Environment and Ecology Research Vol. 4(4), pp. 231 - 236
DOI: 10.13189/eer.2016.040407
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Autotrophic Growth of Paracoccus denitrificans in Aerobic Condition and the Accumulation of Biodegradable Plastics from CO₂

Kenji Tanaka ^1,*, Shunya Mori ¹, Mai Hirata ¹, Hiromi Matsusaki ^2
1 Department of Biological and Environmental Chemistry, Faculty of Humanity-Oriented Science and Engineering, Kindai University, Japan
² Department of Food and Health Sciences, Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Japan

ABSTRACT

The cell growth on H₂ and O₂ as the energy source and CO₂ as the sole carbon source in the autotrophic culture condition was tested for the gram-negative bacteria Paracoccus spp. The aerobic growth in the autotrophic condition was only observed in Paracoccus denitrificans NBRC13301 and P.pantotrophus NBRC102493. Both strains were sensitive to O₂ in particular the growth of P.pantotrophus was completely inhibited at the concentrations above 2% O₂. P.denitrificans grew until 15% O₂ however the optimum O₂ concentration was 5%. The growth characteristic of P.denitrificans was investigated by pH-controlled batch culture with supplying the gas mixture of H₂, O₂ and CO₂. The specific growth rate was 0.12 h^-1 at 5% O₂, 30℃ and pH7.0. The growth was much slower than other hydrogen-oxidizing bacteria however P.denitrificans accumulated biodegradable plastic, polyhydroxybutyrate, PHB with the content of 57.3% w/w in the cell under nitrogen limitation. Under DO limitation, the cell concentration increased to 25 g/L without accumulating PHB if NH₃ solution as the nitrogen source was fed sufficiently.

KEYWORDS
Polyhydroxyalkanoates, Paracoccus, Hydrogen-oxidizing Bacterium

Cite This Paper in IEEE or APA Citation Styles
(a). IEEE Format:
[1] Kenji Tanaka , Shunya Mori , Mai Hirata , Hiromi Matsusaki , "Autotrophic Growth of Paracoccus denitrificans in Aerobic Condition and the Accumulation of Biodegradable Plastics from CO₂," Environment and Ecology Research, Vol. 4, No. 4, pp. 231 - 236, 2016. DOI: 10.13189/eer.2016.040407.

(b). APA Format:
Kenji Tanaka , Shunya Mori , Mai Hirata , Hiromi Matsusaki (2016). Autotrophic Growth of Paracoccus denitrificans in Aerobic Condition and the Accumulation of Biodegradable Plastics from CO₂. Environment and Ecology Research, 4(4), 231 - 236. DOI: 10.13189/eer.2016.040407.