Abstract

Due to the effects of molecular weight (Mw) of a polymer on its properties, influencing factors on the Mw of poly-3-hydroxybutyrate (PHB) synthesized by methanotrophs were studied. Of the four kinds of methanotrophs, Methylosinus trichosporium IMV 3011 (IMV 3011) was found to be able to produce the PHB with the highest Mw value (1.2 M) under normal condition and then used for the other research on Mw of PHB. With methanol total concentration of 0.30 % (v/v), the Mw of PHB synthesized by the IMV 3011 can reach higher Mw (1.4 M) under the optimized cultivated condition. And with some essential substrates added, the Mw of PHB accumulated intracellular also changed. Moreover, through the study on the key enzymes activities in PHB metabolism under different cultivated condition, it was suggested that the Mw of PHB be controlled by the activity of key enzymes and the kind of microorganisms. This conclusion may also contribute to the synthesis of PHB with different Mw in an appropriate microorganism.

Key words: Molecular weight (Mw), poly-3-hydroxybutyrate, methanotrophs, methane, poly-3-hydroxybutyrate (PHB) synthetase.