摘要:

AbstractThe production of ethanol from starch by a coimmobilized mixed culture system of aerobic and anaerobic microorganisms in Ca‐alginate gel beads was investigated. The moldAspergillus awamoriwas used as an aerobic amylolytic microorganism and an anaerobic bacterium,Zymomonas mobilis, as an ethanol producer. By controlling the mixing ratio of the microorganisms in the inoculum size, a desirable coimmobilized mixed culture system, in which the aerobic mycelia grew on and near the oxygen‐rich surface of the gel beads while the anaerobic bacterial cells mainly grew in the oxygen‐deficient central part of the gel beads, was naturally established under the aerobic culture conditions, and ethanol could be directly produced from starch by the system. The ethanol productivity by the system in flask culture was particularly affected by the shear stress (dependent on the shaking speed) which controlled the mycelial growth on the surface of the gel beads. Under optimum culture conditions in the flask culture, the glucose produced was instantly consumed, and was not observed in the culture broth; the final concentration of ethanol produced from 100 g/L starch was 25 g/L and the yield coefficient for ethanol,Ypls, was 0.38. The ethanol productivity by the coimmobilized mixed culture system was compared with those by other various culture systems and the advantages of the system were clar

ISSN:0006-3592    

DOI:10.1002/bit.260281202

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

年代:1986

数据来源: WILEY

摘要:

AbstractA relatively simple and inexpensive anaerobic calorimeter was designed and evaluated by using a Hy‐Cal Engineering BI‐7 bidirectional heat‐flux sensor to measure heat output from magnetically stirred I‐L flask fermentations. The production of ethanol and cumulative heat output byZymomonas mobiliswere both linearly proportional to glucose concentrations up to

ISSN:0006-3592    

DOI:10.1002/bit.260281203

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe irradiation with visible light of a photosensitizer dye like methylene blue was used to regenerate by electron transfer the oxidized form of a pyridine nucleotide coenzyme (NAD+). The process has been studied on a common enzymatic reaction: ethanol oxidation by alcohol–NAD+oxidoreductase immobilized on polyacrylamide gel or porous glass balls. In the experimental conditions used, the initial NAD+recycling rates were 2.33 × 104cycles/h (polyacrylamide) and 3 × 104cycles/h (glass balls). A total number of 49.5 × 104cycles was obtained for 13 runs of 2 h. The enzyme immobilization strongly increased its stability: after 28 days at 20°C, the residual activity was 25% of the initial

ISSN:0006-3592    

DOI:10.1002/bit.260281204

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe modification and principle of a novel heat flux calorimeter for thein situ, on‐line measurement of the heat generated during microbial growth is described. Data concerning the physical characterization of the calorimeter as a fermentor, including stability and sensitivity of the heat signal, are presented. The calorimeter has been successfully applied to the study of the aerobic batch culture ofEscherichia coliW on glucose under carbon and nitrogen limitation. A direct correlation between growth and heat evolution was obtained. Quantitative analysis of the data suggests that the new calorimetric technique could be used for monitoring growth and specific metabolic events, for convenient medium optimization, and as a basis for a novel fermentation process control syste

ISSN:0006-3592    

DOI:10.1002/bit.260281205

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

年代:1986

数据来源: WILEY

摘要:

AbstractA new immobilization technique suitable for coupled enzymes requiring cofactors was established. This is a droplet gel‐entrapping method in which many small droplets including the enzymes are fixed in the gel. The first emulsion was prepared by mixing of a solution containing thermostable malate dehydrogenase (MDH) and formate dehydrogenase (FDH) with benzene containing a surfactant. The first emulsion was added to a solution containing polyethyleneglycol(#4000)diacrylate andN,N′‐methylenebisacrylamide to prepare the second emulsion (w/o/w). After the second emulsion was gelled by addition of potassium persulfate and 3‐dimethylaminopropionitrile, the benzene was removed. The expressed MDH and FDH activities of the MDH–FDH immobilized gel were 7.1 and 13.9% of the initial activities, respectively. TheKmvalues of the gel were 0.60mMfor formate and 1.5μMfor NAD, respectively. TheKmfor formate and NAD were found to be extremely low. By using the column packed with 30 g gel having the MDH activity of 41.7 units and the FDH activity of 11.1 units, 13.8mMoxalacetate was completely converted to malate at 30°C. The malate production rate was not affected by the concentration of more than 50mMformate, more than 2mMoxalacetate, and more than 0.1 mMNAD, respectively. Long‐term malate production was demonstrated at 30°C by passing the substrate solution containing the two substrates and NAD through the column. The maximum conversion ratio (7.8%) was obtained at the fifth day, and 83% of maximum productivity was maintained even after 3 weeks. The expressed FDH activity at the fifth day was calculated to be 20.5% of the in

ISSN:0006-3592    

DOI:10.1002/bit.260281206

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

年代:1986

数据来源: WILEY

摘要:

AbstractA predictive model was developed to estimate the dewatering characteristics of waste‐activated sludges. This model utilizes the COD‐nitrogen ratio of the wastewater and the organic loading rate of the process to predict sludge filterability in terms of specific resistance. A completely mixed, continuous flow secondary treatment process with solids recycle was used for the cultivation of activated sludges. The sludge wasted from this process was used in Buchner funnel specific resistance determinations. The basic concepts involved in the development of the model were supported by sludge carbohydrate, protein, and surface charge d

ISSN:0006-3592    

DOI:10.1002/bit.260281207

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

年代:1986

数据来源: WILEY

摘要:

AbstractAn improved method is presented for estimating rejection coefficient‐molecular weight relationship of an ultrafiltration membrane for a polydisperse chain polymer. It is based on the basic idea using gel permeation chromatography originally developed by Cooper and Van Derveer. The method, in which peak spreading of an elution curve of the polymer was taken into consideration, is available for evaluating the relationship over a wide range of the molecular weight through only one experiment in analyses of the retentate and filtrat

ISSN:0006-3592    

DOI:10.1002/bit.260281208

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

年代:1986

数据来源: WILEY

摘要:

AbstractHydroxyurea, an inhibitor of DNA synthesis inSaccharomyces cerevisiae, has been applied in order to restrict growth of immobilized cells. For comparison, the influence of hydroxyurea on suspendedS. cerevisiaehas also been investigated. Recovery from DNA synthesis inhibition, indicated by measurements of cell growth rate, DNA content, and light scatter properties, occurred faster in immobilized cells than in the suspended yeast. Morphogenesis in both populations was arrested by hydroxyurea, and there was an accumulation of single immobilized and suspended cells with large buds. Synthesis of protein and RNA was not adversely affected in either cell type. The specific rate of ethanol production by immobilized cells increased by an average of 24%, while, for the suspended cells, specific ethanol productivity was up to three times higher. Glucose consumption rates for both cell types also increased under the influence of hydroxyurea. Immobilized cell ethanol yields were reduced by ca. 16% in the presence of hydroxyurea; suspended cell yields were lower by an average of 50%. Total polysaccharide content was reduced by 65% for suspended cells and increased 30% for immobilized cells after hydroxyurea treatment. The data evidence disturbance of the yeast cell cycle due to immobilization.

ISSN:0006-3592    

DOI:10.1002/bit.260281209

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

年代:1986

数据来源: WILEY

摘要:

AbstractExtracellular β‐xylosidase (1,4‐β‐D‐xylan xylohydrolase, EC 3.2.1.37) from culture filtrates ofNeurospora crassawas purified to homogeneity by preparative isoelectric focusing followed by gel electrophoresis. The molecular weight of the purified xylosidase was 83,000 D and theKmonp‐nitrophenyl‐β‐D‐xyloside was 0.047mM. The homogeneous xylanase (1,4‐β‐D‐xylan xylanohydrolase, EC 3.2.1.8) and β‐xylosidase showed differences in their mode of action towards xylooligosaccharides. The degree of hydrolysis ofD‐xylan by xylanase ofN. crassawas 18%. Supplementation of β‐xylosidase from the same organism resulted in 48% hydrolysis. The synergistic effect was more pronounced, with the hydrolysis of 68%, when a homogeneous preparation of β‐xylosidase fromSclerotium rolfsiiwas

ISSN:0006-3592    

DOI:10.1002/bit.260281210

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

年代:1986

数据来源: WILEY

摘要:

AbstractA carrier‐supported mycelial growth ofPenicillium chrysogenumwas applied to penicillin fermentation system using celite as a support material. Hyphal growth through the pore matrices of the material showed strong anchorages and provided highly stable biofilm growth. With bioparticles developed in such a manner, both cell growth and penicillin production were observed to increase significantly compared to the conventional dispersed filamentous cultures. Maximum values of specific penicillin production rate were found to be constant regardless of the growth form. A three‐phase fluidized‐bed fermentor was designed and tested for penicillin production using the bioparticles. Two modes of operation, semicontinuous and repeated fed batch, of the fermentor were tried. It was noted that the overgrowth of free mycelia and the development of fluffy loose bioparticles caused poor mixing and made the fermentor operation quite difficult. Control of the bioparticle size and the extension of production phase were therefore considered important to maintain the reactor productivity at a desired level. From the results of repeated fed‐batch operation it was found that the control of bioparticle size could be successfully achieved by phosphate‐limiting culture condition. Penicillin production under this condition was also observed to be maintained at a high level (about 80% of the maximum) for at leas

ISSN:0006-3592    

DOI:10.1002/bit.260281211

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

年代:1986

数据来源: WILEY