Applications of Raman spectroscopy in fermentation evaluation of resource microorganisms

Abstract:

Microbial fermentation is a process of substrate transformation by cell metabolism. In order to improve the yield of target products, we need to analyze the dynamic characteristics of microbial fermentation in a real-time manner so as to optimize the fermentation process. As a promising inline process analysis technology, Raman spectroscopy can achieve accurate monitoring under the in-situ conditions without causing microbial pollution and help optimize the microbial fermentation process. [Objective] To develop the prediction models with the inline Raman measurement technology and evaluate model performance so as to accurately monitor the concentration changes of glucose, xylose, ethanol, and lactic acid in the whole fermentation process of Zymomonas mobilis. [Methods] Raman spectra for multiple components in the fermentation process of Z. mobilis were collected in situ by the immersion probe, and then the partial least square method was adopted to conduct spectral processing and multivariate data analysis. The multivariate models were developed via the combination of Raman spectra with the HPLC data and then used to predict the concentrations of multiple components in the fermentation broth. [Results] The established models accurately measured the single products in the fermentation broth of Z. mobilis. Then, the prediction models for the concentrations of glucose, ethanol, and lactic acid were developed through multivariate analysis and validated, which can be used for real-time accurate determination of multiple components in the fermentation process. [Conclusion] We successfully established a Raman spectral analysis method for monitoring multiple chemicals in the fermentation broth. This is a promising technology for real-time monitoring of multiple substrates and products in industrial fermentation and can be used for strain development and process optimization of microorganisms.