Rapid determination of 1,3-propanediol in fermentation process based on a novel surface-enhanced Raman scattering biosensor.

The production of 1,3-propanediol (1,3-PDO) is an important fermentation process. However, 1,3-PDO could not be distinguished separately and efficiently in fermentations previously because it has a highly similar molecular structure to the feedstock glycerol (GLY) and by-product lactic acid (Lac), which leads to the difficulty of quantification. In this paper, a low-cost and environmentally friendly biosensor based on surface-enhanced Raman scattering (SERS) technique was developed. Using it, the concentration of 1,3-PDO and Lac in a fermentation solution can be determined directly from their respective characteristic peaks in Raman spectroscopy. Moreover, by analyzing the respective contributions of 1,3-PDO, Lac, and GLY to the integrated intensities of the 2920 cm-1 Raman peak common to these three substances, the concentration of GLY could also be quantified. SERS study on various 1,3-PDO:GLY and Lac:GLY molar ratios were conducted to establish the proportional relationships of these compounds by analyzing the relationship between the concentration and the Raman peak intensities. The 1,3-PDO:Lac:GLY with serial concentration gradient was carried out to verify the relationship between the concentration and the Raman peak intensities by the high-performance liquid chromatography (HPLC) with relative deviations <25%. Concentrations of 1,3-PDO and Lac as low as 1 g/L and concentration of GLY as low as 4 g/L were analyzed to determine the limit of detection. Therefore, this new method allows the rapid quantification of 1,3-PDO, Lac and GLY concentrations on a SERS-based biosensor.