Isothermal Calorimetry: A Novel Tool for Studying Biofilm Activity

Detecting and analysing the presence of micro-organisms is hugely important within biological applications. This is necessary to ensure the safety of public health; to track and develop antimicrobial resistance; and to act as a quality control within biotechnology and food production. Methods like ELISA assays are commonly used to fulfil these applications, but they can only detect the presence of pathogens rather than detailing their activity and how those change under certain conditions.  

Symcel is a company that has developed the first isothermal microcalorimeter for use in biological applications such as microbiology, probiotics & microbiome, and sterility testing. Their instrument the calScreener™ can accurately measure the heat produced from the metabolic processes of samples, which can then be directly translated to the total metabolic activity.

The calScreener

The calScreener™ essentially uses the 48-well calPlate containing medical-grade titanium cups, which are then sealed to make individual incubation systems. The calPlate is placed inside the calScreener’s thermostat chamber where the cups sit on a heat-flux sensor, allowing the heat flow of each sample to be measured and then viewed using the calView software.  

Symcel’s calScreener™ is a differential microcalorimeter, so the heat flow produced by the sample is measured against an inert reference (thermodynamic reference), which increases the sensitivity and quality of the signal as any disturbances can be cancelled out, increasing the signal-to-noise ratio. All of this allows cellular parameters to be studied in the correct way no matter the sample composition and morphology.

This is the calPlate. A 48-well plate with calVials.

Not only does Symcel produce this unique instrument, they also have optimised several parameters to create multiple advantages for the user, which include:


Biofilms are a community of micro-organisms that have aggregated together, typically on a surface. The organisms then produce an extracellular matrix, which supports the structure and creates a film like appearance. With current techniques we can obtain high-resolution images and real-time measurements, however understanding the metabolic activity deep within the biofilm continues to be a challenge – one that Symcel can solve!  

Monitoring the entire biofilm can be done using the high sensitivity of the calScreener™, which can detect very small amounts of heat from within the biofilm. The ability to monitor the metabolic activity of biofilms opens new research opportunities, such as real-time monitoring of biofilms under different conditions and optimising treatments against them. On top of this, the calScreener™ allows biofilms to be analysed without labels and in their natural conditions. One example of this can be seen in a recent application note from Prof. Tom Coenye at the university of Ghent, who is looking at compounds that boost biofilm metabolism.  

One method to reduce the resistance of biofilms to antimicrobials is to increase their metabolic rate. The calScreener™ can be used to analyse how different compounds influence the metabolism of a biofilms and help to find ideal compounds. In his application note, Prof. Tom Coenye looked at the effect of a G7 compound and the antibiotic ceftazidime (CAZ) on the P.aeruginosa biofilms. The calScreener™ was used to see how the metabolism of the biofilm changed when different concentrations of the compounds were used on their own and in combination, the results of which can be seen in figure 1. This gives researchers helpful insights into how biofilms can be treated and shows the importance of metabolic activity data in this application area.