Original Paper

Bioprocess and Biosystems Engineering

, Volume 31, Issue 2, pp 145-152

Software sensors for fermentation processes

  • Heléne SundströmAffiliated withSchool of Biotechnology, Royal Institute of Technology
  • , Sven-Olof EnforsAffiliated withSchool of Biotechnology, Royal Institute of Technology Email author 

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Four software sensors based on standard on-line data from fermentation processes and simple mathematical models were used to monitor a number of state variables in Escherichia coli fed-batch processes: the biomass concentration, the specific growth rate, the oxygen transfer capacity of the bioreactor, and the new R O/S sensor which is the ratio between oxygen and energy substrate consumption. The R O/S variable grows continuously in a fed-batch culture with constant glucose feed, which reflects the increasing maintenance demand at declining specific growth rate. The R O/S sensor also responded to rapid pH shift-downs reflecting the increasing demand for maintenance energy. It is suggested that this sensor may be used to monitor the extent of physiological stress that demands energy for survival.


Software sensor Oxygen transfer Biomass Growth rate Stress Process analytical technology (PAT)