microPAT: A protocol for direct in vitro NMR observation of lactic acid bacteria fermentations

Author Summary: Lactic acid bacteria (LAB) are widely used in the food industry as starter cultures to manufacture fermented food, and more recently there has been an increasing interest in using LAB for biopreservation of food products. The study of the metabolism of these bacteria is therefore of great interest, and NMR is the only omics analytical technology that has the potential to measure their metabolome non-destructively. In vivo NMR can provide valuable information about the dynamic metabolism of microorganisms, for example for studying the adaptive responses of microorganism to different environmental and stress factors such as substrate, cohabitation, deleterious metabolites, as well as temperature and pH. This paper describes a protocol for in vitro NMR measurement of the fermentation of lactic acid bacteria. We call it microPAT (microbial process analytical technology) [1] as it monitors in real time the microbial processes of the fermentation. Some of the experimental issues that were encountered during the process of developing the protocol as well as the selected approach to overcome them are presented.