| Summary: | 碩士 === 國立屏東科技大學 === 食品科學系 === 93 === Isolated strains of lactic acid bacteria (LAB) from commercial production and natural sources were tested for their efficiency in inhibiting Helicobacter pylori in this study. The No.2 strain of Lactobacillus paracasei was isolated from commercial fermented milk and the NO.26 strain of Lactobacillus plantarum was isolated from pickled vegetables. Two LAB strains could inhibited H. pylori BCRC 17023 and BCRC 17027 on the fermented milk plate and produced the inhibitory zones were 17 to 22 mm.
The main reasons of inhibition H. pylori were alive bacteria and produced lactic acid by L. paracasei that was incubated with the fermented milk could produce obvious inhibitory zone. In vitro test, fermented milk supernatant (FMS) of L. paracasei could kill 45% H. pylori and decreased 56% the urease activity in 2 hours. In addition, L. plantarum could excrete certain bacteriocins. In vitro test, neutral fermented milk supernatant (NFMS) of L. plantarum could kill 33 to 37% H. pylori and decreased 40 to 60% the urease activity in 2 hours.
Using FMS would be kill the H. pylori (8.8 Log CFU/mL) for 100% in 1 hour. But two LAB strains of FMS after, 30 min sterilized 100℃ lost the ability to inhibit H. pylori. In vivo, mice drank fermented milk for four week, the results showed that the H. pylori decreased to approximately 3 log cfu/ml and inhibited urease activity reaction in stomach. On the security of the LAB, after the mice of ICR and C57BL/6J two strains drank fermented milk 6 to 8 weeks, there were no obvious difference in the occurrence of physiological and pathological change.
Application of fermented milk, the ferment of L. paracasei was better in the skim milk and could directly fermented the skim milk, but unable to tolerate low pH value 3.0 and high concentration of 0.3% bile salts in the environmental of alimentary canal. When skim milk added more than 0.5% the yeast extract, L. plantarum were got better fermentation, survivability and adapted fine in the environmental of alimentary canal. While two LAB strains each other growth will be no inhibition condition and made fermented milk was 7.05 Log CFU/mL of alive LAB in store 60 days at 4℃.
The results showed that fermented milk in this research can prevent the infecting from H. pylori and do not have any toxic for the security in eating, may be used for making fermented milk and possess good shelf life.
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