Classifying dextrans and levans from sugar crop processing microbial isolates with FTIR spectroscopy, machine...

The presence of sucrose-consuming microorganisms and their associated exopolysaccharides (EPS) causes operational challenges for sugar crop (e.g. sugarcane, sugar beet) processing facilities during raw sugar manufacturing. To better prevent factory losses from issues related to microbially-derived EPS, it is necessary to develop easy-to-implement characterization methods for EPS. The two primary types of EPS associated with sugar crop processing are dextrans and levan fructans, which occur to varying degrees during raw sugar production. Chemometric techniques applied to characterization of these EPS can efficiently distinguish between dextran and levan based on their structural differences.

In this study, EPS was produced from several bacterial strains isolated from sugarcane and sugar beet factories. These EPS, along with dextran and levan 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 using machine learning techniques (linear discriminant analysis, support vector machine and k-nearest neighbors). These results are also consistent with dextran- and levan-producing genes identified through whole genome sequencing for the bacterial isolates.

The analyses presented in this study demonstrate a low cost, relatively non-labor-intensive analytical classification method for possible identification/characterization of EPS in raw sugar production. Implementation of this type of analytical approach at sugar crop processing facilities and/or laboratories has potential to improve engineering practices for EPS management. Future work applied to mixed samples, polycultures, or sugar crop juices could be explored to further develop chemometric applications. Published 2025. This article is a U.S. Government work and is in the public domain in the USA.