Comparative Analysis of Different Properties of Polyhydroxyalkanoates Isolated from Two Different Bacterial Strains: Alkaliphilus oremlandii OhILAs and Recombinant Escherichia coli XL1B Nilkamal Pramanik, Khushi Mukherjee, Arpita Nandy, Shritama Mukherjee, Patit Paban Kundu Advanced Polymer Laboratory, Department of Polymer Science and Technology, University of Calcutta, Calcutta 700009, India The authors have no conflicts of interest to declare. Correspondence to: P. P. Kundu (E - mail: ppk923@yahoo.com) ABSTRACT: We synthesized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3-HB-co-3-HV)] copolymer having different contents of 3- hydroxyvalerate (3-HV) units (16.04, 16.3, 24.95, 25.62, and 16.52 mol % 3-HV) with different yields of polyhydroxyalkanoates (PHAs) by feeding with different cooking oils and with Alkaliphilus oremlandii OhILAs strain. The PHA production efficiency of the Alkaiphilus strain was compared with that of the control strain, Bacillus cereus. The synthesis of each PHA biopolymer was performed with different toxic spent oils as the sole carbon source in an oil-in-water-based microemulsion medium. We observed that the productivity of the poly(3- hydroxybutyrate) [P(3-HB)] copolymer from the Alkaliphilus strain was higher than those of the PHAs isolated from B. cereus and the Escherichia coli XL1B strain. The synthesized PHA copolymers were characterized by 1 H-NMR and Fourier transform infrared (FTIR) spec- troscopy. In the 1 H-NMR spectra, a doublet resonance peak at 1.253 ppm of the/ methyl protons of the 3-hydroxybutyrate (3-HB) side group and one at 0.894 ppm due to the methyl protons of the 3-HV side group indicated the presence of 3-HB and 3-HV units in the copolymer. The chemical shift values at 1.25 and 2.2 ppm, due to the resonance absorption peaks of the methyl protons and methylene protons, confirmed the synthesis of the P(3-HB) homopolymer. From the FTIR spectra, a strong C@O stretching frequency in the range of 1745–1727 cm 21 , together with strong CAO stretching bands near 1200 cm 21 and a strong band near 3400 cm 21 , confirmed the synthesis of P(3-HB-co-3-HV) and P(3-HB). Thus, waste cooking oil as a substrate provided an alternate route for the formation of P(3-HB-co-3- HV) and P(3-HB) by Alkaliphilus and E. coli strains, respectively. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41080. KEYWORDS: biocompatibility; biodegradable; biosynthesis of polymers Received 8 February 2014; accepted 30 May 2014 DOI: 10.1002/app.41080 INTRODUCTION Poly(3-hydroxybutyrate) [P(3-HB)] {with its poly(3-hydroxybuty- rate-co-3-hydroxyvalerate) [P(3-HB-co-3-HV)] copolymer} is a com- mon and versatile polymer of polyhydroxyalkanoate (PHA); it was first described by Lemoigne, 1 a French scientist, in the year 1925. Because various bacterial strains among Gram-positive and Gram- negative bacteria have been identified to accumulate PHAs with dif- ferent chain lengths both in aerobic and anaerobic conditions and in the presence of excess carbon and limited nutritional factors, such as nitrogen, phosphorus, and potassium, in the presence of excess car- bon. 2 P(3-HB) can readily be produced from renewable resources, such as sugars, fatty acids, and plant oil, as intracellular storage com- pounds; this provides a reserve of carbon and energy for microorgan- isms. Studies have also shown that some bacteria can accumulate high levels of PHA per cellular dry mass for the intracellular storage of carbon and as an energy source for their survival. 3,4 Researchers are more prone to improving the yield of biobased plastics by DNA modification 5 technology to reduce production costs and carbon dioxide emissions. Li et al. 6 and Theodorou et al. 7 have described a method for the augmentation of the yield of a polymer by the introduction of direct genetic changes by recombi- nant DNA technology in host microbial cells. The active intermedi- ates of PHA synthase of the recombinant strain are also a major factor in the synthesis of practical bioplastics. 4 In addition to the low-cost and high-productivity production of P(3-HB) from recombinant bacterial strains, researchers have also been able to store biocopolymers in the cytoplasm of genetically modified bacte- rial strains by the addition of sufficient precursors. 8,9 P(3-HB-co-3- HV) is a copolymer formed by the monomers 3-hydroxyl butanoic acid and 3-hydroxyl pentanoic acid or valeric acid. The formation of the P(3-HB-co-3-HV) copolymer with the addition of these pre- cursors (valeric acid, propionic acid, etc.) has been analyzed by many researchers. 10 Numerous bacteria synthesize and accumulate P(3-HB) as a carbon and energy-storage material, but the direct synthesis of the P(3-HB-co-3-HV) copolymer from the carbon source without any precursors has been found to be limited. 10 V C 2014 Wiley Periodicals, Inc. WWW.MATERIALSVIEWS.COM J. APPL. POLYM. SCI. 2014, DOI: 10.1002/APP.41080 41080 (1 of 12)