Production of Polyhydroxybutyrate by halotolerant Halomonas cerina YK44 using sugarcane molasses and soybean flour in tap water.

As environmental pollution intensifies, the interest in bioplastics is growing. The bioplastic polyhydroxyalkanoates (PHAs), which are produced and degraded by microorganisms, have received considerable attention. However, the production cost of PHA is still high, and several ways to increase economy of PHA production have been studied. Therefore, as one way of solution, Halomonas species were screened and evaluated with cheap substrates such as molasses and soybean flour. Among tested strains, Halomonas cerina YK44 was selected and used for polyhydroxybutyrate (PHB) production with molasses and soybean flour together, whose combination was not evaluated well before, in tap water. The medium composition optimization showed maximum PHB production at 4 % sugarcane molasses, 2 % NaCl, 0.05 % soybean flour, and pH 8 in tap water (9.2 g/L DCW, 7.3 g/L PHB, and 79.7 % PHB contents). However, cell growth of halotolerant H. cerina YK44 was disturbed by 0.2 % furfural, which existed in biomass based sugars as inhibitors. Physical and thermal analyses revealed that PHB film started from sugarcane molasses and soybean flour was no different from that initiated from simple sugars (Tm was 175.8 °C and 176.2 °C, PDI was 1.29, and 1.31, respectively).