISSN:0006-3592    

DOI:10.1002/bit.260230905

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

年代:1981

数据来源: WILEY

摘要:

AbstractExperiments are described in which municipal wastewater is submitted to reverse osmosis. During a test period of two months a tubular apparatus, operated batchwise, maintained its original flux and rejection, the permeate being of good quality as a raw material for drinking water. The wastewater was concentrated 7.7 times. Continuous anaerobic digestion of the brine removed over 90% of the BOD evolving the expected amount of methane. The overall process is considered in its context of environmental and energetic aspects and is compared with a conventional treatment. This reveals clear perspectives for practical application in urban areas.

ISSN:0006-3592    

DOI:10.1002/bit.260230906

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

年代:1981

数据来源: WILEY

摘要:

AbstractCulture filtrates from three mutant strains ofTrichoderma reeseigrown on lactose and on cellulose were compared under use conditions on four cellulose substrates. Cellulose culture filtrates contained five to six times as much cellulase as lactose culture filtrates. Unconcentrated cellulose culture filtrates produced up to 10% sugar solutions from 15% cellulose in 24 h. Specific activity in enzyme assays and efficiency in saccharification tests were low for enzymes from all the mutants. Over a wide range the percent saccharification of a substrate in a given times was directly proportional to the logarithm of the ratio of initial concentrations of enzyme and substrate. As a result of this, dilute enzyme is more efficient than concentrated enzyme, but if high sugar concentrations are desired, very large quantities of enzyme are required. Since the slopes of these plots varied, the relative activity of cellulase on different substrates may be affected by enzyme concentration.

ISSN:0006-3592    

DOI:10.1002/bit.260230907

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

年代:1981

数据来源: WILEY

摘要:

AbstractDextransucrase fromLeuconostoc mesenteroideswas produced in a semicontinuous culture with slow addition of a concentrated sucrose solution. The resulting high activity of the fermentation broth allowed a one‐step purification method, by gel permeation chromatography (GPC) in 96.4% yield. This procedure resulted in 140‐fold purification, with specific activity of 122 U/mg. The enzyme was immobilized onto an amino‐Spherosil support activated with glutaraldehyde. Preparations with dextransucrase activities as high as 40.5 U/g of support were obtained, when low specific area supports were used and maltose was added during the enzyme coupling. Diffusional limitations were found during enzyme reaction, as shown by a kinetic study. As a consequence of immobilization, the average molecular weight of dextrans seems to increase. Immobilized dextransucrase looks promising for low‐molecular‐weight dextran production. Clinical dextran was synthesized when the polysaccharides produced in the presence of maltose were used as acceptor of a second synthesis reaction. The molecular weight distribution of the resulting production was less disperse than when clinical dextran was produced by acid hydrolysis of high‐molecular‐w

ISSN:0006-3592    

DOI:10.1002/bit.260230908

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe uptake of phenol by pure cultures ofPseudomonas putidagrowing on phenol in continuous culture has been studied. The purpose of the experiments was to determine the kinetic parameters governing uptake of phenol by organisms growing on phenol in the high‐conversion range by measuring uptake rates per unit biomass per unit time at various phenol concentrations. The microorganisms used were taken from a chemostat at residence times of 8, 5.25, 3.85, 3.2, 3, and 2.7h. The Monod–Haldane model and modifications of it were applied to the data and the best kinetic parameters were determined by nonlinear least‐squares techniques. The best model was a two‐parameters simplification of Monod–Haldane in which μ =K1S/(K2+S2). The value ofK1was found to increase monotonically with the value of phenol concentration in the original chemostat with an apparent induction “threshold

ISSN:0006-3592    

DOI:10.1002/bit.260230909

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe method of Thornton and Dulong's formula for estimating heats of combustion are compared in this work. Heats of combustion predicted by Thornton's method for renewable resources such as wood, straw, and municipal solid wastes are considerably closer to experimentally measured values compared to values predicted by Dulong's formula. Thornton's method states that the heat of combustion is directly proportional to the quantity of oxygen consumed in the combustion process. A method which utilizes the weight fraction carbon on a dry basis and the reluctance degree to predict the heat of combustion of renewable resources is presented.

ISSN:0006-3592    

DOI:10.1002/bit.260230910

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

年代:1981

数据来源: WILEY

摘要:

AbstractA feedback control system of the glucose feed rate in a bakers' yeast fed‐batch culture was developed by keeping the ethanol concentration constant. A PID controller and on–off controller were applied and discussed with the aid of the porous Teflon tubing method. Experimental results showed the effectiveness of the control system for avoiding the glucose effect and glucose starvation. It was shown that the feedback control system developed hare could achieve a maximum specific growth rate of 0.3 h−1or a maximum cell yield of 0.5 g cell/g glucose in the fedhyphen;batch cu

ISSN:0006-3592    

DOI:10.1002/bit.260230911

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

年代:1981

数据来源: WILEY