摘要:

AbstractA simple adaptive control algorithm, for which theoretical stability and convergence properties had been previously demonstrated, has been successfully implemented on a biomethanation pilot reactor. The methane digester, operated in the CSTR mode was submitted to a shock load, and successfully computer controlled during the subsequent transitory state.

ISSN:0006-3592    

DOI:10.1002/bit.260310402

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe influence of temperature, pH, and substrate and product concentrations on the oxidation rate of ferrous iron by biofilm ofThiobacillus ferrooxidanswas determined. The experiments were performed in an inverse fluidized‐bed biofilm reactor in which the biofilm thickness was kept constant at 80 μm. Oxygen concentration and diffusion through the biofilm did not limit the oxidation rate. The oxidation rate was almost unaffected by temperature between 13 and 38°C, pH between 1.3 and 2.2, ferric iron concentration up to 14 g/L, or ferrous iron concentration from 4 to 13 g/L. The kinetics of the process was described by the Monod equation with respect to the mass of the biofilm and with ferrous ions as the limiting substr

ISSN:0006-3592    

DOI:10.1002/bit.260310403

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

年代:1988

数据来源: WILEY

摘要:

AbstractA total of 58 yeast strains from 12 genera were assayed for their ability to grow and ferment carbohydrates in standard Durham tube test at 40, 43, and 46°C. Based on the kinetic parameters for glucose fermentation in shaken flask cultures, the strainFabospora fragilisCCY51‐1‐1 was chosen for further studies. It reached about 56.0 and 35.0 g ethanol/L from ∼140 g glucose/L at 43 and 46°C in less than 48 h, respectively.Trichoderma reeseicellulase preparation (400 FPU/L) had not distinct effect on the ethanol yield and biomass production by the selected strain in the first 12 h fermentation at 46°C. Later a negligible decrease in both yields was observed. It was found thatFabospora fragilisdid not grow or produce ethanol at 46°C as tho initial ethanol concentration overca

ISSN:0006-3592    

DOI:10.1002/bit.260310404

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

年代:1988

数据来源: WILEY

摘要:

AbstractA segregated model of multicopy plasmid propagation has been formulated which incorporates plasmid replication and partition functions, as well as the effect of plasmid presence on host growth rate. Growth of plasmid‐free cells in selective medium is explicitly analyzed. The model parameters can be determined from experimentally measurable quantities. Propagation of a recombinant multicopy plasmid in the yeastSaccharomyces cerevisiaeis analyzed using this mode

ISSN:0006-3592    

DOI:10.1002/bit.260310405

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe objective of this work was to relate macroscopically measurable on‐line fermentation parameters such as dissolved oxygen, off‐gas oxygen and carbon dioxide, and cell mass, to the controlled production of key intracellular enzymes under carbon limited conditions. Both batch and perturbed batch aerobic fermentations were performed using two different strains ofEscherichia coli, with glucose and lactose as the sole carbon sources. The two strains differed from each other only in thelac operonregion of their genome. The parent strain,E. coli3000, was inducible for the enzyme β‐galactosidase. The other strain,E. coli3300, was a constitutive mutant in the production of β‐galactosidase. In all experiments, off‐line assays of sugars and β‐galactosidase activity were performed. It was observed that there is a clear relationship between the macroscopic on‐line measurements, dissolved oxygen tension, carbon dioxide evolution rate and oxygen uptake rate, and the microscopic control phenomena of catabolite repression, catabolite inhibition, and in

ISSN:0006-3592    

DOI:10.1002/bit.260310406

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

年代:1988

数据来源: WILEY

摘要:

AbstractA combination of ionic strength reduction and diafiltration ofTrichoderma reeseicellulate complex through a hollow fiber apparatus of 5000 molecular weight (MW) cutoff and subsequent passage of filtrate over a Spherogel‐TSK 3000‐SW column provided extracts that had the ability to generate microfibrils in filter paper and to disrupt filter paper and corn leaf tissue. Milligram quantities of material obtained from these extracts released small amounts of soluble carbohydrate from filter paper, required ferric iron for increased activity, and contained amino acids. Short fiber formation and disruption of filter paper during interaction with these extracts was enhanced by prior acid treatment and eliminated by prior base treatment. The amount of soluble carbohydrate hydrolyzed in 24 h from filter paper by whole cellulase complex was not changed by first disrupting the substrate with the extra

ISSN:0006-3592    

DOI:10.1002/bit.260310407

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

年代:1988

数据来源: WILEY

摘要:

AbstractBatch experiments were conducted to examine the effects of several substrate analogs on the degradation of pentachlorophenol by an enrichment culture of pentachlorophenol‐utilizing bacteria. The presence of substrate analogs which were unable to serve as a carbon source for growth of the culture (e.g., 3,5,6,‐trichloro‐2‐pyridinol, 2,4‐dichlorophenoxyacetic acid) decreased the rate of pentachlorophenol degradation. The presence of a utilizable substrate analog (e.g., phenol, 2,4,5‐trichlorophenol) also inhibited the initial rate of pentachlorophenol degradation; however, the overall removal rate was accelerated due to an increase in cell mass concentration as a result of simultaneous growth on both substrates. These effects were shown to be predicted by a mathematical model based on a modified Monod equation. Kinetic parameters obtained from the results of laboratory studies can be used for further process analysis to define the optimal conditions for the biological treatment of complex mixtures of phenoli

ISSN:0006-3592    

DOI:10.1002/bit.260310408

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

年代:1988

数据来源: WILEY

摘要:

AbstractPhotobioreactor design and operation are discussed in terms of mixing, carbon utilization, and the accumulation of photosynthetically produced oxygen. The open raceway pond is the primary type of reactor considered; however small diameter (1–5 cm) horizontal glass tubular reactors are compared to ponds in several respects. These are representative of the diversity in photobioreactor design: low capital cost, open systems and high capital cost, closed systems. Two 100‐m2raceways were operated to provide input data and to validate analytical results. With a planktonicChlorellasp., no significant difference in productivity was noted between one pond mixed at 30 cm/s and another mixed from 1 to 30 cm/s. Thus, power consumption or CO2outgassing limits maximal mixing velocities. Mixing power inputs measured in 100‐m2ponds agreed fairly well with those calculated by the use of Manning's equation. A typically configured tubular reactor flowing full (1 cm diameter, 30 cm/s) consumes 10 times as much energy as a typical pond (20 cm deep flowing at 20 cm/s). Tubular reactors that flow only partially full would be limited by large hydraulic head losses to very short sections (as little as 2 m length at 30 cm/s flow) or very low flow velocities. Open ponds have greater CO2storage capacity than tubular reactors because of their greater culture volume per square meter (100–300 L/m2vs. 8–40 L/m2for 1–5‐cm tubes). However, after recarbonation, open ponds tend to desorb CO2to the atmosphere. Thus ponds must be operated at higher pH and lower alkalinity than would be possible with tubular reactors if cost of carbon is a constraint. The mass transfer coefficient,KL, for CO2release through the surface of a 100‐m2pond was determined to be 0.10 m/h. Oxygen buildup would be a serious problem with any enclosed reactor, especially small‐diameter tubes. At maximal rates of photosynthesis, a 1‐cm tubular reactor would accumulate 8–10 mg O2/L/min. This may result in concentrations of oxygen reaching 100 mg/L, even with very frequent gas exchange. In an open pond, dissolved oxygen rises much more slowly as a consequence of the much greater volume per unit surface area and the outgassing of oxygen to the atmosphere. The maximum concentration of dissolved oxygen is typically 25–40 mg/L. The major advantage of enclosed reactors lies in the potential for aseptic operation, a product value which justifies the expense. For most products of algal mass cultivation, open ponds are the only feasible photobioreactor design capable of meeting the economic and operating requirements of such systems, provided desirable sp

ISSN:0006-3592    

DOI:10.1002/bit.260310409

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

年代:1988

数据来源: WILEY

摘要:

AbstractNeedle‐punch polyester was shown to be an effective support material for the immobilization ofTrichoderma reeseiRut C30. When used as a resident inoculum for a batch process, the immobilizedTrichodermawas very stable and resulted in a reduced rate of biomass generation in the bulk liquid phase as compared to cultures inoculated with free mycelium. Fed‐batch fermentations with the immobilizedTrichodermaproduced ca. 80% of the activity of those using free cells; however, the activity was more stable and the crude enzyme broth produced had a greatly reduced biomass concentrat

ISSN:0006-3592    

DOI:10.1002/bit.260310410

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe lipase produced byPseudomonas fluorescensbiotype I was selected for hydrolyzing beef tallow at 50–70°C to more than 90% of reaction ratio. Using an amount of lipase sufficient to reach equilibrium, the final reaction ratio was decreased with increasing temperature and the apparent enthalpy of beef tallow hydrolysis obtained by the final reaction ratio was −1.93 × 104cal/mol, and the final reaction ratio also decreased with increasing substrate concentration. The rising time, which is the reaction time up to one‐half of the final reaction ratio, decreased remarkably with increasing temperature, and was closely related to the value of the maximum velocity by the Michaelis constant of this lipase. The final reaction ratio increased with increasing lipase amount up to equilibrium. Increasing the lipase above the amount required to reach equilibrium caused a decrease in the rising time. The feasibility of using parameters obtained by a hyperbolic simulation of the progress curve is di

ISSN:0006-3592    

DOI:10.1002/bit.260310411

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

年代:1988

数据来源: WILEY