Study On Fermentation Techniques Of The Gellan Gum

Gellan gum is the most developing microbial gum in recent years, It has advantages of low consumption, thermal stability, acid resistance and superior taste properties, flexibility and hardness adjustable, good compatibility, etc. Gellan gum is widely used as suspending agent, stabilizer, thickener, emulsifier, film former and the lubricants in cosmetics, food, chemical and other fields. At present, the industrial production yield of gellan gum is low, and it has a high energy consumption and high production costs. Using modern biotechnology methods to improve the yield of gellan gum and quality, will be the future of gellan gum production and research.Sphingomonaspaucimobilis ATCC 31416 is used as research material in this paper.With flask fermentation, we optimized its fermentation parameters to obtain high yield rate and low-cost fermentation technology. To reduce the effect of dissolved oxygen in gellan gum fermentation, additional carbon source and oxygen carrying agent was added during fermentation to reduce the inhibition of initial carbon sources on bacteria and the oxygen transfer rate in the yield of gellan gum, ultimately achieve the purpose of increasing production. The main contents are as follows:Viscosity of fermentation broth and crude rubber yield rate is settled as the parameters in this experiment, determinate the bacterial growth curve in seed flask and fermentation flask, Fermentation parameters such as seed age, initial pH, culture temperature, rotation speed, liquid volume, inoculation size were optimized through single factor optimization. By using orthogonal experimental design, we ultimately determined the optimum fermentation conditions as follow: seed age was 18 h; liquid volume was 10%; temperature is 28℃; initial pH 7.0 ; rotation speed of 220 rpm; inoculation size was 10%.We studiy three common oxygen-carrying agent (H2O2, dodecane, Triton X-100) during fermentation in this experiment, addition oxygen species, adding time and add content was optimized by using single factor optimization method. The best combination type was determined to be optimal oxygen-carrying agent and add conditions. Optimal oxygen-carrying agent is H2O2, the optimal time for adding is 40 ~ 44 h, the optimum addition level is 20μL/50 mL, compared with the control group increased by 103.37%. Optimal combination of adding type is dodecane and H2O2, the production rate compared with the control group increased by 124.54% Two-step adding method is determined to be the best combination of carbon sources: 2% of the initial carbon source, glucose; supplemented with 4% maltose carbon source, The best time for adding carbon is 18 h.In this study, with gellan gum yield and viscosity of fermentation broth as the index, with single factor optimization, the type and content of carbon and nitrogen source in the medium are as follows the amount of MgSO4, KH2PO4 and other factors, initially identified more appropriate kind and amount. And by response surface analysis to optimize, determine the optimum formula of the medium is: maltose 53.23 g / L, peptone, 3.536 g / L, MgSO4 3.191 g / L, KH2PO4 8.186 g / L, Na2HPO4 7.5 g / L, K2SO4 3 g / L; this condition, gellan gum production reached 3.8442%, the carbon conversion rate is 64.07%.