Fermenters are used to accelerate the metabolic reactions within heterogeneous systems and promote population growth of desirable fungi and bacterial cells. This is typically conducted by introducing enzymes or other microorganisms to organic substrates in a hermetically sealed container. The medium is continuously mixed and either aerated (aerobic fermentation) or starved of oxygen (anaerobic fermentation). Numerous additional parameters must be controlled during process monitoring, including the gaseous composition of the headspace; net temperature within the bioreactor; pH level of the system; pressure levels; and more.
Off-gas and dissolved gas analysis are key stages in fermentation process monitoring to maintain optimal bioreactivity conditions. This blog post will explore the performance of fermentation off-gas and dissolved gas analysis in more detail.
Fermentation Off-Gas Analysis
Hiden Analytical’s QIC BioStream is a multi-stream exit gas composition monitoring system that can be configured for fermenter process monitoring applications. It utilizes a sensitive sampling inlet and a proprietary selector valve that can rapidly detect and measure off-gas species above a concentration of 5 parts per billion (ppb).
The inlet samples gas flows from the headspace, which typically comprise up to 25% of the total fermentor volume and contain undissolved respiratory gases from the aeration feed alongside produced gases from reacting substrates. Off-gas sampling is one of the primary methods of quantitatively assessing the state of fermentation non-invasively. It can provide a wealth of information regarding the respiratory quotient (RQ) which can subsequently inform observations into growth kinetics and substrate consumption. This is an essential form of process monitoring for industrial fermentation applications.
Fermentation Dissolved Gas Analysis
The HPR-40 DSA Membrane Inlet Mass Spectrometer (MIMS) offers in situ monitoring of bioreactions in fermenters with real-time process monitoring of dissolved gas species. As a standalone unit, it provides outstanding precision with a selectively diffusive membrane that partitions dissolved gases from the liquid phase. This is ideal for process monitoring of alcohol fermentation and expanding ethanol production yields, as well as the conversion of sugars into lactic acids.
Dissolved gas analysis utilizes a submerged probe that acquires a liquid feed from the bulk fermentation fluid. This is then analysed to identify and measure the concentration of dissolved gas species. Chemical evolutions can be monitored as a function of time to determine the rates of various mechanisms such as oxygen uptake, which is a critical process in fermentation and can affect various end-product qualities.
Fermentation Process Monitoring with Hiden Analytical
Hiden Analytical is the UK’s leading supplier of quadrupole mass spectrometers for process monitoring of fermenters and bioreactors. Our QIC BioStream gas analyser was engineered for exit gas analysis of various bioprocesses and has demonstrated a powerful efficiency for real-time off-gas analysis in fermenter units. It can monitor multiple gas species in situ across a broad flow range from 4 ml/minute up to a possible 10l/minute. The HPR-40 DSA MIMS meanwhile offers sub-parts per billion (ppb) detection levels and analysis of dissolved species up to a 300 amu mass range.