Takahira Ogawa

Assessment of Growth Yield of a Blue--green Alga, Spirulina platensis, in Axenic and Continuous Culture

Summary: An axenic and continuous culture of a blue—green alga, Spirulina platensis, was established in a Roux bottle. The opalescent plate method was used to measure the light energy absorbed by the cells and to assess the cell growth yield, Ynkcal i.e. the amount of dry algal cells harvested per kcal light energy absorbed. Values of Ynkcal calculated ranged from 0.01 to 0.02 g cell kcal−1.

The Role of NADH:Fe(III)EDTA Oxidoreductase in Ethylene Formation from 2-Keto-4-Methylthiobutyrate

Abstract A mechanism for the formation of ethylene from 2-keto-4-methylthiobutyric acid (KMBA), a deaminated derivative of l -methionine, was studied with NADH:Fe(III)EDTA oxidoreductase purified from Cryptococcus albidus IFO 0939. The characteristics of the reactions catalyzing the NADH:Fe(III)EDTA oxidoreduction and the formation of ethylene were compared and found to be almost identical. A chemical ethylene-forming system, composed of Fe(II)EDTA, KMBA and oxygen, was constructed and the characteristics of the formation of ethylene were compared with those of the enzymatic reaction. Both the enzymatic and the chemical ethylene-forming reactions were strongly inhibited by scavengers of free radicals, such as benzoic acid, hydroquinone and catalase, and both were activated by H2O2. From these results, we propose the following mechanism for the formation of ethylene from KMBA. The first step involves the NADH:Fe(III)EDTA oxidoreduction that is catalyzed by NADH:Fe(III)EDTA oxidoreductase, with Fe(II)EDTA always being supplied as the result. Oxidation of Fe(II)EDTA by molecular oxygen yields the superoxide radical anion (O2 . ) which can undergo the dismutation reaction to form hydrogen peroxide. Hydrogen peroxide in turn can react with Fe2+ via the Fenton reaction, generating the hydroxyl radical (OH•), which can serve as an oxidizing agent in the oxidation of KMBA to ethylene. The role of the activity of NADH:Fe(III)EDTA oxidoreductase in the formation of ethylene from KMBA in vivo is discussed.

Microbial production of C2-hydrocarbons, ethane, ethylene and acetylene

Article de synthese sur la production dans des conditions aerobies (champignons, levures, bacteries, actinomycetes)

Isobutene production by Rhodotorula minuta

SummaryIsobutene production by Rhodotorula minuta IFO 1102 was studied. It was confirmed that the gas species produced by this yeast was isobutene from the result of analysis with a gas chromatograph mass spectrometer. Oxygen supply was essential to the microbial production of isobutene. The optimum pH was found to be approximately pH 6.0 and optimum temperature 25°–27° C. Isobutene production rate was maximal when l-leucine and l-phenylalanine in the medium were being uptaken by the yeast.The results from an investigation of the role of l-leucine and l-phenylalanine suggested that l-leucine was the precursor of isobutene and l-phenylalanine the inducer for the enzyme concerned with isobutene production.

Ethylene production from L-methionine by Cryptococcus albidus

Abstract Cryptococcus albidus IFO 0939 was selected from microorganisms producing ethylene from l -methionine in a culture medium. When methionine was excluded from the culture medium of C. albidus , there was little production of ethylene. Ethylene production in a methionine-containing culture medium occurred for a brief period at the end of the growth phase. 2-oxo-4-methylthiobutyric acid (KMBA), a deaminated product of methionine, accumulated in the culture filtrate. An ethylene-forming enzyme was partially purified from C. albidus by means of DEAE-Sepharose CL-6B ion exchange chromatography, and a cell-free ethylene-forming system was constructed. Using this system, the precursor of ethylene was found to be KMBA and essential factors were NAD(P)H, Fe 3+ , EDTA and oxygen.

Effect of oxygen on the growth (yield) of Chlorella vulgaris

AbstractThe growth yield of Chlorella vulgaris, YkJ defined as g cells harvested per kJ of light energy absorbed by the cells, was assessed in a turbidostat culture by varying CO2 and O2 partial pressures (n

Reappraisal of the so-called light shielding of gas vacuoles in Microcystis aeruginosa

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The relationship between isobutene-forming activity and a cytochrome P-450 in Rhodotorula minuta

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