摘要:

AbstractProteus vulgarisis shown to take up nicotinic acid in the early stage of growth in amounts greater than needed for growth. The time variation of the specific nicotinic acid content of the cells, calculated by dividing the amount of nicotinic acid taken up from the liquid medium by the mass of cells present at that time, is interpreted to define two parameters, the maximum specific nicotinic acid content,f1, and the minimum content required for growth,f2The difference,E, between these parameters is the specific nicotinic acid content capable of supporting growth for three doublings after depletion of nicotinic acid from the medium. A kinetic model for the system is developed based upon two stages of growth, a stage in which the cells accumulate from the medium their maximum nicotinic acid content, and a stage in the nicotinic acid‐depleted medium in which cell growth occurs at the expense of the cell‐bound nicotinic a

ISSN:0006-3592    

DOI:10.1002/bit.260290102

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe production ofLeuconostoc mesenteroidessucrose phosphorylase has been studied in 10‐ and 20‐L batch fermentations. A fermentation medium was devised combining rapid growth, high cell yield, and high enzyme levels. Overall fermentation dynamics and enzyme fermentation patterns are elucidated here in detail. Sucrose is phosphorolyzed into fructose and glucose‐1‐phosphate (G‐1‐P) with G‐1‐P preferentially utilized (thus saving ATP). Subsequently, fructose is gradually metabolized and is also converted to mannitol. Invertase activity is absent. Sucrose phosphorylase is formed transitorily with peak levels toward the end of active growth; a sharp decline in enzyme activity occurs upon further fermentation. The moment of cell (enzyme) harvest is thus critical in view of obtaining active cell or enzyme preparations for sucrose phosphorolysis. Microaerophilic and strictly anaerobic fermentations displayed no appreciable difference in sucrose phosphorylase formation profile. The enzyme is intracellularly located. It is constitutively formed in the absence of sucrose, contrary to that ofPseudomonasspecies; other disaccharide phosphorylases

ISSN:0006-3592    

DOI:10.1002/bit.260290103

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

年代:1987

数据来源: WILEY

摘要:

AbstractThis article aims at deriving kinetic models for the RBS reactor operating with and without cell porous support. Since derivation of the kinetic equations from the Monod model is very complex, an empirical derivation from experimental data of continuous alcohol fermentations is used in this work.

ISSN:0006-3592    

DOI:10.1002/bit.260290104

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe effect of acoustic conditioning on the particle size distribution of isoelectric and calcium‐ion‐precipitated soya protein has been examined in low‐residence‐time chambers. In a previous study a beat frequency of 5 Hz obtained using a dual‐source system of opposing vibrators was determined as giving optimal improvement in particle‐settling characteristics for isoelectric soya protein precipitate. In this study the effect of amplitude of vibration, a measure of acoustic power input, and residence time of acoustic conditioning has been examined.Acoustic power input changed the flow pattern in the conditioning chamber from laminar streamline flow to a well‐mixed, turbulent pattern. Such a mixing effect promoted the rapid aggregation of fine particles, a process that was modeled on the basis of orthokinetically controlled collisions. The rate of removal of fine particles due to acoustic conditioning was shown to be proportional to a mixing effect that was releated to the acoustic power dissipated per unit volume.The consequences of fine‐particle aggregation on the centrifugal recovery of the precipitat

ISSN:0006-3592    

DOI:10.1002/bit.260290105

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

年代:1987

数据来源: WILEY

摘要:

AbstractTylosin‐producingStreptomyces fradiaewas cultured on a synthetic medium with a high glutamate–glucose ratio. Tylosin batch fermentations with this medium were characterized by a high initial specific production rate of tylosin (qtylosin, mg/g h) that decreased as the fermentation progressed. Continuous feeding of glutamate, glucose, and methyloleate at a constant feed rate initiated during the period of highqtylosinhad been shown to produce some increase in tylosin productivity. By using a cyclic feeding strategy, it was possible to increase tylosin productivity further. Tylosin fed‐batch fermentations with glutamate and glucose being fed to the culture in cyclic square‐wave profiles with methyloleate in excess showed several‐fold increase in finalqtylosinand tylosin titers. By varying cycle amplitudes and period of the substrates, it was found that maximum tylosin productivity occurred when the glutamate cycle amplitude was 600 mg/L and that of glucose was 42.5 mg/L per cycle period of 24 h. With these cycle amplitudes of glutamate and glucose, the tylosin cyclic fed‐batch culture also showed high cellular uptake of methyloleate. Decreasing or increasing glucose cycle amplitude at fixed glutamate amplitude lowered tylosin production, and no further stimulation of tylosin synthesis was observed when α‐ketoglutarate was supplemented to the cyclic substrate feeds. Under optimum cyclic conditions it was possible to maintain linear tylosin accretion and a constant value ofqtylo

ISSN:0006-3592    

DOI:10.1002/bit.260290106

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

年代:1987

数据来源: WILEY

摘要:

AbstractChanges of pH and sulfate concentration in high‐sulfur coal refuse slurries are used as measurements of microbial pyrite oxidation in the laboratory. Sodium lauryl sulfate (SLS), alkylbenzene sulfonate (ABS), benzoic acid (BZ) and combinations of SLS plus BZ and ABS plus BZ effectively inhibited formation of sulfate and acid when added in concentrations greater than 50 mg/L to inoculated 20 or 30% coal refuse slurries. Here 25 mg/L concentrations of SLS, ABS, and ABS + BZ stimulated acid production. Formic, hexanoic, oxalic, propionic, and pyruvic acids at 0.1% concentrations were also effective inhibitors. Four different lignin sulfonates were only slightly effective inhibitors at 0.1% concentrations. It was concluded that acid formation resulting from microbial oxidation in high‐sulfur coal refuse can be inhibi

ISSN:0006-3592    

DOI:10.1002/bit.260290107

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe combination of sodium lauryl sulfate and benzoic acid effectively inhibits iron‐ and sulfur‐oxidizing bacteria in coal refuse and prevents the conversion of iron pyrite to sulfate, ferric iron, and sulfuric acid, thereby significantly reducing the formation of acidic drainage from coal refuse. The inhibitors were effective in a concentration of 1.1 mg/kg refuse, and data indicate that the SLS was in excess of the concentration required. The treatment was compatible with the use of lime for neutralization of acid present prior to inhibition of its format

ISSN:0006-3592    

DOI:10.1002/bit.260290108

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe dynamic behavior of the Ribulose Monophosphate‐typeMethylomonasL3 in continuous cultures was studied, using methanol pulses to induce fast transients in steady‐state cultures of single (methanol) and mixed (methanol plus formaldehyde) substrates. In several experiments, the methanol‐uptake rate (MUR) profiles displayed negative MUR values for a time period following the methanol pulse, and significant amounts of methanol disappeared immediately following the pulse. These phenomena suggested the accumulation of methanol in the cells upon pulsing, apparently due to an active transport system. Accordingly, and in order to estimate the potential of the transport system for methanol accumulation, accumulation profiles were calculated for several pulse experiments. The calculations are based on a methanol balance and experimentally determined values of the cell volume and the true transient biomass yields. It is calculated that methanol accumulates up to 200‐fold to very high intracellular concentrations. The accumulation is calculated to be much higher in single‐ (methanol) substrate cultures of low dilution rate than in cultures of high dilution rate or of mixed substrates. The specific growth rate immediately following the methanol pulse decreased in single‐substrate cultures and increased in mixed‐substrate ones. The biomass yield decreased after the methanol addition in all experiments; however, the drop was less severe in the mixed‐substrate experiments. It is also suggested that formaldehyde as a methanol cosubstrate may be an effective means of providing more stable biomass yields and growth rates in reactors with imperfect mixing, and of protecting the reactor against accidentally induced methan

ISSN:0006-3592    

DOI:10.1002/bit.260290109

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

年代:1987

数据来源: WILEY

摘要:

AbstractHigh methanol concentrations have a negative effect on the growth rate and the biomass yield of growth transients induced by methanol pulses in continuous cultures ofMethylomonasL3. The physiological basis of this effect is investigated by measuring the effect of the methanol pulse on the cell energy charge (EC) and ATP, ADP, and AMP concentrations, and by comparing the results of the pulse transients against an unstructured model. The methanol pulse is shown to lead to increased values of the cell EC and ATP concentration, and thus, inhibition and reduced availability of biosynthetic energy are excluded as causes of inhibition. When the biomass and methanol profiles of the transient experiments are compared in phase‐plane diagrams against computer simulations based on the model, satisfactory agreement between experimental data and model predictions is found in single‐substrate, high‐dilution‐rate experiments. Conversely, poor agreement between experimental data and simulation results indicates a more severe growth inhibition than the model predicts at low dilution rates and a less severe one in mixed‐substrate experiments. Based on these findings and other relevant physiological information, we propose that the large variations in the negative effect of methanol on growth result from the fact that cells accumulate methanol to widely different concentrations depending on their physiological state. In their effort to detoxify from the high intracellular methanol and formaldehyde concentrations, cells oxidize considerably more methanol than they can incorporate into biomass. This leads to a useless ATP surplus, which the cells must hydrolyze without doing any useful biosynthetic work, and this results in lower bioma

ISSN:0006-3592    

DOI:10.1002/bit.260290110

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

年代:1987

数据来源: WILEY

摘要:

AbstractInvertase from baker's yeast (Saccharomyces cerevisiae) was covalently bound via benzoquinone and glutaraldehyde to a macroporous polystyrene anion exchanger. The behavior of the invertase–polystyrene complexes in batch and packed‐bed reactors was characterized kinetically. In addition to kinetic studies on sucrose hydrolysis at low initial substrate concentrations, the dependence of conversion degree on flow rate at high, industrially used substrate concentrations was determined. The described invertase–polystyrene complexes are suitable for technical application in the production of glucose–fructose mixtures because of their high specific and relative activities, as well as the good hydrodynamical and mechanical properties of the polystyrene

ISSN:0006-3592    

DOI:10.1002/bit.260290111

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

年代:1987

数据来源: WILEY