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Electronic Journal of Biotechnology
Universidad Católica de Valparaíso
ISSN: 0717-3458
Vol. 12, No. 2, 2009
Bioline Code: ej09011
Full paper language: English
Document type: Research Article
Document available free of charge

Electronic Journal of Biotechnology, Vol. 12, No. 2, 2009

 en Influence of metal ions and organic carbons on denitrification activity of the halotolerant bacterium, Paracoccus pantotrophus P16 a strain from shrimp pond
Pintathong, P.; Richardson, D.J.; Spiro, S. & Choorit, W.

Abstract

The effect of metal ions, ferric ion (Fe3+) and molybdenum ion (Mo6+) on the denitrification process of Paracoccus pantotrophus P16 grown under saline conditions was investigated. Results revealed that the dosages of added Fe3+ and Mo6+ significantly accelerated nitrate utilization and nitrite accumulation. Enzymatic studies revealed that the membrane-bound nitrate reductase and the periplasmic nitrite reductase had activities of 998 ± 28 and 373 ± 18 nmol (mg protein)-1 min-1, respectively after growing Paracoccus pantotrophus P16 in medium supplemented with 1.5 μM Fe3+. If provided with 1.5 μM Fe3+ and 2.4 μM Mo6+, the membrane-bound nitrate reductase activity increased to 6,223 ± 502 nmol (mg protein)-1 min-1 and the periplasmic nitrite reductase was 344 ± 20 nmol (mg protein)-1 min-1. The results indicated that an addition of Fe3+ and Mo6+ led to an overstimulation of nitrate reductase activity as compared with nitrite reductase activity. When glucose was supplied, the minimal ratio of carbon per nitrate (C/N) was 2.31 mg C/mg NO3 --N with denitrification yield of 0.45 g NO3 --N/g C. Addition of ethanol instead of glucose, the minimal ratio of C/N was 1.15 mg C/mg NO3 --N with denitrification yield of 1.08 g NO3 --N/g C.

Keywords
metal ions, nitrate reductase, nitrite accumulation, nitrite reductase, Paracoccus pantotrophus

 
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