Relationship between culture redox potential and culture fluorescence inCorynebacterium glutamicum

Winter, Ellan; Rao, Govind; Cadman, Theodore W.

doi:10.1007/bf01875534

Cited by 12 publications

(1 citation statement)

References 7 publications

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“…The BioGuide system was developed to measure the level of intracellular NAD(P)H [i.e., the reduced forms of coenzymes NAD(P), nicotinamide adenine dinucleotide (phosphate)], on the basis of the property that the reduced coenzymes fluoresce at 460 nm when irradiated with 340-nm light, while the oxidized forms, i.e., NAD(P)+, do not fluoresce (BioChem Technology Inc., 1983). As it is the only analyzer available that provides information on intracellular conditions without process interruption, the fluorometer has been applied to many microbial fermentations, animal cell cultures, and biological wastewater treatment processes to generate information on cellular metabolism and to provide better process control in large-scale industrial operations (Armiger et al, 1986;Armiger et al, 1990;BioChem Technology Inc., 1983;Siano and Mutharasan, 1991;Srinivas and Mutharasan, 1987;Winter et al, 1988). It has excellent stability for long-term operation, and yet ita response is rapid enough to follow metabolic transitions occurring on the order of seconds.…”

Section: Introductionmentioning

confidence: 99%

Study of Nitrate Metabolism of Escherichia coli Using Fluorescence

Trivedi

1994

Biotechnology Progress

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Public concern about environmental nitrate contamination has increased significantly. To investigate the nitrate metabolism of Escherichia coli, profiles of NAD(P)H fluorescence responding to nitrate/nitrite additions to anaerobic E. coli cultures at the resting or minimum‐growth state were monitored by an on‐line fluorometer. Two different types of fluorescence profiles were observed. Upon nitrate addition, the fluorescence signal dropped instantaneously, indicating the presence of NAD(P)H‐dependent nitrate/nitrite reductases, without previous nitrate/nitrite induction. The signal remained at that level until all of the nitrate was reduced. In some cases, the signal then directly rose back to the earlier anaerobic level. In others, it partially recovered to an intermediate level, remained at that level for a period much longer than the first stage, and then returned to the anaerobic level. The single‐stage response implied that the nitrite formed by nitrate reduction was totally converted to ammonium simultaneously. The two‐stage response, however, resulted from intermediate nitrite accumulation: the rise in fluorescence at the end of the first stage signified nitrate depletion, and the second stage corresponded to reduction of the nitrite accumulated in the first stage. This is supported by the specific rates of nitrate and nitrite reduction determined from the fluorescence profiles. While the former (0.0138 ± 0.0026 g of NO3−‐N/(g of cells)‐h) was about the same in all the runs conducted, the latter was found to be 1 order of magnitude lower than the former in cultures showing the two‐stage response. The presence of ammonium, at 0–50 ppm NH4+‐N, was found to have no appreciable effect on the nitrate reduction rate for the E. coli studied.

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Section: Introductionmentioning

confidence: 99%

Study of Nitrate Metabolism of Escherichia coli Using Fluorescence

Trivedi

1994

Biotechnology Progress

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Use of fluorometry for monitoring and control of a bioreactor

Humphrey

1991

Biotech & Bioengineering

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A new fluorescent bioreactor monitoring probe-multiple excitation fluorometric system (MEFS)-has been developed. This probe was compared to the commercially available BioChem Technology FluroMeasure system (NADH probe). In this task the fluorescence behavior of three model fermentation systems, ethanol fermentation by Candida utilis, phenol fermentation by Pseudomonas putida, and glucose fermentation by Saccharomyces cerevisiae, were examined. The results indicated that the fluorescence intensity and behavior of various cellular fluorophors vary significantly between the different fermentation systems. Monitoring a fermentation process using only NAD(P)H fluorescence provided limited information. The NAD(P)H fluorescence was found not to be the best fluorescence signal for monitoring cell concentrations. The best way of monitoring a bioreactor by fluorometry may be to monitor several fluorophors in the whole culture broth simultaneously and to relate these fluorescence signals to various biological parameters.

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Utility of culture redox potential for identifying metabolic state changes in Amino acid fermentation

Kwong

Rao

1991

Biotech & Bioengineering

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We investigated the relationship of dissolved oxygen and culture redox potential (CRP) on amino acid production. Corynebacterium glutamicum ATCC 14296 was used for all experiments. The fermentation can be divided into a growth phase and a production phase. Our results indicate that in order to get higher amino acid production, a lower oxygen supply during the exponential phase is favored. A higher oxygen supply rate appears to be necessary during the production phase. Culture redox potential (CRP) was used to monitor the fermentation. CRP readings were observed to drop to a characteristic minimum value as the metabolic state changed from a growth to production phase. This was evidenced by the commencement of amino acid production and a simultaneous uptake of lactate. Upon lactate exhaustion, the CRP increased abruptly. At the same time, maximal amino acid yields were observed. By the use of minimum CRP as an indication of metabolic phase changes, the agitation rate was changed to increase oxygen supply during the production phase. This significantly increased amino acid production. These results show that culture redox potential measurements can be used to monitor and optimize amino acid production by process manipulation.

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Relationship between culture redox potential and culture fluorescence inCorynebacterium glutamicum

Cited by 12 publications

References 7 publications

Study of Nitrate Metabolism of Escherichia coli Using Fluorescence

Study of Nitrate Metabolism of Escherichia coli Using Fluorescence

Use of fluorometry for monitoring and control of a bioreactor

Utility of culture redox potential for identifying metabolic state changes in Amino acid fermentation

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