Determination of redox potential levels critical for cell respiration and suitable for <scp>L</scp>‐leucine production

Akashi, Kunihiko; Ikeda, Shigeho; Shibai, Hiroshiro; Kobayashi, Kaetsu; Hirose, Yoshio

doi:10.1002/bit.260200104

Cited by 33 publications

(6 citation statements)

References 13 publications

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“…However, CRP data can possibly reveal subtle differences in the oxygen uptake rate of different cells. According to the Nernst equation, CRP is linear with respect to logarithmic DO at constant temperature and pH under extremely low oxygen t e n s i o n~~~ (1) where a and b are constants dictated by medium composition and different species in the cells. Constants a and b were determined for each strain independently using CRP and DO signals from the redox and DO probes, respectively, between 1% to 2% air saturation.…”

Section: Culture Redox Potential and Effect Of Vhbmentioning

confidence: 99%

Improvement of Escherichia coli microaerobic oxygen metabolism by Vitreoscilla hemoglobin: New insights from NAD(P)H fluorescence and culture redox potential

Tsai

Rao

Bailey

1995

Biotech & Bioengineering

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On-line NAD(P)H fluorescence and culture redox potential (CRP) measurements were utilized to investigate the role of Vitreoscilla hemoglobin (VHb) in perturbing oxygen metabolism of microaerobic Escherichia coli Batch cultures of a VHb-synthesizing E. coli strain and the iso-genic control under fully aerated conditions were subject to several high/low oxygen transitions, and the NAD(P)H fluorescence and CRP were monitored during these passages. The presence of VHb decreased the rate of net NAD(P)H generation by 2.4-fold under diminishing oxygen tension. In the absence of aeration, the strain producing VHb maintained a steady NAD(P)H level 1.8-fold less than that of the control, indicating that the presence of VHb keeps E. coli in a more oxidized state under oxygen-limited conditions. Estimated from CRP, the oxygen uptake rates near anoxia were 25% higher for cells with VHb than those without. These results suggest that VHb-expressing cells have a higher microaerobic electron transport chain turnover rate. To examine how NAD(P)H utilization of VHb-expressing cells responds to rapidly changing oxygen tension, which is common in large-scale fermentations, we pulsed air intermittently into a cell suspension and recorded the fluorescence response to the imposed dissolved oxygen (DO) fluctuation. Relative to the control, cells containing VHb had a sluggish fluorescence response to sudden changes of oxygen tension, suggesting that VHb buffers intracellular redox perturbations caused by extracellular DO fluctuations.(c) John Wiley & Sons, Inc.

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Section: Culture Redox Potential and Effect Of Vhbmentioning

confidence: 99%

Improvement of Escherichia coli microaerobic oxygen metabolism by Vitreoscilla hemoglobin: New insights from NAD(P)H fluorescence and culture redox potential

Tsai

Rao

Bailey

1995

Biotech & Bioengineering

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“…Correspondingly, the measured CRP cannot be assigned to a particular intracellular or extracellular redox reaction (Srinivas et al, 1988). As a result, CRP has historically been utilized in microaerobic and anaerobic cultures where independent oxygen detection is difficult (Akashi et al, 1978;Srinivas et al, 1988). Recent studies, however, indicate CRP is useful for monitoring changes in the metabolic state of aerobic cultures (Kwong and Rao, 1991) and for optimizing yield of aerobic and anaerobic fermentation products (Kwong and Rao, 1992b).…”

Section: Introductionmentioning

confidence: 99%

Generating controlled reducing environments in aerobic recombinant Escherichia coli fermentations: Effects on cell growth, oxygen uptake, heat shock protein expression, and in vivo CAT activity

Gill

Joon

Jain

et al. 1998

Biotechnol. Bioeng.

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The independent control of culture redox potential (CRP) by the regulated addition of a reducing agent, dithiothreitol (DTT) was demonstrated in aerated recombinant Escherichia coli fermentations. Moderate levels of DTT addition resulted in minimal changes to specific oxygen uptake, growth rate, and dissolved oxygen. Excessive levels of DTT addition were toxic to the cells resulting in cessation of growth. Chloramphenicol acetyltransferase (CAT) activity (nmoles/microgram total protein min.) decreased in batch fermentation experiments with respect to increasing levels of DTT addition. To further investigate the mechanisms affecting CAT activity, experiments were performed to assay heat shock protein expression and specific CAT activity (nmoles/microgram CAT min.). Expression of such molecular chaperones as GroEL and DnaK were found to increase after addition of DTT. Additionally, sigma factor 32 (sigma32) and several proteases were seen to increase dramatically during addition of DTT. Specific CAT activity (nmoles/microgram CAT min. ) varied greatly as DTT was added, however, a minimum in activity was found at the highest level of DTT addition in E. coli strains RR1 [pBR329] and JM105 [pROEX-CAT]. In conjunction, cellular stress was found to reach a maximum at the same levels of DTT. Although DTT addition has the potential for directly affecting intracellular protein folding, the effects felt from the increased stress within the cell are likely the dominant effector. That the effects of DTT were measured within the cytoplasm of the cell suggests that the periplasmic redox potential was also altered. The changes in specific CAT activity, molecular chaperones, and other heat shock proteins, in the presence of minimal growth rate and oxygen uptake alterations, suggest that the ex vivo control of redox potential provides a new process for affecting the yield and conformation of heterologous proteins in aerated E. coli fermentations.

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“…Corynebacterium glutamicum is used industrially for large-scale production of amino acids (Akashi et al, 1978). While originally identified in a screen for organisms secreting L-glutamate, mutants of C. glutamicum have also been identified which produce various other amino acids.…”

Section: Introductionmentioning

confidence: 99%

A Review on Bio Prospective Potential of Corynebacterium glutamicum

Pattnaik¹

2019

Int.J.Curr.Res.Aca.Rev.

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Corynebacterium glutamicumis a nonpathogenic, aerobic, gram-positive soil bacterium used for the large-scale biotechnological production of several biomolecules. C. glutamicum is an industrial microbe traditionally used for the production of amino acids. It is a well known microbe as the workhorse in fermentation industry used since its first discovery in Japan in 1950s for production of monosodium glutamate (MSG)and L-lysine with a market size of 3.1 and 2.2 million. However, for the fermentative production of diverse products through genetic–metabolic engineering. Due to its industrial importance, several clones of C. glutamicum have been sequenced by both industry and academic groups. Furthermore it has also been exploited for the synthesis of a variety of other fuels and chemicals. Especially, the facultative anaerobic lifestyle of this Gram-positive bacterium formed the basis to engineer C. glutamicum for the production of reduced molecules such as organic acids (e.g., lactate, succinate) and alcohols (e.g., ethanol, isobutanol) under zero-growth anaerobic conditions. The present work is a review of various uses of C. glutamicum for which the researchers explored several resources including the PubMed database, Journals and online archives upto March 2019. The review in its analysis signifies the vital utility of C. glutamicum in various prospective. Most articles were on occurrence, metabolism, metabolic role, and industrial uses of bacterial polyhydroxyalkanoates. Through genetic alterations, this microbe showed its efficacy for the simultaneous utilization of hexose and pentose sugars of biomass hydrolysate for making value-added products, such as amino acids and polyamines, and thus making it a strain of choice to work in a bio-refinery concept. This soil microbe also showed its efficacy in bioremediation purposes, such as arsenic removal. Recently its extensive research has focused on engineering beyond the scope of amino acids for utilization of alternative carbon sources, (e.g. coming from wastes and unprocessed sources), and construction of C. glutamicum strains for production of new products such as diamines, organic acids and alcohols. Meanwhile, a variety of corynebacterial strains allows access to alternative carbon sources that allows production of a wide range of industrially relevant compounds. Some of these efforts set new standards in terms of titers and productivities achieved whereas others represent a proof-of-principle. These achievements manifest the position of C. glutamicum as an important industrial microorganism with capabilities far beyond the traditional amino acid production. According to the studies cited in different literatures C. glutamicum reported as the most effective and playing important roles as dominant bacteria in biotechnological applications as well as industrial processes and products. And, with recent advances in biotechnology, the economic contributions that these organisms can make in biotechnological applications and industrial processes can be exploited further for large scale benefit of mankind.

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Determination of redox potential levels critical for cell respiration and suitable for L‐leucine production

Cited by 33 publications

References 13 publications

Improvement of Escherichia coli microaerobic oxygen metabolism by Vitreoscilla hemoglobin: New insights from NAD(P)H fluorescence and culture redox potential

Improvement of Escherichia coli microaerobic oxygen metabolism by Vitreoscilla hemoglobin: New insights from NAD(P)H fluorescence and culture redox potential

Generating controlled reducing environments in aerobic recombinant Escherichia coli fermentations: Effects on cell growth, oxygen uptake, heat shock protein expression, and in vivo CAT activity

A Review on Bio Prospective Potential of Corynebacterium glutamicum

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