Bioconversion of Crude Fish Oil Into Poly-3-hydroxybutyrate by Ralstonia sp. M91
Đoàn Văn Thược, V. T. M. Anh
Abstract
The biosynthesis of polyhydroxyalkanoates from crude fish oil by bacteria isolated from soil samples was investigated. More than 200 bacterial colonies were isolated, among them 15 isolates were selected and tested for their abilities to synthesize PHA from crude fish oil. Eight strains were found to produce the poly-3-hydroxybutyrate (PHB) from crude fish oil with PHB content ranging from 7.4 to 50.1 wt %. The highest PHB producing bacterium (strain M91) was chosen for further studies. Based on the 16S rRNA gene sequences, strain M91 was classified into genus Ralstonia. In flask experiment, high cell dry weight (CDW) of 3.93 g/L and PHB concentration of 2.43 g/L were obtained by strain M91 when cultured in the medium containing 15 g/L crude fish oil. The CDW and PHB concentration were then increased to 5.32 and 2.73 g/L, respectively, when strain M91 was cultivated in 10-liter bioreactor. The production of PHB by Ralstonia M91 using crude fish oil as an inexpensive carbon source is expected to reduce the production cost and motivates further studies.