Study On The Production Of Viable Cells Feed By Lactic Acid Bacteria With Fermentation Of Corn Starch Cake

The corn starch cake, the residual by-products from glucose manufacturing from corn, is rich in nutrients. However, they have not been utilized rationally and effectively. With the increasing negative effect of antibiotics, the microbial ecological agents have received considerable attention in recent years and it has been utilized as an antibacterial product after antibiotics. However, the high cost of lactic acid bacteria culture prevents its utilizing. Additionally, the small viable cells population in microbial ecological agents is also taken consideration. So the study was developed on viable cells feed additive production from corn starch cake to achieve its high value utilization.Lactobacillus Rhamnosus was used as a model strain for this study. The experiment was carried out on liquid batch fermentation. And the culture conditions were optimized as follows: seed age 10-12 h, inoculum 10%(v/v), and initial pH 6.5. Then culture medium compositions were optimized by single-factor and Response Surface Experiment. The results showed that under the conditions of corn starch cake 100 g/L, peptone 8.8 g/L, MgSCO40.42 g/L, MnSO4 0.05 g/L, CaCO310 g/L, the viable cells population reached 10.8×108 CFU/mL. Compared with the control, the viable cells population is increased by 160%.Based on the result of batch fermentation, the process of submerged fed-batch fermentation was investigated. The viable cells population and production intensity were further improved. Feeding medium was optimized as follows (g/L):corn starch cake 250, peptone 17.6, MgSO40.84, MnSO40.1, CaCO320. Then the fed-batch method was researched and the results showed that once fed 1/2 of the broth and fed medium every 16 h, not only the totle viable cells population and production intensity were the largest.The experiment of solid-state fermentation by Lactobacillus Rhamnosus was also carried out on the corn starch cake. Focused on the viable cells population, the culture conditions were optimized as follows:the ratio of corn starch cake and wheat bran,7:3; peptone,1%; initial water content,65%; dry material content,60 g/250 mL; inoculum,18%(v/m). In this condition, the viable cells population was reached 11×108 CFU/g dry material.