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BioMed Research International
Volume 2013 (2013), Article ID 237806, 7 pages
http://dx.doi.org/10.1155/2013/237806
Research Article

Improved Properties of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Produced by Comamonas sp. EB172 Utilizing Volatile Fatty Acids by Regulating the Nitrogen Source

1Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
2Department of Process and Food Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
3Department of Biological Functions and Engineering, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino,Wakamatsu-ku, Kitakyushu, Fukuoka 808-0196, Japan

Received 9 April 2013; Revised 3 August 2013; Accepted 8 August 2013

Academic Editor: José Luis Campos

Copyright © 2013 Mohd Rafein Zakaria et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This study presents the effect of carbon to nitrogen ratio (C/N) (mol/mol) on the cell growth and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) accumulation by Comamonas sp. EB172 in 2 L fermenters using volatile fatty acids (VFA) as the carbon source. This VFA was supplemented with ammonium sulphate and yeast extract in the feeding solution to achieve C/N (mol/mol) 5, 15, 25, and 34.4, respectively. By extrapolating the C/N and the source of nitrogen, the properties of the polymers can be regulated. The number average molecular weight ( ) of P(3HB-co-3HV) copolymer reached the highest at 838 × 103 Da with polydispersity index (PDI) value of 1.8, when the culture broth was supplemented with yeast extract (C/N 34.4). Tensile strength and Young’s modulus of the copolymer containing 6–8 mol% 3HV were in the ranges of 13–14.4 MPa and 0.26–0.34 GPa, respectively, comparable to those of polyethylene (PE). Thus, Comamonas sp. EB172 has shown promising bacterial isolates producing polyhydroxyalkanoates from renewable carbon materials.