Simultaneous production and characterization of medium-chain-length polyhydroxyalkanoates and alginate oligosaccharides by Pseudomonas mendocina NK-01

When Pseudomonas mendocina NK-01 was cultivated in a 200-L fermentor using glucose as carbon source, 0.316 gL(-1) medium-chain-length polyhydroxyalkanoate (PHA(MCL)) and 0.57 gL(-1) alginate oligosaccharides (AO) were obtained at the end of the process. GC/MS was used to characterize the PHA(MCL), which was found to be a polymer mainly consisting of 3HO (3-hydroxyoctanoate) and 3HD (3-hydroxydecanoate). T(m) and T(g) values for the PHA(MCL) were 51.03 degrees C and -41.21 degrees C, respectively, by DSC. Its decomposition temperature was about 300 degrees C. The elongation at break was 700% under 12 MPa stress. MS and GPC were also carried out to characterize the AO which had weight-average molecular weights of 1,546 and 1,029 Da, respectively, for the two main components at the end of the fermentation process. MS analysis revealed that the AO were consisted of beta-D-mannuronic acid and/or alpha-L-guluronic acid, and the beta-D-mannuronic acid and/or alpha-L-guluronic acid residues were partially acetylated at position C2 or C3.