Rhodospirillum rubrum

utilization of condensed corn solubles for poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) production

Smith, R. L.
West, T. P.
Gibbons, W. R.

Department of Biology and Microbiology, South Dakota State University, Brookings, SD, USA

Correspondence Rebecca Smith, Department of Biology and Microbiology, South Dakota, State University, Brookings, SD 57007, USA. E-mail: [email protected]

2007/1314: received 16 August 2007, revised 4 October 2007 and accepted 22 October 2007

Journal of Applied Microbiology 104(5):p 1488-1494, May 2008.

Aims

This study sought to develop a less expensive medium for growth of the polyhydroxyalkanoate-producing bacterium Rhodospirillum rubrum from the ethanol production coproduct, condensed corn solubles (CCS).

Methods and Results

Small-scale trials using R. rubrum were performed in aerated or anaerobic stoppered serum bottles filled with media. The CCS (240 g l⁻¹) achieved a maximum cell density and growth rate comparable with the defined supplemented malate-ammonium medium (mSMN) or tryptic soy broth. Microaerophilic solubles medium cultures exhibited significantly higher maximum cell densities and growth rates than did strictly anaerobic cultures; while illumination, nickel or biotin addition had no effect. Growth of R. rubrum in a pH controlled bioreactor was significantly better in CCS (240 g l⁻¹) than in mSMN medium and supported production of 0·36% (cell dry weight) poly-(3-hydroxybutyrate-Co-3-hydroxyvalerate) after 24 h.

Conclusions

A CCS medium was devised that supported R. rubrum growth for biopolymer production as effective as the defined medium.

Significance and Impact of the Study

This study demonstrates that a more economical medium can be developed for biopolymer production using a low value coproduct from ethanol production. The impact is that this inexpensive solubles medium may make it more economical to produce the biopolymer on a commercial scale.