摘要:

AbstractThe feasibility of applying an adaptive control technique to a fermentation process is investigated. The nonlinear, time‐variant parameters of a fermentation process were estimated on‐line as a series of linearized describing matrices. The matrices were used to update a suboptimal feedback law which controlled the process in real time over the linear region. Experiments were performed on a small‐scale fully instrumented fermenter with the online, real‐time adaptive control package. Results are presented for both single‐ and multivariable control, and indicate successful control of yeast ce

ISSN:0006-3592    

DOI:10.1002/bit.260280502

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

年代:1986

数据来源: WILEY

摘要:

AbstractGrowth of a hybridoma culture, along with production of monoclonal antibody, was demonstrated over extended periods in polysulfone hollow fiber membrane modules. The molecular weight cutoffs of the membranes were 70,000, 50,000, and 100,000 daltons. The hybridoma cell line, designated 65/26, produced IgG (2b/κ) directed at mouse thymus cell surface antigen, TL.1. Cell growth occurred in the shell space of the reactor, using supplemented RPMI 1640 (20% fetal bovine serum) supplied from a separate reservoir vessel through the hollow fiber lumen. The reservoir contained 125 mL media, which was changed every 4 days. Concentrations of immunoglobulin were determined by an enzyme immunoassay (using protein A and alkaline phosphatase‐labeled antibody conjugate). For the 10K, 50K, and 100K hollow fiber membrane modules, the maximum IgG concentrations detected in the 2.5‐mL shell space were 47.5–80, 510, and 740 μg/mL, respectively. In the 125‐mL reservoir for the 100K hollow fiber membrane module, the IgG concentration was measured at 260 μg/mL These values compare with an IgG concentration of 1 μg/mL when grown in a standard tissue culture flask and 3.2–7.6 μg/mL when grown in 100 ml media in a spinner flask. In addition, 10K and 50K hollow fiber membrane modules were run in a mode that decreased the fetal bovine serum supplement with time. Differences between these systems suggest that it is possible to obtain high IgG accumulation rates, both during and after the exponential growth phase of the hybrid

ISSN:0006-3592    

DOI:10.1002/bit.260280503

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

年代:1986

数据来源: WILEY

摘要:

AbstractA nitrate control system has been devised for the maintenance of stable nitrate concentrations throughout fed‐batch fermentations ofCorynebacterium glutamicum.The feedback control system was based on the use of a nitrate‐ion‐selective electrode to directly monitor the nitrate levels in the fermentor and an automatic controller to activate a nitrate feed pump. The electrode which was used for controlling the nitrate level was stable through‐out the fermentation period. The apparent maximum specific growth rate, biomass production, protein production, biomass yields on glucose and nitrate, and amino acid production were all optimal at approximately 50mM

ISSN:0006-3592    

DOI:10.1002/bit.260280504

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

年代:1986

数据来源: WILEY

摘要:

AbstractExperiments were carried out to identify an efficient procedure for decreasing the amount of excess sludge in deep aeration columns. Incubation characteristics, especially cellular yield, are closely related to excess sludge, maximum specific growth rate, and chemical oxygen demand. They were measured here for the bacteriumPseudomonas aeruginosa, which tends to be predominant in sewage treatment, at a pressure remaining constant or periodically changing in the range of 1–6 atm (abs.). Cellular yields tended to decrease over 1–2 min pressure cycles; in steady operation they decreased considerably with increasing pressure or dissolved oxygen concentration. Maximum specific growth rates were moderately affected by periodic changes in pressure or dissolved oxygen concentration but markedly affected in the higher concentration range under steady operation. Substrate consumption rates on the other hand, were little affected in either case. The values of chemical oxygen demand ranged from 220 to 250 mg/L, and were thus nearly const

ISSN:0006-3592    

DOI:10.1002/bit.260280505

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe effect of dissolved carbon dioxide on the specific growth rate and the penicillin production rate ofPenicillium chrysogenumwas examined experimentally. The dissolved carbon dioxide was found to inhibit the specific growth rate and the penicillin production rate when the aerated submerged penicillin fermentation was exposed to influent gases of 12.6 and 20% carbon dioxide, respectively. Upon exposure to influent gases of 3 and 5% carbon dioxide, no pronounced metabolic inhibition was noted.

ISSN:0006-3592    

DOI:10.1002/bit.260280506

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

年代:1986

数据来源: WILEY

摘要:

AbstractBatch and continuous fermentations withClostridium thermoaceticum(ATCC 39073) using automatic pH control were conducted. The value of μmaxobtained from batch fermentation was about 0.14 h−1; acetate yield, which was both growth and non‐growth associated, was about 2 mole of acetic acid/mole of glucose, compared with a theoretical maximum value of 3. This low yield, compared with literature data, may be explained by glucose loss through a combination of degradation routes. Continuous fermentation could be sustained for 1600 h or more without contamination problems. Continuous fermentation at high dilution rates indicates that μmaxmay be well above 0.17 h−1when fresh feed medium is used. Acetate yields in continuous fermentation were about 77% of theoretical or 2.3 mole of acetic acid/mole of

ISSN:0006-3592    

DOI:10.1002/bit.260280507

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

年代:1986

数据来源: WILEY

摘要:

AbstractBoth the forward and backward reactions of xylose isomerase (Sweetzyme Q) with xylose and glucose as substrates have been studied in terms of kinetics and thermodynamics. The relationship between the two reactions can thus be determined. Much attention has been given to the reaction with xylose as substrate. The optimal conditions of the xylose reaction in terms of pH, buffer, metal ions, substrate concentration, temperature, and ionic strength have been determined. These findings did not differ much from those reported for the glucose reaction. Equilibrium constants for the aldose to ketose conversion were more favorable in the case of glucose. The results obtained with continuous isomerization of xylose in columns packed with either Sweetzyme Q or Taka‐Sweet were very similar to those obtained from batch isomerization processes. Particle size had a definite effect on reaction rate, which indicates that diffusion limitations do occur with the immobilized enzyme particles. Heat stability of Sweetzyme Q was good witht1/2of 118, 248, and 1200 h at 70, 55, and 40°C, respectively. A novel method for the separation of xylose–xylulose mixtures with water as eluant on a specially prepared Dowex 1 × 8 column was developed. This technique has the capability of producing pure xylulose for industrial or research applications. A writ for a patent regarding this technique is at present pre

ISSN:0006-3592    

DOI:10.1002/bit.260280508

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

年代:1986

数据来源: WILEY

摘要:

AbstractContinuous cultures ofSaccharomyces cerevisiaeare known to exhibit oscillatory behavior in the oxidative region. Important findings of a series of experiments conducted to identify the causes for initiation of and the means for elimination of oscillations in these cultures are reported in this paper. These oscillations are seen to be connected to the growth kinetics of the microorganism and are induced at very low glucose concentrations and at dissolved oxygen (DO) levels that are neither high nor low (DO values between 20 and 78% air saturation at a dilution rate of 0.2 h−1and pH of 5.5 at 30°C). The oscillatory behavior is encountered over a range of dilution rates (0.09–0.25 h−1at 30°C for pH = 5.5 and DO = 50% air saturation). The oscillations can be eliminated by raising the DO level above a critical value or by lowering the DO level below a critica

ISSN:0006-3592    

DOI:10.1002/bit.260280509

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

年代:1986

数据来源: WILEY

摘要:

AbstractAlcoholic fermentations of starch hydrolysate by two different yeast strains,Saccharomyces cerevisiae(var. Vinal) andSaccharomyces oviformis(IMAP 383), have been studied in batch runs. In order to evaluate the different inhibition phenomena due to both substrate and product, a new kinetic equation is suggested.

ISSN:0006-3592    

DOI:10.1002/bit.260280510

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe development of granular sludge in thermophilic (55°C) upflow anaerobic sludge blanket reactors was investigated. Acetate and a mixture of acetate and butyrate were used as substrates, serving as models for acidified waste‐waters. Granular sludge with eitherMethanothrixorMethanosarcinaas the predominant acetate utilizing methanogen was cultivated by allowing the loading rate to increase whenever the acetate concentration in the effluent dropped below 200 and 700 mg COD/L, respectively. The highest methane generation rates, up to 162 kg CH4‐COD/m3day, or 2.53 mole CH4/L day, were achieved at hydraulic retention times down to 21 min, with granules consisting ofMethanothrix.The formation ofMethanothrixgranules did not depend on the type of seed material, nor on the addition of inert support particles. The growth of granules proceeded rapidly with adapted seed material, even when the reactors were inoculated with low concentrations. With mesophilic seed materials growth of granules took much longer. ThermophilicMethanothrixgranules strongly resemble mesophilic granules of the “filamentous” type. Some factors governing the thermophilic granulation process are d

ISSN:0006-3592    

DOI:10.1002/bit.260280511

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

年代:1986

数据来源: WILEY