摘要:

AbstractTreatment of a wide variety of lignocellulosic biomass with gaseous ozone results in greatly enhanced susceptibility to cellulase enzyme hydrolysis and to digestion by rumen microorganisms so that it can be used as ruminant animal feed or for the production of glucose via enzymatic hydrolysis. By use of appropriate reaction conditions a useful degree of such pretreatment may be obtained in 1–2 h contact time with an ozone consumption of ca. 4–6% of the dry weight of the biom

ISSN:0006-3592    

DOI:10.1002/bit.260260112

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe influence of growth rate onEscherichia coliplasmid content and expression of a cloned‐gene product has been described by a mathematical model based upon the molecular mechanism of λdv plasmid replication and known relationships between growth rate and transcription and translation activities of the host cell. The model simulates correctly decreases in plasmid content with increasing growth rate as observed experimentally forpBR322, NR1, R1, and Col E1 plasmids. A maximum with respect to growth rate in intracellular product accumulation is indicated by the model, as is a transient overshoot in product concentration following a shift from smaller to larger growth rate. Available data, although very limited, show the same trends. These results, obtained without parameter or kinetic form adjustments or manipulation, clearly illustrate the advantages of kinetic descriptions of recombinant systems based upon the pertinent molecular mechanis

ISSN:0006-3592    

DOI:10.1002/bit.260260113

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

年代:1984

数据来源: WILEY

摘要:

AbstractProline excretion from proline overproducing strains ofE. coliK12 has been studied as a model chemical production system. We have isolated proline overproducing mutants ofE. coliand have shown that uncontrolled synthesis is not sufficient to cause excretion of this amino acid. An episomal mutation causing proline over production has been introduced into a series of otherwise isogenic strains that bear well defined, chromosomal lesions affecting the active uptake and catabolism ofL‐proline. A syntropism test reveals thatL‐proline is excreted by overproducing strains only if transport and/or catabolism are impaired. Dansyl derivatization and chromatographic analysis of culture supernatants shows that proline is the only amino acid excreted. Batch cultures of an excreting strain in an amino acid production medium yield culture supernatants containing 1 g proline/L, whereas no proline is detectable in supernatants derived from cultures of an overproducing strain with normal transport and catabolic activities. These data reveal that genetic lesions eliminating active uptake can be used to specifically enhance metabolite excret

ISSN:0006-3592    

DOI:10.1002/bit.260260114

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

年代:1984

数据来源: WILEY

摘要:

AbstractAs part of an investigation into the use of biological nitrogen fixation for fertilizer ammonia production, continuous culture studies of respiration and nitrogen fixation in the aerobic bacteriaAzotobacter vinelandiiunder oxygen‐limited conditions were conducted. Respiration and growth rates followed Monod forms with respect to dissolved oxygen concentration. However, specific nitrogen fixation rate and nitrogenase activity exhibited maximum values at dissolved oxygen concentrations of ca. 0.02 mM(10% of air saturation). These results suggest careful control of oxygen in the environment is necessary to optimize fixed nitrogen production by this organis

ISSN:0006-3592    

DOI:10.1002/bit.260260115

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

年代:1984

数据来源: WILEY

摘要:

AbstractContinuous culture studies ofAzotobacter vinelandiicells immobilized by ionic adsorption to Cellex E anion exchange resin were conducted under oxygen‐limited conditions for comparison to free‐cell cultures. Immobilization had little effect upon the specific respiration and sucrose consumption rates as compared to free cells. However, maxima in specific nitrogen fixation rate and nitrogenase activity as a function of dissolved oxygen occurred at a C O 2value of approximately 0.005 mMas opposed to 0.02 mMfor free cells. Further, in contrast to free‐cell culture, most of the fixed nitrogen appeared in the medium rather than within intact cells. There were strong indications that reproduction of bound cells often resulted in cell lysis accounting for the fixed nitrogen content in

ISSN:0006-3592    

DOI:10.1002/bit.260260116

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe leaching of pyrite sulfur from coal employingThiobacillus Ferrooxidanswas studied in a continuous stirred tank reactor at a variety of dilution rates (0.02–0.11 h−1) and coal surface areas (0.25–1.0 m2/mL). The bacterial leaching rate was found to increase with increasing coal surface area concentration and increasing dilution rate. The bacterial concentration on the coal surface was related to the bacterial concentration in solution by a irreversible second‐order (of the second kind) kinetic equation. The concentration of bacteria on the coal in all experiments was the concentration at saturation. Step changes in the coal concentration were observed to result in dramatic declines in bacterial concentration in solution. A bacterial mass balance model was employed to calculate the specific growth rate on the solid which was observed to increase with increasing diluti

ISSN:0006-3592    

DOI:10.1002/bit.260260117

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

年代:1984

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260260118

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

年代:1984

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260260119

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

年代:1984

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260260101

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

年代:1984

数据来源: WILEY