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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Commodity Utilization Research » Research » Publications at this Location » Publication #397736
Research Project: Improved Conversion of Sugar Crops into Food, Biofuels, Biochemicals, and Bioproducts

Location: Commodity Utilization Research

Title: Classifying dextrans and levans from sugar crop processing microbial isolates with FTIR spectroscopy, machine learning and genomics

Author
item Terrell, Evan
item Bruni, Gillian
item Qi, Yunci

Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/2025
Publication Date: 8/15/2025
Citation: Terrell, E.C., Bruni, G.O., Qi, Y. 2025. Classifying dextrans and levans from sugar crop processing microbial isolates with FTIR spectroscopy, machine learning and genomics. Journal of the Science of Food and Agriculture. 105(15): pg8867-8877. https://doi.org/10.1002/jsfa.70125.
DOI: https://doi.org/10.1002/jsfa.70125

Interpretive Summary: During sugarcane processing, bacteria can consume sugar and produce polysaccharides as an unwanted byproduct. The two most important polysaccharides are known as dextran and levan, which are studied in this work. Dextran is usually considered to be the most important, but more recent literature suggests that impacts from levan on raw sugar production may be underestimated. First, polysaccharides were produced using bacteria that were previously collected from local sugar mills. Then, the combination of an easy-to-use analytical characterization method (FTIR spectroscopy) and some additional data analysis (principal component analysis) was used to determine if a given polysaccharide is a "dextran type" or a "levan type." Future work can explore extending this approach to potentially mixed dextran-levan samples, raw sugars/syrups firectly, and/or polysaccharides produced by more complicated bacterial cultures containing two or more strains. Ultimately, the goal of this kind of reasearch is: (a) to inform engineering and operations decisions in raw sugar production; (b) to produce higher quality sugar at lower cost with fewer contaminants.

Technical Abstract: The presence of sucrose-consuming microorganisms and their associated exopolysaccharides (EPS) causes operational challenges for raw sugar factories. To better prevent factory losses from issues related to microbially-derived EPS, it is necessary to develop easy-to-implement characterization methods for EPS. Two primary types of EPS are dextrans and levan fructans, which occur to varying degrees during raw sugar production. Chemometric techniques applied to the characterization of these EPS can efficiently distinguish between dextran and levan based on structural differences between the two types of EPS molecules/polymers. In this study, EPS was produced from three different isolated bacterial strains from factories in Louisiana. These EPS, along with relevant standards, were analyzed with Fourier transform infrared (FTIR) spectroscopy and subjected to principal component analysis (PCA). Results from PCA applied to FTIR allow for the ability to distinguish dextran from levan EPS. Analysis over second derivative spectra tended to give higher-quality results with less ambiguity. Future work applied to mixed samples or polycultures could be explored to further develop chemometric applications for identification and characterization of EPS in sugar factories.