Quantitative Mass Analysis of Polyhydroxybutyrate　(PHB)　Production from Single Recombinant Escherichia coli Bacterial Cells using Laser Induced RF Plasma Charge Detection quadrupole Ion Trap Mass Spectrometer

Shao-Yu Liang^1,2*, Yu-Tze Horng², Po-Chi Soo², Wen-Ping Peng¹

¹Physics, National Dong Hwa University, Hualien, Taiwan
²Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien, Taiwan

* Presenter:Shao-Yu Liang, email:810814202@gms.ndhu.edu.tw

Polyhydroxyalkanoates (PHAs) is a group of the bio-synthesis polymers extracted from various bacteria. The properties of PHAs are similar to biodegradable polypropylene (PP) and polyethylene (PE) polymers. Because of their nontoxic and biodegradable characteristics, PHA polymers is thus treated as ideal bioplastic materials which might be potentially used to replace petroleum-based plastics in many fields such as food packaging or medical materials. However, the PHAs have to be extracted and purified in proper conditions that makes a higher cost of production and time consuming in extraction and purification.
We present for the first time that quantitative mass analysis of one kind of PHA copolymers, polyhydroxybutyrate (PHB), produced from single Escherichia coli SY-4 cells. The mass analysis can be accomplished by using a laser induced RF plasma charge detection quadrupole ion trap mass spectrometer (LIRFP CD QIT-MS). The LIRFP CD QIT-MS can analyze each sample within 20 minutes and the PHB mass production can be validated by gas chromatography (GC) analysis which takes few days to analyze the amount of PHB production. The GC could determine the methyl esters of the PHB generated from the digestion of the bacterial pellets with acidic methanolysis. But it shows no information of the PHB produced from each single cells.
The rate of PHB production from E. coli SY-4 was determined by LIRFP CD QIT-MS and the PHB mass could be obtained by comparing the mass difference between E. coli SY-4 (genetic modified E. coli cells for PHB production) and E. coli XL1-Blue (wild type, no PHB production). The PHB production is about 8%, 29%, 48%, 55%, and 54% of each single E. coli SY-4 cell for 6 hours, 12 hours, 24 hours, 36 hours, and 48 hours, respectively. The PHB mass production rate of E. coli SY-4 cells using ion trap mass spectrometer is consistent with that measured by GC method. This indicates the ion trap method can potentially be used for real-time analysis of massive PHB production from batch or chemostat production.

Keywords: Charge Detection quadrupole Ion Trap Mass Spectrometer, Bio synthesis polymers, Laser Induced Plasma