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Enzyme Research
Volume 2015, Article ID 573721, 10 pages
Research Article

Immobilization of Papain on Chitin and Chitosan and Recycling of Soluble Enzyme for Deflocculation of Saccharomyces cerevisiae from Bioethanol Distilleries

1Department of Biological Science, University of State of São Paulo (UNESP), 19806-900 Assis, SP, Brazil
2Food Engineering Faculty, State University of Campinas (UNICAMP), 13083-970 Campinas, SP, Brazil

Received 3 September 2014; Revised 28 November 2014; Accepted 28 November 2014

Academic Editor: Denise Freire

Copyright © 2015 Douglas Fernandes Silva et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Supplementary Material

Mechanism of yeast and bacteria cells flocculation: The flocculation mechanism between cells of contaminating bacteria and yeasts in fuel ethanol fermentation is associated with the physical contact between the cell wall of these microorganisms. There is an optimum relationship between the amount of bacteria and yeast cells needed to cause cells flocculation. According Yokoya and Oliva-Neto [7] by microscopic count this ratio is 4.8 (bacteria/yeast), which explains the sudden appearance of yeast flocculation in fuel ethanol production industries, when there is an increase in bacterial contamination by mainly Lactobacillus fermentum. Amino acid residues on surface of Lactobacillus fermentum cell wall and carbohydrate residues on yeast cell wall are responsible for the development of yeast cells flocculation. Some reactions with specific reagent which modified proteins indicated the indole group of tryptophan and phenolic hydroxyl group of tyrosine must be present on the bacterial cell surface for the flocculation to occur. The residues of mannan on the cell surface of yeast are responsible for this binding [6]. Therefore, protein factors associated with minerals such as Ca+2 [5], as well as mannans, have been proved to be involved in the process of flocculation.

  1. Supplementary Materials