Aconitic acid (propene-1,2,3-tricarboxylic acid) is the most prevalent 6-carbon organic acid that accumulates in sugarcane and sweet sorghum. As a top value-added chemical, aconitic acid may function as a chemical precursor or intermediate for high-value downstream industrial and biological applications. These downstream applications include use as a bio-based plasticizer, cross-linker, and the formation of valuable and multi-functional polyesters that have also been used in tissue engineering. Aconitic acid also plays various biological roles within cells as an intermediate in the tricarboxylic acid cycle and in conferring unique survival advantages to some plants as an antifeedant, antifungal, and means of storing fixed pools of carbon. Aconitic acid has also been reported as a fermentation inhibitor, anti-inflammatory, and a potential nematicide. Since aconitic acid can be sustainably sourced from renewable, inexpensive sources such as sugarcane, molasses, and sweet sorghum syrup, there is enormous potential to provide multiple streams of additional income to the sugar industry through downstream industrial and biological applications that we discuss in this review.

During raw sugarcane processing, a significant portion of lost sucrose is attributable to microbial degradation. Sucrose consumption by many bacteria is also linked to the production of exopolysaccharides (EPS) such as dextrans and fructans. These resulting EPS cause operational challenges during raw sugar manufacturing. Here, we report the characterization of EPS from a fructan-forming Gluconobacter japonicus bacterium that we previously isolated from a Louisiana sugarcane factory. The genome sequencing revealed the presence of two encoded levansucrase genes, lsrA and lsrB. One levansucrase, LsrB, was detected in the secreted protein fraction of G. japonicus LASM12 by QTOF LC-MS. The spotting assays indicated that G. japonicus produces EPS using sucrose and raffinose as substrates. The G. japonicus EPS correlated with levan fructan commercial standards by ¹H-NMR, and with the characteristic carbohydrate fingerprint region for FTIR spectra, confirming that the G. japonicus EPS is levan fructan. The glycosyl composition and glycosyl linkage analysis revealed a linear β-2,6-fructofuranosyl polysaccharide with occasional (5.7%) β-2,1-fructofuranosyl branches. The gel permeation chromatography of the levan fructan EPS showed two main peaks at 4.5 kDa and 8 kDa and a very minor peak at 500 kDa. G. japonicus was identified as a producer of levan fructan. These findings will be useful for future studies aimed at evaluating the impact of levan fructans on sugar crop processing, which have been historically underestimated in industry.

Amplicon-based sequencing was utilized to address long-ignored gaps in microbiological knowledge about the diversity of microbes present in processing streams at Louisiana sugarcane raw sugar factories. These results support an emerging model where diverse organisms contribute to sugarcane juice degradation, help to contextualize microbial contamination problems faced by raw sugar factories, and will guide future studies on biocontrol measures to mitigate sucrose losses and operational challenges due to exopolysaccharide production.

The development and commercialization of sustainable chemicals from agricultural products and by-products is necessary for a circular economy built on renewable natural resources. Among the largest contributors to the final cost of a biomass conversion product is the cost of the initial biomass feedstock, representing a significant challenge in effective biomass utilization. Another major challenge is in identifying the correct products for development, which must be able to satisfy the need for both low-cost, drop-in fossil fuel replacements and novel, high-value fine chemicals (and/or commodity chemicals). Both challenges can be met by utilizing wastes or by-products from biomass processing, which have very limited starting cost, to yield platform chemicals. Specifically, sugar crop processing (e.g., sugarcane, sugar beet) is a mature industry that produces high volumes of by-products with significant potential for valorization. This review focuses specifically on the production of acetoin (3-hydroxybutanone), 2,3-butanediol, and C4 dicarboxylic (succinic, malic, and fumaric) acids with emphasis on biochemical conversion and targeted upgrading of sugar crop products/by-products. These C4 compounds are easily derived from fermentations and can be converted into many different final products, including food, fragrance, and cosmetic additives, as well as sustainable biofuels and other chemicals. State-of-the-art literature pertaining to optimization strategies for microbial conversion of sugar crop byproducts to C4 chemicals (e.g., bagasse, molasses) is reviewed, along with potential routes for upgrading and valorization. Directions and opportunities for future research and industrial biotechnology development are discussed.

Sugar beet is a major source of consumable sugar in domestic and industrial applications in the United States. Sugar beet roots are stored for up to 280 days under cold ambient temperature conditions in the Red River Valley (RRV) of Minnesota and North Dakota. During this period, storage rots often develop that can reduce the sucrose content and processing quality of the roots. Knowledge of the pathogens responsible for this sucrose loss is limited but crucial for devising management strategies. This study was conducted to re-examine and identify storage pathogens infecting sugar beet roots in outdoor nonventilated piles in the RRV of Minnesota and North Dakota and characterize their prevalence and geographic distribution. In the first year of the study, more than 50 roots exhibiting storage rot were collected from an outdoor nonventilated pile (ONVP) in Minnesota. In successive years, 150 storage rot and damaged symptomatic roots were collected from five geographically distinct ONVPs with three located in Minnesota and two located in North Dakota. Penicillium spp., Geotrichum candidum, and Mucor spp. were common filamentous fungal species identified, whereas Pichia membranifaciens was the dominant yeast identified in both years of the study. Leuconostoc mesenteroides and Gluconobacter cerinus were common bacterial isolates in both years of the study. Most of the bacterial isolates obtained from ONVP-4 (North Dakota) (63%) and ONVP-5 (North Dakota) (99%) during the second year of the study were identified as L. mesenteroides. This study identified fungal and bacterial species associated with storage diseases of sugar beet roots in the RRV of Minnesota and North Dakota, which is pivotal for implementing management strategies to minimize postharvest sucrose losses during sugar beet storage.

Leuconostoc bacteria are common colonizers of sugar crop processing environments, resulting in sucrose losses and the formation of exopolysaccharides (EPS) and biofilms that can lead to reduced product quality and higher operational costs. Although Leuconostoc species are present in abundance, strain-specific differences in biofilm formation, EPS production, and matrix structure are not well understood. In this study, nine sugar beet factory-derived Leuconostoc isolates were grown and evaluated using a combination of batch adherence and continuous flow biofilm bioreactor assays, cryo scanning electron microscopy (SEM), EPS quantification, viscosity testing, and growth rate analysis to determine which phenotypes correlate with biofilm formation. The results from the adherence batch-phase biofilms indicated significant phenotypic variation among isolates, with the highest bacterial proliferation by L. suionicum BSDF25-7 and BSDF48-3, exceeding 5 × 10 ⁸ colony-forming units/cm ² on stainless steel coupons. In contrast, the highest biofilm biomass accumulated was BSDF2-3 and BSDF25-7, indicating differences in cell proliferation and biofilm matrix structure. CryoSEM imaging revealed diverse biofilm structures, such as silo-like aggregates and patchy surface colonization, indicating strain-specific extracellular matrix assembly strategies. Flow-through biofilm bioreactor assays further identified BSDF2-3 and BSDF5-1 as predominant biofilm formers with the highest CFU/cm ² present at 4 × 10 ⁸ and 1 × 10 ⁹ , respectively, while BSDF2-3 accumulated twice the biofilm biomass as BSDF5-1. Leuconostoc strains BSDF25-7 and BSDF48-3 produced high levels of dextran and EPS, while BSDF2-3 consistently formed dense, shear-resistant biofilms despite slow growth and low EPS levels, suggesting the possibility of alternative matrix composition or structural adaptations. Individual Leuconostoc strains adapt uniquely, adding to the functional diversity of biofilms that impact formation, matrix complexity, and resistance to environmental stressors. This study furthers our understanding of EPS and growth phenotypes involved in biofilm formation while providing a working model, enabling the development of future antimicrobial mitigation strategies.