• KSBB Journal
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• v.25 no.6
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• pp.559-564
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• 2010

A new hydrogen-oxidizing bacterium, Aeromonas sp. strain JS-1, that can fix $CO_2$ via the reductive pentose phosphate cycle (Calvin-Benson cycle) under chemoautotrophic conditions but not photoautotrophic conditions was isolated from fresh water. Strain JS-1 showed considerable $CO_2$ fixation ability during continuous cultivation even at high $CO_2$ concentration. Strain JS-1 used $H_2$ and $CO_2$ fixation as energy and carbon sources, respectively. Carbon dioxide fixation is carried out through the Calvin-Benson cycle, in which ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) is the key enzyme. Hydrogen-oxidizing chemoautotrophic Aeromonas sp. strain JS-1 exhibited remarkedly strong RubisCO [EC 4.1.1.39] activity. RubisCO was purified as an $L_8S_8$-type hexadecamer with molecular mass of 560 kDa by gel filtration. The enzyme consisted of two different subunits eight large (56 kDa) and eight small (15 kDa), as demonstrated by SDS-PAGE. The specific activity of the purified enzyme was about 3.31 unit/mg and stable up to $45^{\circ}C$. The $K_m$ values for RuBP, $CO_2$, and $Mg^{2+}$ were estimated to be 0.25 mM, 5.2 mM and 0.91 mM, respectively.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.461-464
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• 2002

A Chemoautotroph identified as an Aeromonas sp. strain JS-1 was isolated from fresh water. Aeromonas sp. strain JS-1 used the $H_2$ and $CO_2$ as energy and carbon sources, respectively. Growth characteristics for improving the $CO_2$ fixation rate were examined in batch cultivation. Its results shown that the optimal growth appeared at culture conditions of $35^{\circ}C$, pH 7 and NaCl 0.1%(w/v). Some hydrogen-oxidizing bacteria were reported that the enzyme activity of ribulose 1,5-bisphosphate carboxylase- oxygenase (RubisCO-EC 4.1.1.39), in the key enzyme of the Calvin-Benson cycle. A RubisCO was purified from a chemoautotrophic bacterium, Aeromonas sp. strain JS-1. the enzyme was purified by ammonium sulfate precipitation, DEAE-sepharose CL-6B and gel filtration chromatography. The RubisCO showed that molecular mass was about 560KDa from gel filtration chromatography and nondenaturing PAGE, and the RubisCO was confirmed to consist of $L_8S_8$ enzyme structure by sodium dodecyl sulfate polyacrylamide gel electrophoresis. A large subunit was about 56KDa and small one was about 15kDa. The Km values of the enzyme for ribulose 1,5-bisphosphate(RUBP), $NaH^{14}CO_3$, and $Mg^{++}$ were estimated to be 0.25mM, 5.2mM, and 0.91mM, respectively. The optimum temperature for RubisCO enzymatic activity were $50^{\circ}C$, and the enzymatic activity was stable up to $45^{\circ}C$.