Publicação
Development of an improved propionibacterium for potential use as a nutraceutical towards the prevention - treatment of colorectal cancer
| Resumo: | Propionibacterium freudenreichii is a commercially important bacterium that is well-known for its role as ripening starter in the cheese industry and its probiotic potential. These bacteria may beneficially modulate the intestinal ecosystem and can exert anti-neoplastic effects, particularly against colorectal cancer (CRC), via the production of short chain fatty acids (SCFAs), namely acetate and propionate. Thus, propionibacteria can be envisaged as a potential nutraceutical towards the prevention/treatment of CRC. In that sense, the aim of this thesis was to develop strategies to enhance the production of SCFA by P. freudenreichii under the simulation of human colon environment, as well as to evaluate its effects on CRC cells. In order to optimize and characterize the production of SCFAs, acetate and propionate by P. freudenreichii, different culture media and different fermentation conditions were evaluated. Moreover, the SCFAs toxic concentrations for the bacterium were determined. Additionally, a digestive stress challenge and random mutagenesis of P. freudenreichii DSM 20271 were performed. Finally, the effect of the propionibacteria fermentation broth on CRC cells and the CRC cells conditioned medium on the growth and biotransformation performance of the bacteria were studied. The basal medium (BM) was found to be the best to produce SCFA by P. freudenreichii with high amounts of acetate and propionate being produced, mainly when supplemented with glycerol. However, the results obtained with the medium “mimicking the content of the human colon” (MCHC) were not favorable regarding SCFAs production. The adapted P. freudenreichii to digestive stress lost the ability to produce high amounts of SCFAs in yeast extract-lactate (YEL) and BM media, in particular propionate. Moreover, partial inhibition of the bacteria growth and SCFAs production occurred at the following concentrations of pure SCFAs: 4 g L-1 acetate; 3 g L-1 propionate; 6 g L-1 propionate; 1 g L-1 acetate and 3 g L-1 propionate. Pure acetate and propionate, as well as the bacterial fermentation broth inhibited the CRC cells RKO proliferation and promoted their accumulation in the sub-G1 phase of the cell cycle. In conclusion, the results gathered in this work suggest that the coculture of P. freudenreichii and CRC cells was found to be possible and favorable for the bacteria and that P. freudenreichii could potentially be used in the CRC prevention/treatment via their ability to produce SCFAs. |
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| Autores principais: | Casanova, Marta Alexandra Rodrigues |
| Assunto: | Ciências Naturais::Ciências Biológicas Ciências Médicas::Ciências da Saúde |
| Ano: | 2015 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Propionibacterium freudenreichii is a commercially important bacterium that is well-known for its role as ripening starter in the cheese industry and its probiotic potential. These bacteria may beneficially modulate the intestinal ecosystem and can exert anti-neoplastic effects, particularly against colorectal cancer (CRC), via the production of short chain fatty acids (SCFAs), namely acetate and propionate. Thus, propionibacteria can be envisaged as a potential nutraceutical towards the prevention/treatment of CRC. In that sense, the aim of this thesis was to develop strategies to enhance the production of SCFA by P. freudenreichii under the simulation of human colon environment, as well as to evaluate its effects on CRC cells. In order to optimize and characterize the production of SCFAs, acetate and propionate by P. freudenreichii, different culture media and different fermentation conditions were evaluated. Moreover, the SCFAs toxic concentrations for the bacterium were determined. Additionally, a digestive stress challenge and random mutagenesis of P. freudenreichii DSM 20271 were performed. Finally, the effect of the propionibacteria fermentation broth on CRC cells and the CRC cells conditioned medium on the growth and biotransformation performance of the bacteria were studied. The basal medium (BM) was found to be the best to produce SCFA by P. freudenreichii with high amounts of acetate and propionate being produced, mainly when supplemented with glycerol. However, the results obtained with the medium “mimicking the content of the human colon” (MCHC) were not favorable regarding SCFAs production. The adapted P. freudenreichii to digestive stress lost the ability to produce high amounts of SCFAs in yeast extract-lactate (YEL) and BM media, in particular propionate. Moreover, partial inhibition of the bacteria growth and SCFAs production occurred at the following concentrations of pure SCFAs: 4 g L-1 acetate; 3 g L-1 propionate; 6 g L-1 propionate; 1 g L-1 acetate and 3 g L-1 propionate. Pure acetate and propionate, as well as the bacterial fermentation broth inhibited the CRC cells RKO proliferation and promoted their accumulation in the sub-G1 phase of the cell cycle. In conclusion, the results gathered in this work suggest that the coculture of P. freudenreichii and CRC cells was found to be possible and favorable for the bacteria and that P. freudenreichii could potentially be used in the CRC prevention/treatment via their ability to produce SCFAs. |
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