Screening Of Lactobacillus For Efficient Cholesterol-degrading And Its Application In Fermented Milk

26 Lactobacillus acidophilus and 19 Lactobacillus were studied in the experiments. The quantity of the Cholesterol-degrading in MRS-CHOL medium was used to analyze their cholesterol-reducing ability, then bile-tolerance and acid-tolerance. The results show that all strains could remove cholesterol from media and removal rates of in which 6 strains (WE43-1-2, WE57-1, 1-3, 1-4, 1-8, 2-2) were more than 40%.Meanwhile , these 6 strains had high removal effectiveness. As a result, these 6 strains were screened for their excellent cholesterol-reducing ability. 1-3, 1-4, 1-8, and 2-2 were Lactobacillus acidophilus. WE43-1-2 and WE57-1, according to their morphological, physiological and biochemical properties, including chemical characteristics, were identified to Lactobacillus agilis and Lactobacillus casei subsp casei. Acid-tolerance and bile tolerance were tested and compared with reducing cholesterol ability of these 6 strains respectively. The bile-tolerance and acid-tolerance were varied from strain to strain.Among 6 strains, 2-2 demonstrated higher ability of removal cholesterol, acid-tolerance and bile-tolerance than other strains. So that 2-2 was selected as the optimal strain. The culture A includes streptococcus thermophilic and lactobaccillus bulgaricus and the culture B includes streptococcus thermophilic and 2-2.The reducing cholesterol ability in fermented milk of A and B were compared under 42℃constant temperature 4-6h. The results indicate that Variation between two cultures in the ability to decrease cholesterol in fermented milk was significantly different(P<0.05). The cholesterol-degrading rates from fermented milk by the two cultures were 5.39% and 14.30% respectively. 2-2 strain could be applied to the production of fermented low-cholesterol milk.