Fermentation Optimization Of Calditerricola Satsumensis FAFU012 And Preparation Of Its Production Agents

Calditerricola satsumensis(C.satsumensis)FAFU012 is a hyperthermophilic bacterium that can participate in the high temperature reaction with the advantages of quick response rate and effective killing of pathogenic microorganisms in the biological treatment of organic pollution.Developing a cost-effective fermentation method and fermenting agent are beneficial for the extended application of C.satsumensis in the industrialization.In this study,C.satsumensis was isolated from the sludge composting,and its suitable fermentation culture medium and the preparation of fermenting agent were investigated.The results of the single factorial experiments demonstrated that soluble starch,sucrose and glucose were the most suitable carbon sources;yeast extract,hydrolyzed casein and trypsin were the best nitrogen sources;NaCl and MgCl2·6H20 were the most important inorganic salt.Moreover,the Plackett-Burman design method revealed that yeast extract,soluble starch and hydrolyzed casein were the key factors for the growth of strain FAFU012 in the culture mediun.Furthermore,steepest ascent experiments and response surface methodology(RSM)experiments confirmed that the most suitable culture medium for strain FAFU012 included 2.68 g/L of soluble starch,3.57 g/L of hydrolyzed casein and 5.15 g/L of yeast extract with sludge extract as the substrate.Then with the temperature of 75°C,initial pH of 7.5,inoculation volume of 2%,and shaking speed of 180 rpm,the optical density(OD600)of cells was up to 1.12 after fermentation,indicating the counting of 2.4×109 cfu/mL.On the basis of fermentation optimization,this study also developed a simple hyperthermophilic fermentation device to achieve the production of 20-L bentch-scale fermentation.Biochar,kaolin and wheat bran were used as carriers to prepare fermentation agent.The results showed that the highest viable count of fermented bacteria reached 2.8 billion/g for the preparation of strain FAFU012 with the carrier of wheat bran.This research provides a simple,economical and efficient method for the preparation of fermented microorganisms and the preparation of fermenting bacteria,which lays the foundation for the large-scale popularization and application of strain FAFU012.