Hyper production of polyhydroxyalkanoates by a novel bacterium Salinivibrio sp. TGB11

Abstract

Strains of Salinivibrio genus are able to grow under wide range of NaCl concentration. Salinivibrio sp. TGB11, a novel bacterium screened from saltworks, was found capable of producing polyhydroxyalkanoates from sugars and volatile fatty acids. In shake flask cultures, the use of glucose, sucrose, acetate, and butyrate achieved poly(3-hydroxybutyrate) (PHB) titers of 5.00, 3.23, 0.77, and 0.88 g/L, respectively. The addition of 0.5 g/L propionate with glucose yielded 4.38 g/L poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), with a 3-hydroxyvalerate monomer content of 8.57 mol%, yet propionate concentration higher than 1.5 g/L severely inhibited cell growth. In fed-batch bioreactor studies, PHB titer of 100.22 g/L and PHBV titer of 59.30 g/L were achieved. The PHB production yield was 0.42 g/g, reaching 88% of the theoretical value. Salinivibrio sp. TGB11 showed the highest PHB titer and yield in Salinivibrio genus and could be a promising host for industrial purposes.