Analytical Sciences

Rapid and Direct Compositional Analysis of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in Whole Bacterial Cells by Thermally Assisted Hydrolysis and Methylation–Gas Chromatography

Siti BAIDURAH,* Yasuko KUBO,* Mitsuhiro KUNO,* Kazuho KODERA,* Yasuyuki ISHIDA,* Tsuneo YAMANE,** and Hajime OHTANI***

*Department of Biological Chemistry, College of Bioscience and Biotechnology, Chubu University, 1200 Matsumoto-cho, Kasugai 487-8501, Japan
**Department of Environmental Biology, College of Bioscience and Biotechnology, Chubu University, 1200 Matsumoto-cho, Kasugai 487-8501, Japan
***Department of Materials Sciences and Engineering, Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan

Thermally assisted hydrolysis and methylation–gas chromatography (THM-GC) in the presence of an organic alkali was applied to the direct analysis of copolymer composition for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] accumulated in whole bacterial cells. Cupriavidus necator was grown on a liquid medium with different molar ratios of valeric acid (V) to glucose (G) in order to control the compositions of P(3HB-co-3HV) produced in the cells. Trace amounts (0.03 mg) of dried Cupriavidus necator cells were directly subjected to THM-GC in the presence of tetramethylammonium hydroxide (TMAH) at 400°C. The obtained chromatograms clearly showed nine characteristic peaks, attributed to the THM products from 3HB and 3HV units in the polymer chains, without any appreciable interference by the bacterial matrix components. Based on these peak intensities, the copolymer compositions were determined rapidly without using any cumbersome sample pretreatment. Moreover, the compositions thus obtained were in good agreement with those obtained by the conventional technique.

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