Screening And Application Of Methionine-yielding Probiotics

Probiotics are microbial organisms, playing beneficial affect by improving the balance of microbial in host, they can increase the health level and health condition. Probiotics can be uses and fed directly to human and animals. It can improve the equilibrium of flora and reduce harmful substance in animal intestines, increase the immuno-competence of animal body, promote animal's growth and development and improve animal's performance trait. It is a new-style green feed additive.Methionine is one of the limiting essential amino acids and it is one of the amino acids which is essential for the synthesis of animal protein in internal of animal and it can provide protein nutrition. Methionine can balance the absorption of amino acids in small intestine and it is a desirable feed additive. The purpose of this experiment is to select several strains of methionine -yielding probiotics from the isolated strains.In this experiment, 48 kinds of strains were isolated and cultured from dough of bread, twisted, buns, section cake, Russia bread, rice wine, yeast of distillate spirit, and strains supplied by laboratory. Methionine in these fermentation broths was detected by high efficiency liquid chromatography. Methionine-yielding strains were selected and identified by 16SrDNA, blast analysis, and species-specific primers PCR. At last, fermenting liquor of high-yielding methionine strains as a probiotic additive was used in dairy cow feed to explore its influence on cow's production trait.Two methionine-yielding strains were isolated, cultured and screened by conventional method, such as plate isolation and observation by light microscope, and high performance liquid chromatography. Identification has been made by 16S rDNA, blast analysis, and species-specific primers PCR.The results showed that these strains were bacillus natto and Bacillus subtilis and the amount of methionine in the fermentation broths of them was 21.08g/L and 19.38g/L respectively. Fermenting liquor of bacillus natto as a probiotic additive was used in dairy cow feed, the cow's milk production was increased by 4.43%, content percentage of milk protein by 1.04%, the lactose and dry matter in milk by 0.89% and 0.61%, respectively, the milk fat by 1.06%. Result of statistical analysis showed that the difference of content percentage of milk protein was predominant (P<0.05) and the difference of the lactose, dry matter in milk and milk fat were extremely predominant (P<0.01). The result of this experiment showed that the amount of methionine in the fermentation broth of bacillus natto was higher than others and it might be the reason of increasement of the production and qualitative of milk.