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As. Pac. J. Mol. Biol. & Biotech., June 2006 Vol. 14, 1-10

Ammonium Uptake and Growth Kinetics of Pseudomonas putida PGA1.

Annuar, M.S.M1*, Tan, I.K.P2, Ibrahim, S3 and Ramachandran, K.B.4

1,2Institute of Biological Sciences, Faculty of Science, 3Department of Civil Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia
4Department of Biotechnology, Indian Institute of Technology (IIT) Madras, Chennai-600036, India

*Author for Correspondence.
Institute of Biological Sciences,
Faculty of Science,
University of Malaya,
Kuala Lumpur 50603, MALAYSIA.
Tel: 6-03- 7967-6740
Fax:6-03-7967-4178
E-mail:suffian_annuar@um.edu.my

Abstract.
Ammonium uptake kinetics of low specific growth rate cultures of Pseudomonas putida PGA1, a gram negative fluorescent pseudomonad, which is an important producer of poly(3-hydroxyalkanoates) (PHA) molecules, were studied. The ammonium uptake follows a first-order kinetics model, indicating that the micro-organismís specific uptake rate of ammonium and its growth would increase as the ammonium ion concentrations become higher. Optimal ammonium uptake and growth rates were observed at 0.1 gL-1 ammonium ion in aqueous medium. It also indicated that the ammonium transport mechanism is probably inducible by ammonium concentration. The limit of ammonium ion level increase before cells stop growing completely is given by the substrate inhibition constant, Ki which equals to 1.2 gL-1 ammonium ion concentration.

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