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Journal of Chemistry
Volume 2019, Article ID 8369179, 8 pages
https://doi.org/10.1155/2019/8369179
Research Article

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Production by Rhodospirillum rubrum Using a Two-Step Culture Strategy

1Beijing Key Laboratory of Biomass Waste Resource Utilization, Biochemical Engineering College, Beijing Union University, Beijing 100023, China
2Center for Biorefining, and Department of Bioproducts and Biosystems Engineering, University of Minnesota, Saint Paul, MN 55108, USA

Correspondence should be addressed to Yanling Cheng; ude.nmu@211gnehc

Received 15 April 2019; Accepted 13 June 2019; Published 4 August 2019

Academic Editor: Nenad Ignjatović

Copyright © 2019 Jie Liu 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

Polyhydroxyalkanoates (PHAs) are microbially synthesized biopolyesters which have attracted great attentions as a new biological material, potential alternative to traditional fossil fuel-based plastic due to their biodegradability and biocompatibility. Poly-3-hydroxybutyrate (PHB) and poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) are the most common members of PHAs. In this study, the nonsulfur and facultatively phototrophic bacterium Rhodospirillum rubrum was cultivated to accumulate PHA by a two-step culture strategy. Gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), and nuclear magnetic resonance spectroscopy (NMR) analyses showed that PHAs synthesized from fructose was PHBV, in which the 3HV content was 46.5 mol%, which means the better mechanical property. The molecular weight, distribution, and thermal features were characterized by gel permeation chromatography (GPC), differential scanning calorimeter (DSC), and thermo gravimetric analysis (TGA), respectively. The low PDI of 1.08 revealed the narrow and evenly molar mass distribution which shows the stable features. The high melting temperature and their other physical properties implied their potential applications. The traditional process of producing PHBV involves related carbon sources such as valeric acid. However, our study clearly described a new medium formula with fructose and a complete fermentation method to produce PHBV with a high 3HV faction and low molecular distribution.