摘要:

AbstractWe carried out experiments designed to increase the rate of production of 4,4′‐dihydroxybiphenyl (biphenol) from biphenyl byAspergillus parasiticus. We show that 0.5 mg/ml biphenyl, the substrate for the reaction, significantly inhibits growth of the organism and that at 0.04 mg/ml, 2‐hydroxybiphenyl or 4‐hydroxybiphenyl (an intermediate of the reaction) strongly inhibit oxygen uptake, probably by inhibition of mitochondrial electron transport. Both factors may contribute to the low hydroxylation rates observed previously [J. H. Golbeck and J. C. Cox,Biotechnol. Bioeng.,26,434 (1984)]. We therefore adapted the organism to the presence of 0.08 mg/ml 2‐ and 4‐hydroxybiphenyl in the growth medium and found that cultures of adapted strains hydroxylated biphenyl at rates ca. three‐fold faster than control cultures. Once the fungal mycelia were grown, they could be recycled at least twice into fresh fermentation broth. Recycled organisms were capable of hydroxylating biphenyl more rapidly than cells in the primary fermentation culture and there was no lag period between introduction of biphenyl and the onset of hydroxylation. Cell recycle thus results in a considerable saving in carbon costs and ferm

ISSN:0006-3592    

DOI:10.1002/bit.260271002

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

年代:1985

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260271003

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe feasibility of the upflow anaerobic sludge bed (UASB) process for the treatment of potato starch wastewater at low ambient temperatures was demonstrated by operating two 5.65‐L reactors at 14°C and 20°C, respectively. The organic space loading rates achieved in these laboratory‐scale reactors were 3 kg COD/m3/day at 14°C and 4‐5 kg COD/m3/day at 20°C. The corresponding sludge loading rates were 0.12 kg COD/kg VSS/day at 14°C and 0.16−0.18 kg COD/kg VSS/day at 20°C.These findings are of considerable practical importance because application of anaerobic treatment at low ambient temperatures will lead to considerable savings in energy needed for operating the process. As compared with various other anaerobic wastewater treatment processes, a granular sludge upflow process represents one of the best options developed so far. Although the overall sludge yield under psychrophilic conditions is slightly higher than under optimal mesophilic conditions, this doesn't seriously hamper the operation of the process. The extra sludge yield, due to accumulation of slowly hydrolyzing substrate ingredients, was 4.75% of the COD input at 14°C and 1.22% of the COD

ISSN:0006-3592    

DOI:10.1002/bit.260271004

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

年代:1985

数据来源: WILEY

摘要:

AbstractAssessment was made to evaluate the effect of hydrogen peroxide pretreatment on the change of the structural features and the enzymatic hydrolysis of rice straw. Changes in the lignin content, weight loss, accessibility for Cadoxen, water holding capacity, and crystallinity of straw were measured during pretreatment to express the modification of the lignocellulosic structure of straw. The rates and the extents of enzymatic hydrolysis, cellulase adsorption, and cellobiose accumulation in the initial stage of hydrolysis were determined to study the pretreatment effect on hydrolysis. Pretreatment at 60°C for 5 h in a solution with 1% (w/w) H2O2and NaOH resulted in 60% delignification, 40% weight loss, a fivefold increase in the accessibility for Cadoxen, an one times increase in the water‐holding capacity, and only a slight decrease in crystallinity as compared with that of the untreated straw. Improvement on the pretreatment effect could be made by increasing the initial alkalinity and the pretreatment temperature of hydrogen peroxide solution. A saturated improvement on the structural features was found when the weight ratio of hydrogen peroxide to straw was above 0.25 g H2O2/g straw in an alkaline H2O2solution with 1% (w/w) NaOH at 32°C. The initial rates and extents of hydrolysis, cellulase adsorption, and cellobiose accumulation in hydrolysis were enhanced in accordance with the improved structural features of straw pretreated. A four times increase in the extent of the enzymatic hydrolysis of straw for 24 h was attributed to the alkaline hydrogen peroxide pretreatm

ISSN:0006-3592    

DOI:10.1002/bit.260271005

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

年代:1985

数据来源: WILEY

摘要:

AbstractSurface area has been proposed as a major factor determining the extent of enzymatic hydrolysis of cellulose. We used cornstalk residue (CR) and Solka Floc BW‐300 (SF) as substrates and NaOH (a cellulose swelling agent) and iron sodium tartrate (FeTNa, intercolates between cellulose microfibrils) as pretreatments to study the effect of surface area on extent of fermentation. Micropore sizes (8‐130 Å) were determined by a solute exclusion technique using glucose, cellobiose, and polyethylene glycols as molecular probes. The pore size distributions follow the logistic model function:I=a/[1+exp(b−cX)] whereIis pore volume;X= logD;Dis the molecular probe diameter; anda,b, andcare constants. The pore volumes of CR (1.9 mL/g) and SF (1.6 mL/g) are increased to 2.1 mL/g by pretreatment with NaOH. Pretreatment of SF with NaOH and cornstalk residue with FeTNa caused an upward shift in the pore size distribution. Fermentation of untreated CR by rumen microbes resulted in a 46% loss of dry matter while increasing the internal pore size and decreasing the pore volume to 0.9 mL/g. Fermentation of NaOH pretreated CR resulted in a 73% loss of dry matter with little change in pore size, total pore volume, or fiber composition. Fiber analysis indicated that selective utilization of hemicellulose over cellulose in both fermentations was small. The data show that: (1) removal of hemicellulose and lignin increases dry matter disappearance upon fermentation of the remaining material; (2) relative to the size of bacterial cellulases (40‐160 Å), the pretreatments have little effect on increasing accessibility of surface internal to the cellulose particles; and (3) the micropore changes caused by NaOH or FeTNa treatment do not explain the enchanced fermentation obtained for treated cornstalk residue. These observations infer that external or macropore surface properties may be a significant factor in determining the extent of utilization of the solid substrates by cellulolytic micro

ISSN:0006-3592    

DOI:10.1002/bit.260271006

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

年代:1985

数据来源: WILEY

摘要:

AbstractRecovery of proteins frequently involves a precipitation step in which ease of recovery of the solid protein depends on the size and density of the solid particles. The solid particles are actually aggregates of much smaller primary particles. In this work, possible influences on the aggregates of primary particle properties are postulated. The role of precipitation conditions during precipitation of soy protein with acid or CaCl2is determined by measurement of zeta potential and size distribution. Results are consistent with a nucleation/growth model for determination of size. There is indirect evidence that fractionation occurs at the primary particle level, although the particles are homogeneous at the aggregate level.

ISSN:0006-3592    

DOI:10.1002/bit.260271007

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

年代:1985

数据来源: WILEY

摘要:

AbstractProduction of cellulase using solid culture systems ofTrichoderma reeseiQM9414 andSporotrichum cellulophilumon wheat bran was studied. By using moisture‐controlled solid culture equipment, the effect of water content of wheat bran on cell growth and cellulase production was investigated. Cellular biomass grown on solid substrate was estimated by measuring oxygen consumption rate and glucosamine content of the cells. These parameters were shown to have a good linear correlation with the specific growth rate. This reliable method of estimating the cell growth rate enabled us to simulate the enzyme production in a solid culture system by means of multiple linear regression analysis which takes into account of the water content, cell mass, and the oxygen consumption rate as variables. The cell growth and cellulase production were maximized at different water content of the medium. A high water content, 57% forT. reeseiand 70% forS. cellulophilum, favored mycelial growth, while the maximum cellulase activity was obtained at a lower water content such as 50% for both fungi. It was observed that cellulase production byT. reeseidepended on the culture conditions that support the optimal growth rate for the maximum enzyme productio

ISSN:0006-3592    

DOI:10.1002/bit.260271008

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

年代:1985

数据来源: WILEY

摘要:

AbstractTrypsin and chymotrypsin were separated from porcine pancreas extract by continuous pH‐parametric pumping. CHOM (chicken ovomucoid) was convalently bound to laboratory‐prepared crab chitin with glutaraldehyde to form an affinity adsorbent of trypsin. The pH levels of top and bottom feeds were 8.0 and 2.5, respectively. Similar inhibitor, DKOM (duck ovomucoid), and pH levels 8.0 and 2.0 for top and bottom feeds, respectively, were used for separation and purification of chymotrypsin. ε‐Amino caproyl‐D‐tryptophan methyl ester was coupled to chitosan to form an affinity adsorbent for stem bromelain. The pH levels were 8.7 and 3.0. Separation continued fairly well with high yield, e.g., 95% recovery of trypsin after continuous pumping of 10 cycles. Optimum operational conditions for concentration and purification of these enzymes were investigated. The results showed that the continuous pH‐parametric pumping coupled with affinity chromatography is effective for concentration and purificatio

ISSN:0006-3592    

DOI:10.1002/bit.260271009

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe advantages of retrofitting anin situsoluble enzyme batch process to an immobilized enzyme continuous process are contrasted against the disadvantages by means of a dimensionless feasibility/optimization analysis. The general analysis is applied to the case of an adsorbed enzyme system where a maximum in activity occurs with respect to loading. For this case, a minimum in the ratio of enzyme‐carrier complex working lifetime toin situbatch process time and a maximum in the cost difference between thein situand retrofit processes occurs with respect to loading and retrofit process conversion. For the maximization of cost difference, the analysis also suggests a criterion that can be used to determine whether the values for optimal loading and retrofit conversion will result in the retrofit being economically feasible. When infeasibility occurs, qualitative sensitivity analysis for a variety of situations points out whether a catalyst or process modification will improve feasibility the most. Apart from forming the basis for an iterative retrofit process design algorithm, the modeling approach's ability to specify optimal values of catalyst properties such as loading lends itself to defining process‐specific, catalyst design “targets” would be useful for those developing immobilized enzyme preparation methodology and those investigating enzyme–carrier int

ISSN:0006-3592    

DOI:10.1002/bit.260271010

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

年代:1985

数据来源: WILEY

摘要:

AbstractFor the large‐scale operation of microcarrier culture to be successful, a technically feasible method for sequential inoculation is essential. Using human foreskin fibroblasts, FS‐4, we have achieved this by detaching cells viably from microcarriers employing a selection pH trypsinization technique. Cells thus detached are able to reattach to microcarriers and grow normally after subsequent reinoculation into new cultures. However, after reinoculation cells attach to new microcarriers at a higher rate than to used microcarriers on which cells have previously grown. The effect of this differential cell attachment was analyzed and overcome by employing a low inoculum concentration. FS‐4 cells could thus be serially propagated on microcarriers and subsequently used for β‐interferon production. This technique has also been applied to the cultivation of a monkey kidney cell line, Vero. We have also shown that Vero cells directly inoculated from a seed microcarrier culture could be used for virus pr

ISSN:0006-3592    

DOI:10.1002/bit.260271011

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

年代:1985

数据来源: WILEY