| Summary: | 碩士 === 國立陽明大學 === 生化暨分子生物研究所 === 99 === The aims of this study are to isolate lactic acid bacteria (LAB) from human breast milk and infant feces, then identify these bacteria, and evaluate the probiotic properties of them. Four human breast milk samples and feces samples from six infants were collected. ROGOSA agar plate and TOS-p with mupirocin agar plate were used to isolate lactobacillus and bifidobacterium respectively. After these samples were analysed by RAPD-PCR and gene identification, the results showed that the bacteria isolated from our samples included lactobacillus, bifidobacterium, and Enterococcus which are the most common used as probiotics.
Lactic acid bacteria have many advantages for human being, lower serum cholesterol for example. We used BSH (bile salt hydrolase) activity assay and in vitro cholesterol lowering test to assess the cholesterol lowering ability of LABs. The results showed that Lactobacillus casei (F2-9.1, F2-12.2, F3-26.3), Bifidobacterium longum (B2-9), Enterococcus hirae (B1-6B, B2-2, B2-11, B4-2.3A, F2-11.2, F2-14.3, F5-2.1, F5-4, F5-12), and Enterococcus faecium (F3-26.1) have BSH activity and the cholesterol lowering ability.
Two of the most important probiotic properties are resistance to gastric acid and bile toxicity, so that they will be able to pass through the gastrointestinal tract (GIT) and have the chance to colonize in the GIT. In the acid tolerance test result, Lactobacillus plantarum (F2-1.1), Lactobacillus casei (F2-9.1, F2-10.2, F2-12.1), Lactobacillus rhamnosus (F3-12), Enterococcus hirae (B1-6B, B3-10.1, B3-12.2, B3-20.1, B3-20.2, B4-14.1, F2-11.2), and Enterococcus faecium (F4-12.3) had the good acid resistance. In the bile salt tolerance test result, Lactobacillus casei (F3-26.1, B3-7.1), Lactobacillus paracasei(F2-3.1), Bifidobacterium longum(F3-9.1, F3-14.1, F3-15.1), Enterococcus hirae(F2-10.1, F5-16.1, B3-20.2) had good bile salt tolerance.
Based on these in vitro analyses, Lactobacillus casei (F3-26.2), Bifidobacterium longum (B2-9), and Enterococcus hirae (F2-11.2) are here proposed as new probiotic candidates.
|
|---|
