Research On Purification And Decoloring Process Of Nisin Z

The Nisin Z fermentation supernatant with an antibiotic activity of about1000IU/mL removed by centrifugal sedimentation was treated as waste water after Nisin Z being adsorpted to the production strain cells in industrial production. A protocol to obtain high purity Nisin Z by a combination of macroporous adsorption resin chromatography, acetone-salt aqueous two-phase and medium pressure preparative liquid chromatography from fermentation supernatant was established. Hence, decreased Nisin Z production costs, reduced the resource waste and environmental pollution.HZM-3was selected for the first cleaning-up procedure of Nisin Z for its higher separation efficiency than other tested4resins. The Nisin Z fermentation supernatant at pH7was pumped onto the colume at a flow rate of20BV/h.70%ethanol with a pH3was used as eluant while the elution flow rate was2BV/h. At the breakthrough point of5%, dynamic adsorption capacity of HZM-3resin for Nisin Z and the supernatant fluid is30.75mg/g and350mL/g, respectively. The purity of Nisin Z increased about95fold from0.28%to26.65%after enriched by HZM-3resin. The thermodynamic parameters indicated that the adsorption was an endothermic process and could be well described by Langmuir equation. The adsorption rate of the initial stage and the later stage were controlled by liquid film diffusion and intraparticle diffusion, respectively.Desorption solution of Nisin Z from HZM-3resin was decolorized by acetone-salt aqueous two-phase system. The volume ratio between desorption solution and acetone was1:1. And the purity increased to55.43%after aqueous two-phase system decolorization.The decolorized Nisin Z was refined by preparative chromatography after dissolved again by water. The optimum conditions for preparative liquid chromatography were as follows:sample size, sample concentration, and flow rate were20mL,30mg/mL and5mL/min, respectively. After the preparative liquid chromatography separation, the purity of Nisin Z was94.12%. The overall recovery and decolorization ratio was71.39%and95.7%, respectively.The HPLC retention time of purified Nisin Z powder after vacuum drying at303K was in line with that of Nisin Z standard. The molecular weight of the final product was3330Da, which was in accordance with that of Nisin Z.