Studies On Isolation And Identification Of Lactobcillus Acidophilus And Its Characteristics From Koumiss In Xinjiang

Lactobacillacs acidophilus is an important microorganism in human intestinal tract. When there exist certain number of Lactobacillus acidoplzilus in intestinal tract, they play an important role. Lactobacillus acidophilus is considered as the third generation starter for yogurt. Lactobacillus acidophilus isolated from the Xinjiang region of koumiss, and there are few reports on the study about physiological characteristics of Lactobacillus acidophilus.In this study, Lactobacillus strains were isolated from the samples collected traditional koumiss in Urumqi, Xinjiang Shuixigou, Yili Prefecture and the sold yogurt. There were four Lactobacillus acidophilus strains through molecularly biological identification. This study is aim to provide Lactobacillus acidophilus strains with strong growth capacity, high active number and strong acid-producing ability for yogurt.Besides, this study explored the growth characteristics of Lactobacillus acidophilus in yogurt, providing a theoretical basis and a scientific basis for industrialized production of the yogurt.By comparing the biological characteristics of the four strains including the growth curve, acid-producing ability, gastric acid-resistant capacity, bile-resistant capacity,resistance to osmotic pressure and antibiotic resistance. This study choosed Lactobacillus acidophilus G14has strong acid-resistant, resistance to osmotic pressure and antibiotic resistance; Lactobacillus acidophilus G13has strong bile-resistant capacity; and Lactobacillus acidophilus S22has strong resistance to osmotic pressure and bile-resistant capacity; the biological characteristics of strain L19compared to other strains of this bacteria.After activated in the growth culture for three times, Lactobacillus acidophilus G13, S22and G14was inoculated in the yogurt. After fermented for24hours at37℃, the growth curve in the yogurt is0～6h in the growth lag phase after inoculation, during the6～18h is logarithmic phase, during the18～24h is stable phase. Lactobacillus acidophilus G14has strong acid-producing ability, after fermented for24hours at37℃, titratable acidity94.77°T, pH4.3. The order of these three Lactobacillus acidophilus has to reach the end of fermentation G14> S22> G13. During4℃cold storage, pH and titratable acidity trend flat, strains tested postacidification is not obvious. In16days, strain G13, S22and G14still has a high survival rate, respectively were0.93%,1.05%,3.65%, viability of the order, followed by G14>S22>G13.