Optimization And Scale-up Of Bioprocess For Echinocandin B Production

Echinocandin B(ECB),a novel polypeptide-antibiotic produced by Aspergillus nidulans,is a precursor for the synthesis of anti-fungal drug-anidulafungin.In this work,the Aspergillus nidulans ZJB09223 strain was selected for ECB production mutagenized by our lab.Fed-batch strategy was used to further improve ECB production based on medium optimization by our research group,parameters were optimized in 30 L fermentor,fermentation kinetics model was built and 2 t/a ECB production process design was designed,the major reserch results are as follows:The effect of precursors and mannitol fed-batch on ECB biosynthesis were studied.L-proline and L-ornithine was selected to study the effect on ECB biosynthesis by pulse feeding.Addition of L-proline in combination with L-ornithine at every 2 d with the final concentrations of 7.0 g/L respectively for three times significantly improved the production of ECB,a ECB titer of 1604.4 mg/L was achieved,which was 70.2% higher than that of without precursors added.Upon this results,fed-batch fermentation was carried out at an initial mannitol level of 49.0 g/L,then,16.0 g/L of mannitol was added every 3 d for three times.By way of this novel feeding strategy,a maximal ECB titer and yield coefficient of up to 1915.4 mg/L and 83.26 mg/g dry cell weight respectively was achieved,which was 103.2% and 32.6% respectively higher than the control(942.5 mg/L and 62.81 mg/g DCW).The effct of process conditions on ECB production were studied in 30 L fementor based on early study by our research group.The optimized parameters were as follows: seed age 48.0 h,inoculum size 10%,culture temperature 24.0 °C,ventilation 1.5 vvm,fermentor pressure 0.03-0.04 MPa,pH 6.0-7.5,initial agitation 150 rpm,then feedback controlled by DO.Under the above conditions,the maximum ECB production reached to 885.8 mg/L,148.5% higher than that of the initial conditions(356.5 mg/L).The ECB fermentation kinetics model was built and curve fitting got close to the true value.An annual output of 2 t ECB production process design was carried out in this work.The design main contents included technological process design of fermentation and separation,material calculation,energy calculation,“three wastes” treatment and cost accounting.