摘要:

AbstractUnder certain simplifying hypotheses, a chemostat in which one microbial population feeds on another can be described by a system of three ordinary differential equations. A study is conducted to find which features of the equations are the most important to the dynamics of the system; it is found that the main influence comes from the from the particular form of the specific growth rate of the feeding population. Some conditions are derived that relate the form of the specific growth rate of the feeding population to the dynamic behaviour of the system.

ISSN:0006-3592    

DOI:10.1002/bit.260271102

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe diffusion coefficients for glucose and oxygen through the microbial aggregate were measured, and then the dependency on the biochemical factors was investigated. Kinetic and diffusion studies were carried out experimentally for this purpose. Both coefficients were found to be dependent not only on the bacteria concentration but also on the C/N ratio of microbial aggregate at the high bacteria concentration, when the temperature was 20 ± 2°C. On the other hand, these values were considered to be independent of both factors at the low bacteria concentration, when the temperature was 20 ± 2°C. In other words, both coefficients were approximately 86–95% of the values in water at the high bacteria concentration and nearly 100% of the values in water at the low bacteria concentration. It was also found that they were dependent on the temper

ISSN:0006-3592    

DOI:10.1002/bit.260271103

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe initial rate of hydrolysis of six commercially available native (type l) celluloses was determined for the crude cellulase complexes of the thermophilic anaerobic bacteriumC. thermocellumand the mesophilic fungusT. reesei. These rates were then compared with certain physical features of the substrates in an attempt to determine the role of cellulose structure in its degradability. Within the substrate series tested, theClostridiumsystem showed a greater relative range in rate of enzymatic hydrolysis than did theTrichodermasystem. Average correlation coefficients for the kinetic rates from bacterial and fungal cellulases, respectively, and the following physical parameters were obtained: relative crystallinity index (RCl) from acid hydrolysis, −0.61 and −0.85; RCl from x‐ray diffraction, −0.75 and −0.89; accessibility to formylation at 4°C, + 0.49 and +0.60; nonaccessibility to formylation at 65°C, −0.40 and −0.73; fiber saturation point, + 0.83 and + 0.85. Kinetic and pore volume distribution data suggest that the rate‐limiting components of both the bacterial and fungal cellulase systems are of similar size, approximately 43

ISSN:0006-3592    

DOI:10.1002/bit.260271104

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe possibility of obtaining immobilized horseradish peroxidase (HRP) materials withK′mvalues close to that of the native enzyme, but with good thermal stability, was investigated. The photochemical reaction was used as the immobilization methodology. Temperature and catalyst concentration were found to be the main parameters able to control the immobilization reaction mechanism more than type of functional monomer, polymer–matrix, and enzyme–polymer ratios. By carrying out the immobilization reaction at 35°C and using either bisacryloylpiperazine (BAP) or hexhydro‐1,3,5‐triacryloyl‐s‐triazine (HTsT) as the functional monomer, materials with a good thermal stabilization (the retained activity after 240 min at 60°C was between 65–25%) as well as kinetic constants (0.6–0.8 × 10−4M) similar to that of the free enzyme (0.57 × 10−4M) were obtained. Since lowK′mvalues were obtained also using a high polymer content (pBAP copolymers, 25%; pHTsT copolymers, 30%) and neither limitation to substrate diffusion nor a reduction of the enzyme mobility was found, the enzyme should be linked to the matrix during the last steps of monomer polymerization, and it should have an external disposition

ISSN:0006-3592    

DOI:10.1002/bit.260271105

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

年代:1985

数据来源: WILEY

摘要:

AbstractA model is proposed for the denaturation of enzymes based on heterogeneous enzyme subpopulations with nonuniform initial activities and nonzero final activities. The more frequently used simple first‐order deactivation model is a special case of the model corresponding to the standard deviation of Gaussian distribution of activation energies approaching zero. Parametric studies made with the model are capable of simulating the reported trends in experimental data on the thermal profile and activity time behavior of native as well as modified enzymes with a minimum number of adjustable parameters. The model predictions are found to be in good agreement with data reported in the literatur

ISSN:0006-3592    

DOI:10.1002/bit.260271106

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

年代:1985

数据来源: WILEY

摘要:

AbstractTrace concentrations of chlorinated benzenes and chlorinated aliphatics were biotransformed by acetate‐supported biofilms, the former under aerobic conditions and the latter under methanogenic conditions. The rates of transformation of the halogenated organic compounds (secondary substrates) differed from that of acetate, the primary substrate; some were higher, some were lower, and some were similar. Factors affecting the relative rates of utilization in multisubstrate systems are not know

ISSN:0006-3592    

DOI:10.1002/bit.260271107

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.260271108

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.260271109

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.260271110

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.260271111

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

年代:1985

数据来源: WILEY