Screening and characterization of lactic acid bacterial strains possessing benzo[a]pyrene-removing ability
Date Issued
2015
Date
2015
Author(s)
Chiu, Yu-Tung
Abstract
Colorectal cancer (CRC) ranks the third most common malignant disease worldwide. The risk factors of CRC include the diet and lifestyle of people. Meat-related compounds, especially benzo(a)pyrene (BaP) is one of the best-characterised PAHs compound in the diet. Recently, studies have confirmed a correlation between probiotics and CRC that removing of carcinogens and mutagens has been considered as a possible mechanism in CRC prevention. The object of this study was to screen probiotic strains that have the BaP-removing ability. Then, the isolated strains exhibited high efficiency in removing BaP will be further evaluated for their functional properties and for its potential application as probiotic. As the results, the 28 bacterial strains were isolated from infant feces and then treated with 1 ppm BaP to analyze their BaP-removing ability. Three strains (YT 2, YT 5 and YT 17) had the best removing rate (97.66 %, 97.66 % and 97.79 %). The viability of the bacteria has significant effect on the removing of BaP. Cell walls of strains showed higher binding ability than heat-treated bacteria and intracellular extract. Therefore, we proposed that peptidoglycans played an important role in binding BaP. Antimutagenic activities of three strains were examined by Ames test. The results shows that the test strains didn’t have the cytotoxicity and mutagenicity against Salmonella typhimurium TA100 and the cultures incubated with potent mutagen BaP displayed high antimutagenic activities. After identification, YT 2 and YT 5 were classified as Enterococcus feacium, and YT 17 were Enterococcus feaclis. In the probiotic activity assay, all the test strains could survive in pH 2 solutions and grow in MRS broth containing 0.3% oxgall. In the Caco-2 cell adhesion assay, the test strains were able to adhere to Caco-2 cell. In conclusion, E. feacium YT 2, E. feacium YT 5 and E. feaclis YT 17 not only have the capable of removing BaP, but also possess antimutagenic activities, acid resistance, and bile salt tolerance ability. Therefore, E. feacium YT 2, E. feacium YT 5 and E. feaclis YT 17 have a potential to be applied in the human diet and animal feed.
Subjects
probiotic
lactic acid bacteria
carcinogen
benzo[a]pyrene
SDGs
Type
thesis
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