Optimizing antimicrobial dosing of bacterial isolates from sugar beet factories to reduce sucrose losses

Authors: Bruni, Gillian; Terrell, Evan; Zimmerman, Tia; YASSIN, ZIANAB - Beet Sugar Development Foundation; JOSHI, SANJAY - Oak Ridge National Laboratory

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2026
Publication Date: 3/10/2026
Citation: Bruni, G.O., Terrell, E.C., Zimmerman, T.E., Yassin, Z., Joshi, S. 2026. Optimizing antimicrobial dosing of bacterial isolates from sugar beet factories to reduce sucrose losses. Applied and Environmental Microbiology. Article e01646-25. https://doi.org/10.1128/aem.01646-25.
DOI: https://doi.org/10.1128/aem.01646-25

Interpretive Summary: Bacterial growth in sugar beet factories results in sucrose losses and operational challenges during raw sugar extraction resulting in lost revenue. Optimal concentrations for controlling bacterial growth were determined from sensitivity experiments with 58 bacterial isolates and several industrial biocides to find the lowest concentration (minimum inhibitory concentration (MIC)) needed to stop bacterial growth. Biocides tested in the study include sodium hypochlorite (bleach), Hydritreat 2216 (peracetic acid), Hops BetaStabXL (hops acid), Avancid GL50 (glutaraldehyde), thyme oil, and ammonium bisulfite. Growth curve experiments using the MIC level of certain biocides such as sodium hypochlorite, peracetic acid, and hops acid indicates that growth is inhibited at early time points relevant to retention times in sugar beet factories. Elevated temperature was also examined for antimicrobial control relative to 28'. Incubation at 50' was found to dramatically stop growth of several bacteria, except for Bacillus. Economic analysis was also conducted to estimate revenue neutral, break-even prices for antimicrobial agent application at factory scale. This allows for comparison among different antimicrobials based on the extent to which sugar (and therefore, revenue) is saved by the inhibition of direct sucrose losses caused by bacterial growth.

Technical Abstract: Bacterial growth in sugar beet factories results in sucrose losses and operational challenges during raw sugar extraction resulting in lost revenue. Minimum inhibitory concentration (MIC) values of antimicrobial agents were measured by microdilution assay for optimized dosing to control 58 selected bacterial isolates previously obtained from sugar beet factory juices and biofilms. Hops BetaStab XL was effective against most Gram-positive bacteria at 16 ppm with the exception of a few resistant Leuconostoc and Weissella outliers where MIC values were measured as >1000ppm. Sodium hypochlorite showed broad spectrum activity against most Gram-positive bacteria with MICs typically at 250 ppm with the exception of three Leuconostoc sp. outliers exhibiting MIC values >1000. Gram-negative isolates had MIC values ranging from 250-500 ppm. Hydritreat 2216 (peracetic acid) also exhibited broad-spectrum activity against each group, respectively, with MIC values typically lower between 31-250 ppm. Similarly, thyme oil and ammonium bisulfite showed similar ranges of MIC values against all isolates ranging from 125 to >1000 and 63 to >1000, respectively. Elevated temperature was also examined for antimicrobial control relative to 28'. Incubation at 50' was found to dramatically attenuate growth of most genera tested except for Bacillus sp. and some Acinetobacter sp. Growth curve experiments with selected bacterial isolates treated with Hops BetaStab XL, sodium hypochlorite, or Hydritreat 2216 near the MIC value immediately inhibits growth at the earliest timepoints relevant for sugar beet processing in factories. Technoeconomic analysis was also conducted to estimate revenue neutral, break-even prices for antimicrobial agent application at factory scale. This allows for comparison among different antimicrobials based on the extent to which sugar (and therefore, revenue) is saved by the inhibition of direct sucrose consumption through microbial activity.