Original Paper

Journal of Industrial Microbiology & Biotechnology

, Volume 34, Issue 8, pp 561-566

On-line biomass measurements in bioreactor cultivations: comparison study of two on-line probes

  • K. KiviharjuAffiliated withLaboratory of Bioprocess Engineering, Helsinki University of Technology Email author 
  • , K. SalonenAffiliated withLaboratory of Bioprocess Engineering, Helsinki University of Technology
  • , U. MoilanenAffiliated withLaboratory of Bioprocess Engineering, Helsinki University of Technology
  • , E. MeskanenAffiliated withLaboratory of Bioprocess Engineering, Helsinki University of Technology
  • , M. LeisolaAffiliated withLaboratory of Bioprocess Engineering, Helsinki University of Technology
  • , T. EerikäinenAffiliated withLaboratory of Bioprocess Engineering, Helsinki University of Technology

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Abstract

Two on-line probes for biomass measurement in bioreactor cultivations were evaluated. One probe is based on near infrared (NIR) light absorption and the other on dielectric spectroscopy. The probes were used to monitor biomass production in cultivations of several different microorganisms. Differences in NIR probe response compared to off-line measurement methods revealed that the most significant factor affecting the response was cell shape. The NIR light absorption method is more developed and reliable for on-line in situ biomass estimation than dielectric spectroscopy. The NIR light absorption method is, however, of no significant use, when the cultivation medium is not clear, and especially in processes using adsorbents or solid matrix for the microorganism to grow on. The possibilities offered by dielectric spectroscopy are impressive, but the on-line probe technology needs to be improved.

Keywords

Biomass Cell density measurement Dielectric spectroscopy Near infrared light absorption On-line Viability