Research On Curdlan Fermentation Conditions

Curdlan is a water insoluble exopolysaceharide produced by bacteria undernitrogen—limiting conditions. The unique physical and chemical properties make it’srange of applications very wide. But curdlan’s core production technology was fullymastered by foreign companies. The purpose of this paper is to achieve in thedomestic industrial production of Curdlan, and enhance the market competitiveness ofdomestic products.This article includes the following contents:1. Established the basic components of Curdlan fermentation medium, throughthe single factor experiment.I.e. sucrose, MgSO4,cornsyrup,(NH4)2HPO4,KH2PO4,CaCO3. First，Plackett-Burman design was adopted to screen out the important factors affecting theoutput of Curdlan：sucrose，(NH4)2HPO4， MgSO4and corn syrup．Then the pathof the steepest ascent was utilized to approach the optimal region．At last，theoptimized medium was obtained by Box-Behnken design and response surfacemethodology．Under the condition(sucrose61g/L、MgSO41g/L、corn syrup2.5g/L、(NH4)2HPO42.4g/L、KH2PO41.4g/L、CaCO31.4g/L)，the result of fermentation（47.73g/L） was increased by about35.6％compared with the previous condition（35.2g/L）．And then used the single factor experiment to optimize the cultureconditions. The optimized culture conditions: temperature was30℃, rotation speedwas200r/min,5%of the inoculum size, Medium volume was80ml/500ml, initial pHwas7.0, fermentation time was5d.2. Controlled the pH of the fermentation process by feeding of NaOH, whichreplaced CaCO3. Biomass of the fermentation broth was2.1g/L, the yield of Curdlanreached48g/L, the gel strength of the fermentation broth reached2700g/cm2, the gelstrength of the final product reached875g/cm2. Improves the competitiveness ofenterprises by improving the yield and quality of products and reducing productioncosts.3. The fermentation conditions were getting better, From5L automatic fermentertank to1m3fermenter tank. On this basis, using10m3fermenter tank to productCurdlan, the final yield of the fermentation broth reached52g/L, the fermentationtime was reduced to66hr. Fully explained that the large-scale industrial production ofCurdlan was entirely feasible.