Purification of ε-poly-L-lysine from microbial fermentation broth using ion-exchange chromatography in a liquid-circulating fluidized bed

Abstract

ε-Poly-L-lysine (ε-PL) is a high-value biopolymer with broad applications in food, pharmaceuticals, and biomaterials. However, the current downstream process remains a major barrier to sustainable large-scale ε-PL biomanufacturing. In this study, a liquid-circulating fluidized bed (LCFB) ion-exchange chromatography using a cationic resin has been developed for the purification of ε-PL for the first time. The adsorption behavior of ε-PL on the resin was well described by the Langmuir isotherm and pseudo-second-order kinetic models. The constructed LCFB process achieved 95.53% recovery and 46.12% purity under the optimized conditions: adsorption at pH 7.0 and desorption with 1.0 mol/L NaOH at 1.5 bed volume per hour. Compared with the fixed-bed mode, the LCFB process demonstrated superior performance, including a 37.94% increase in resin utilization, a 29.28% reduction in alkali consumption and a 27.44% reduction in wastewater generation. The process was successfully scaled-up 30-fold while maintaining operational stability. After integrating LCFB process into our previously developed ε-PL purification scheme, the final ε-PL hydrochloride product exhibited (97.56 ± 0.90)% purity with (81.14 ± 1.18)% recovery. This study highlights the efficiency, scalability, and environmental friendliness of the LCFB process as a promising method for the industrial purification of ε-PL, it also providing a valuable low-emission framework that can be extended to the purification of other bio-based products.

Keywords

ε-poly-L-lysine / Liquid-circulating fluidized bed / Ion-exchange chromatography / Biomanufacturing

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Funding

Agricultural Science and Technology Independent Innovation Funding Program of Jiangsu Province(CX(24)3086)

Shandong Provincial Technology Innovation Guidance Program(YDZX2025104)

Jiangsu Basic Research Center for Synthetic Biology(BK20233003)

RIGHTS & PERMISSIONS

Jiangnan University