指導論文
| 論文標題 | Characterization and Identification of Lactic Acid Bacteria Isolated from Fresh Milk (市售鮮乳乳酸菌之分離.鑑定及特性探討) |
| 研究生 | Ya-Ling Liu (劉亞玲) |
| 指導教授 | Jiau-hua Chen(陳椒華) 、Shu-jen Wang(王淑珍) |
| 摘要 | The lactic acid bacteria are widely distributed in the nature, and have been greatly used for a long time since they have useful characteristics. In recent years, the lactic acid bacteria were also applied in the development of healthy food. In this study, eight lactic acid bacteria-like strains were isolated from the fresh milk, and later it has been proved that these strains were lactic acid bacteria-like through examination. These bacteria were all positive in skim milk curdling, the same as in Gram stain but negative in catalase reaction. These eight lactic acid bacteria-like strains were further identified with API 50 CHL test kit. This experimentation tells us these strains have high similarities, which are all with Lactobacillus paracasei subsp. paracasei , Lactobacillus brevis and Pediococcus pentosaceus. In order to identify the phylogeny hierarchy of the isolated bacteria, the 16S rRNA genes were identified in four strains. The amplification of the 16S rRNA gene were subjected by PCR tests with universal primers, and the PCR products were subjected to 16S rDNA sequencing analysis. The 16S rDNA sequences from the four strains were compared with the reference strains which were held in GenBank. The above show high similarities and the four isolates were Lactobacillus sp. L1, Pediococcus acidilactici Lac1, Enterococcus faecium M43 and Enterococcus sp. M51. Moreover, further analyses were done to identify if the feasibility of the four lactic acid bacteria can be probiotics strains. The strain capabilities of tolerance to gastric juice and resistance to bile salt were done. The results showed that the four lactic acid bacteria can be both tolerant to gastric juice and resistant to bile salts. The antibiotic susceptibility and inhibition to pathogenic bacteria were tested. These four lactic acid bacteria were resistant to kanamycin and gentamicin, and no apparent inhibitions to pathogenic bacteria were found. |
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