Performance of Short Chain Length Polyhydroxyalkanoate Production by Comamonas sp EB172 in Large Scale Bioreactors Based on Constant Impeller Tip Speed
Tabassum Mumtaz *
Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia and Microbiology and Industrial Irradiation Division, Institute of Food and Radiation Biology, Bangladesh Atomic Energy Commission, Dhaka 1000, Bangladesh
Mitra Mohammadi
Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia and Department of Environmental Science, Kheradgerayan Motahar Institute of Higher Education, Iran
Lian- Ngit Yee
Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
Suraini Abd-Aziz
Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
Phang Lai Yee
Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
Hidayah Ariffin
Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
Yoshihito Shirai
Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu 808-0196, Japan
Mohd Ali Hassan
Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
*Author to whom correspondence should be addressed.
Abstract
Aims: In this study, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) or PHBV, a short chain length polyhydroxyalkanoates (PHAs) production by a local isolate Comamonas sp. EB172 using 500 g/L mixed organic acids were investigated in 10 L and 150 L stirred tank bioreactors based on constant impeller tip speed (minimum 0.56 m/s and maximum 2.22 m/s).
Results: The ratio of the three acids i.e., acetic, butyric, and propionic, were 2:1:1, mimicking clarified mixed acids obtained from anaerobically treated palm oil mill effluent. In pH controlled fed-batch cultivation, in 10 L bioreactor, the strain could accumulate 84% PHBV with biomass concentration of about 4.08 g/L under dual nutrient limitation strategy i.e., dissolved oxygen and nitrogen limited conditions. By maintaining similar tip speed in 150 L bioreactor, a final biomass concentration of 5.35 g/L with a PHBV content of 72% and volumetric productivity of 0.083 g/L/h were obtained. The calculated yield was 0.259 g PHBV/g mixed acids.
Conclusion: Both the yield and PHA content in 150 L bioreactor were comparable to that obtained in 10 L scale where PHBV content ranged from 70- 90% (w/w) of the cell with yield of 0.27- 0.4 g PHBV/g mixed acid, respectively. This is the first report of utilizing mixed organic acids for PHBV biosynthesis in large scale.
Keywords: Comamonas sp. EB172, mixed organic acids, PHBV, impeller tip speed