The Influence of Dissolved Oxygen on Pseudomonas AM1 Grown on Methanol in Continuous Culture

S U M M A R YAs the interval between methanol additions to methanol-limited cultures of Pseudomonas methylotropha was increased beyond 20 s the yield of bacterial dry wt/g of methanol fell significantly. Discontinuous methanol additions also caused cycling in the values of a number of parameters, including pH, dissolved oxygen tension, CO, production and amino acid pool concentration. It is suggested that after each addition of methanol a burst of growth occurred, followed by a period of starvation. These observations are discussed in the light of continuous culture practice and theory.

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“…The carbon (methanol)-limited continuous culture media were described by MacLennan, Ousby, Vasey & Cotton (1971).…”

Section: Methodsmentioning

confidence: 99%

The Effect of Discontinuous Methanol Addition on the Growth of a Carbon-limited Culture of Pseudomonas

Brooks

Meers

1973

Journal of General Microbiology

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“…The effect of oxygen tension on methylotrophic bacteria was examined by Dalton's g r o~p~' , '~ and Maclennan et a1. 20. In M. capsulatus (Bath), Dalton et al noted that a high oxygen tension above a pOz of 0.1 atm inhibited nitrogen assimilation and reduced the growth rate under nitrate-or ammonium-limiting conditions.…”

Section: Introductionmentioning

confidence: 99%

Batch cultivation of Methylosinus trichosporium OB3b. I: Production of soluble methane monooxygenase

Park

Hanna

Taylor

et al. 1991

Biotech & Bioengineering

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Methanotrophs have promising applications in bioremediation and in the production of fuel-related chemicals due to their nonspecific enzyme, methane monooxygenase (MMO). The optimal conditions for cell growth and production of the soluble from of MMO (sMMO) were determined from batch cultivations of an obligatory methanotrophs, Methylosinus trichosporium OB3b, in shake flasks and a 5-L bioreactor. It was confirmed that a copper deficiency is essential for the formation of the cytoplasmic sMNO. Optimum cell growth without added copper was observed at pH 6.0-7.0, temperature of 30-34 degrees C, and phosphate concentration of 10-40 mM. In the bioreactor experiments, external CO(2) addition eliminated the long lag period observed in the absence of added CuSO(4), i.e., prior to the exponential cell growth phase. When methane was continuously supplied, the profile of the cell growth showed two different phases depending on the availability of nitrate, an initial fast exponential growth phase (specific growth rate, micro = 0.08 h(-1)) and a later slow growth phase (micro = 0.008 h(-1)). The cell density at the transition from a fast to a slow growth rate was proportional to the initial medium nitrate concentration in the range 5-20 mM and cell yield was estimated to be 7.14 g dry cell wt/g N. Whole-cell sMNO activity remained essentially constant regardless of the growth rate unit cell growth stopped. With an initial medium iron concentration below 40 mM, an abrupt decrease in sMNO activity was observed. The lower sMNO activity could be restored by supplying additional iron to the bioreactor culture. Cell yield on iron was estimated to be 1.3 x 10(3) g dry cell wt/g Fe.

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“…M extorquens AM1 and M organophilum DSM 760 were grown on the minimal medium (medium A) of MacLennan et al (31) or the minimal medium described previously (12), containing 0.5% (vol/vol) methanol, 0.2% (wt/vol) methylamine hydrochloride, or 0.2% (wt/vol) succinate. When required, filter-sterilized PQQ (Methoxatin; Fluka) was added to 1 ,uM.…”

mentioning

confidence: 99%

Isolation, phenotypic characterization, and complementation analysis of mutants of Methylobacterium extorquens AM1 unable to synthesize pyrroloquinoline quinone and sequences of pqqD, pqqG, and pqqC

et al. 1994

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Aerobic gram-negative methylotrophs oxidize methanol to formaldehyde by using a methanol dehydrogenase that has pyrroloquinoline quinone (PQQ) as a prosthetic group. Seventy-two mutants which are unable to grow on methanol unless the growth medium is supplemented with PQQ have been isolated in the facultative methanol utilizer Methylobacterium extorquens AM1. In addition, 12 previously isolated methanol oxidation mutants of M. extorquens AM1 were shown to be able to grow on methanol in the presence of PQQ. These putative PQQ biosynthesis mutants have been complemented by using previously isolated clones containing M. extorquens AM1 DNA, which were known to contain genes necessary for oxidation of methanol to formaldehyde (mox genes (27). MDH is a tetrameric enzyme located in the periplasm that contains pyrroloquinoline quinone (PQQ) as the prosthetic group and also contains Ca2+ (37,40). PQQ was first identified as the prosthetic group of MDH and is now also known to be the prosthetic group of a few other bacterial dehydrogenases that oxidize alcohols or sugars (9). The biosynthetic pathway of PQQ has not yet been determined, but the biosynthetic precursors are known to be tyrosine and glutamate (19).

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The Influence of Dissolved Oxygen on Pseudomonas AM1 Grown on Methanol in Continuous Culture

Cited by 67 publications

References 5 publications

The Effect of Discontinuous Methanol Addition on the Growth of a Carbon-limited Culture of Pseudomonas

The Effect of Discontinuous Methanol Addition on the Growth of a Carbon-limited Culture of Pseudomonas

Batch cultivation of Methylosinus trichosporium OB3b. I: Production of soluble methane monooxygenase

Isolation, phenotypic characterization, and complementation analysis of mutants of Methylobacterium extorquens AM1 unable to synthesize pyrroloquinoline quinone and sequences of pqqD, pqqG, and pqqC

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