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 (PHAMCL) and 0.57 g L−1 alginate oligosaccharides (AO) were obtained at the end of the process. GC/MS was used to characterize the PHAMCL, which was found to be a polymer mainly consisting of 3HO (3-hydroxyoctanoate) and 3HD (3-hydroxydecanoate). Tm and Tg values for the PHAMCL 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.