Fermentable and non-fermentable sugars: A simple experiment of anaerobic metabolism

Authors

  • Tony P. Paulino,

    1. Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, SP, Brazil
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    • Recipient of a Ph.D. fellowship from the Comissao de Aperfeiçoamento de Pessoal de Nival Superior.

  • Mauro Cardoso Jr,

    1. Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, SP, Brazil
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  • Giuliana C. M. Bruschi-Thedei,

    1. Instituto de Ciências Biológicas e da Saúde, Universidade de Uberaba, 38055-500 Uberaba, MG, Brazil
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  • Pietro Ciancaglini,

    1. Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, SP, Brazil
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  • Geraldo Thedei Jr

    Corresponding author
    1. Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, SP, Brazil
    • Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, SP, Brazil
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Abstract

The main objective of this class experiment is to show the time-dependent consumption of a fermentable sugar (glucose) in the presence and absence of a non-fermentable sugar (xylose) by bacteria in anaerobic conditions. The observation of the pH decrease due to acid production and the turbidity increase as a result of cell multiplication, both in function of time, enables an interesting discussion regarding the metabolic pathways and the products of anaerobic fermentation of carbohydrates. Also the time-dependent disappearance of glucose due to its metabolic consumption is compared with the non-disappearance of xylose and permits a discussion of the function of glycolysis and pentose phosphate pathways as metabolic routes.

This work was supported by the Universidade de Uberaba, Fundaçao de Amparo à Pesquisa do Estado de São Paulo, and Conselho Nacional de Pesquisas (Brazil).

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