Identification And Probiotic Potential Evaluation Of Lactobacillus Kefiri KL22

Lactic acid bacteria is a kind of bacteria which is gram positive,non-spore,anaerobic or facultative anaerobic bacteria.It has functions such as regulating intestinal flora and improving human immunity.Lactobacillus in lactic acid bacteria contains more than 50 species,most of which have the function of regulating intestinal flora and improving human immunity,and Lactobacillus casei,Lactobacillus plantarum and Lactobacillus bulgaricus have been used in the food processing industry such as dairy products.However L.kefiri has not yet been listed in the list of national edible lactic acid bacteria.Due to its immunomodulation,inhibition of pathogenic bacteria,and lowering serum cholesterol,it has been widely concerned.The strain KL22 was isolated from Poland KG,and its functional and fermentation properties were preliminarily discussed in order to provide theoretical basis for its development and utilization.The following conclusions were obtained:(1)A strain isolated from Polish Kefir granules,combined with morphological identification,biochemical test identification and molecular biological identification,confirmed that the strain was L.kefiri,named KL22.The antibiotic susceptibility test confirmed that strain KL22 showed resistance to ciprofloxacin,vancomycin,co-trimoxazole and oxacillin,was moderately sensitive to tetracycline,and was sensitive to the remaining 25 antibiotics.(2)KL22 has strong acid resistance and certain ability to resist bile salts.The hydrophobicity test,self-cohesion test and Caco-2 cell adhesion test showed that KL22 had certain adhesion ability,when the concentration of bacterial solution was 108cfu/ml,the number of adhesion is significantly higher than other concentrations,was 24.59 cells per cell.KL22 has scavenging ability for OH-,O2-and DPPH,and the inactivated group's scavenging ability of DPPH is as high as 72.02%.The strain KL22 also has certain regulatory ability to IL-8,TNF-? and h BD-2,indirectly regulate the immune system and improve the host immune ability.The results of cholesterol lowering test in vitro showed that the strain kl22 had a certain ability of lowering cholesterol,and the degradation rate of cholesterol of live kl22 was 52.94 after 48 h.(3)The study on the fermentation characteristics of strain kl22 showed that it has certain autolysis and acid production ability.The optimum fermentation sugar is maltose,and the optimum fermentation temperature is 37 °C.In addition,It also has the characteristics of high viable bacteria in the shelf life.Finally,five kinds of basic starter were selected to co-ferment with KL22.It was found that the yoghurt fermented with basic starter 1 had good taste and good p H,acidity,viscosity and water holding capacity.