Romanian Biotechnological Letters Vol. 15, No. 4, 2010 Copyright © 2010 University of Bucharest Printed in Romania. All rights reserved ORIGINAL PAPER 5467 PHAs accumulation in Pseudomonas putida P5 (wild type and mutants) in lipid containing media Received for publication, March 12, 2009 Accepted, July 27, 2010 CATALINA VOAIDES 1,2 , DIANA GROPOSILA 1,2 , MATILDA CIUCA 3 , IRINA LUPESCU 2 , ANETA POP 4 , CALINA PETRUTA CORNEA 1,2 1 Faculty of Biotechnology, University of Agronomic Sciences and Veterinary Medicine Bucharest, Romania 2 Center of Applied Biochemistry and Biotechnology BIOTEHNOL - Bucharest 3 National Institute of Research-Development in Agriculture Fundulea, Romania 4 Faculty of Veterinary Medicine, University of Agronomic Sciences and Veterinary Medicine Bucharest, Romania Corresponding author: Catalina VOAIDES, e-mail: catalinavoaides@gmail.com, tel. +40213182567 Abstract Polyhydroxyalkanoates (PHAs) are polyesters of hydroxyalkanoates synthesized by various bacteria as intracellular carbon and energy storage compounds and accumulated as granules in the cytoplasm of cells. In this work, we describe the isolation and characterization of Pseudomans putida P5 strain, as well as of some of its derivatives (mutants and recombinants) regarding the accumulation of PHAs. All the strains were subjected to fermentation and showed PHA accumulation with glucose, gluconate or octanoate as carbon source. In order to obtain PHA produced by these strains, a special procedure was developed, which allowed 80% PHA recovered. Differences in msc-PHA accumulation were observed in chemically induced mutants. RAPD analysis of these mutants proved that some rearrangements are produced as result of mutagenesis. The best results concerning msc-PHA accumulation were obtained when 0.4% octanoate was used. Different other lipid substrates (vegetal oils) were tested in order to establish the best substrate that allowed the largest accumulation of PHA. The results showed that the selected strains of P.putida (wild type or mutant) could utilize oil waste in the medium as a carbon source better than that of glucose and thus could substantially lower the cost of production of PHA. Keywords: Polyhydroxyalkanoates, Pseudomans putida, carbon source, mutants, recombinant strains Introduction Plastic materials are taking an important place in our every day life. Their physical properties make them very convenient in utilization. But these non-degradable plastics are accumulating in the environment at the rate of 25 million tones per year [6]. That is why replacement solutions like the using of biopolymers (biodegradable polymers) have been envisaged. On that purpose different kinds of polyesters (polyhydroxyalkanoates (PHAs), polylactides, aliphatic polyesters and polysaccharides) have been studied during the last 80 years. PHAs have very interesting physical properties and biodegradable abilities [14, 15]. They could be as well used in packaging as in medical applications due to their biocompatibility and to their slow hydrolytic degradation [10]. Polyhydroxyalkanoates (PHAs) are biodegradable polyesters synthesized by various bacteria [4, 11]. They represent products with biotechnological importance due to their special properties [1]. They are accumulated intracellular as carbon and energy reserves under certain conditions and can be detected through various methods based on PHA granule specific staining. To date, approximately 120 different constituents of PHAs have been identified. Various detection methods such as Sudan black B, Nile red or Nile blue staining were described and widely used to isolate bacterial PHA producers.