Real-time bioprocess monitoring using a mid-infrared fibre-optic sensor

This work proposes a simple, easy-to-fabricate and cost-efficient sensor based on mid-infrared (MIR) spectroscopy for in-situ real-time bioprocess monitoring. A process involving the production of sophorolipid biosurfactants by way of fermentation was studied with the aim of monitoring varying substrate and product concentrations over time and also distinguishing between the main two structurally different types of biosurfactant produced: lactonic and acidic sophorolipids. First, measurements were carried out using ATR-FTIR spectroscopy. This was followed by comparative measurements using a fabricated U-bent fibre-optic sensor designed for in-situ monitoring. It was demonstrated for the first time that varying concentrations of sophorolipids in a fermentation broth could successfully be monitored over time using an in-situ MIR fibre-optic sensor. Moreover, acidic and lactonic sophorolipids could simultaneously be identified at varying concentrations. The utilisation of such a sensor in bioprocesses can provide a wealth of real-time data, allowing for improved control of feeding rates and better process characterisation, providing significant opportunities for bioprocess control, resulting in increased production and decreased overall costs.