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 g L −1 medium-chain-length polyhydroxyalkanoate (PHA MCL ) and 0.57 g L −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°C and −41.21°C, respectively, by DSC. Its decomposition temperature was about 300°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 β- d -mannuronic acid and/or α- l -guluronic acid, and the β- d -mannuronic acid and/or α- l -guluronic acid residues were partially acetylated at position C2 or C3.