Cell growth and P(3HB) accumulation from CO2 of a carbon monoxide-tolerant hydrogen-oxidizing bacterium, Ideonella sp. O-1

Cell growth and accumulation of polyhydroxybutyric acid, P(3HB), from CO 2 in autotrophic condition of a newly isolated hydrogen-oxidizing bacterium, the strain O-1, was investigated. The bacterium, which was deposited in the Japan Collection of Microorganisms as JCM17105, autotrophically grows by assimilating H 2 , O 2 , and CO 2 as substrate. 16S rRNA gene sequence of the bacterium was the closest to Ideonella dechloratans (99%). Specific growth rate of the strain O-1 was faster than a hydrogen-oxidizing bacterium, Ralstonia eutropha , which is well-known P(3HB)-producing microorganism. The strain O-1 is tolerant to high O 2 concentration and it can grow above 30% ( v / v ) O 2 , while the growth of R. eutropha and Alcaligenes latus was seriously inhibited. In culture medium containing 1 g/L (NH 4 ) 2 SO 4 , cell concentration of the strain O-1 and P(3HB) increased to 6.75 and 5.26 g/L, respectively. The content of P(3HB) in the cells was 77.9% ( w / w ). The strain O-1 was very tolerant to carbon monoxide (CO) and it grew even at 70% ( v / v ) CO, while the growth of R. eutropha and A. latus were seriously inhibited at 5% ( v / v ) CO. From these results, it is expected that the strain O-1 will be useful in the manufacture of P(3HB) because the industrial exhaust gas containing CO 2 , H 2 , and CO can be directly used as the substrate in the fermentation process.