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Selective suppression of bacterial contaminants by process conditions during lignocellulose based yeast fermentations

BACKGROUND: Contamination of bacteria in large-scale yeast fermentations is a serious problem and a threat to the development of successful biofuel production plants. Huge research efforts have been spent in order to solve this problem, but additional ways must still be found to keep bacterial conta...

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Autores principales: Albers, Eva, Johansson, Emma, Franzén, Carl Johan, Larsson, Christer
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2011
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3284421/
https://www.ncbi.nlm.nih.gov/pubmed/22185398
http://dx.doi.org/10.1186/1754-6834-4-59
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author Albers, Eva
Johansson, Emma
Franzén, Carl Johan
Larsson, Christer
author_facet Albers, Eva
Johansson, Emma
Franzén, Carl Johan
Larsson, Christer
author_sort Albers, Eva
collection PubMed
description BACKGROUND: Contamination of bacteria in large-scale yeast fermentations is a serious problem and a threat to the development of successful biofuel production plants. Huge research efforts have been spent in order to solve this problem, but additional ways must still be found to keep bacterial contaminants from thriving in these environments. The aim of this project was to develop process conditions that would inhibit bacterial growth while giving yeast a competitive advantage. RESULTS: Lactic acid bacteria are usually considered to be the most common contaminants in industrial yeast fermentations. Our observations support this view but also suggest that acetic acid bacteria, although not so numerous, could be a much more problematic obstacle to overcome. Acetic acid bacteria showed a capacity to drastically reduce the viability of yeast. In addition, they consumed the previously formed ethanol. Lactic acid bacteria did not show this detrimental effect on yeast viability. It was possible to combat both types of bacteria by a combined addition of NaCl and ethanol to the wood hydrolysate medium used. As a result of NaCl + ethanol additions the amount of viable bacteria decreased and yeast viability was enhanced concomitantly with an increase in ethanol concentration. The successful result obtained via addition of NaCl and ethanol was also confirmed in a real industrial ethanol production plant with its natural inherent yeast/bacterial community. CONCLUSIONS: It is possible to reduce the number of bacteria and offer a selective advantage to yeast by a combined addition of NaCl and ethanol when cultivated in lignocellulosic medium such as wood hydrolysate. However, for optimal results, the concentrations of NaCl + ethanol must be adjusted to suit the challenges offered by each hydrolysate.
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spelling pubmed-32844212012-02-23 Selective suppression of bacterial contaminants by process conditions during lignocellulose based yeast fermentations Albers, Eva Johansson, Emma Franzén, Carl Johan Larsson, Christer Biotechnol Biofuels Research BACKGROUND: Contamination of bacteria in large-scale yeast fermentations is a serious problem and a threat to the development of successful biofuel production plants. Huge research efforts have been spent in order to solve this problem, but additional ways must still be found to keep bacterial contaminants from thriving in these environments. The aim of this project was to develop process conditions that would inhibit bacterial growth while giving yeast a competitive advantage. RESULTS: Lactic acid bacteria are usually considered to be the most common contaminants in industrial yeast fermentations. Our observations support this view but also suggest that acetic acid bacteria, although not so numerous, could be a much more problematic obstacle to overcome. Acetic acid bacteria showed a capacity to drastically reduce the viability of yeast. In addition, they consumed the previously formed ethanol. Lactic acid bacteria did not show this detrimental effect on yeast viability. It was possible to combat both types of bacteria by a combined addition of NaCl and ethanol to the wood hydrolysate medium used. As a result of NaCl + ethanol additions the amount of viable bacteria decreased and yeast viability was enhanced concomitantly with an increase in ethanol concentration. The successful result obtained via addition of NaCl and ethanol was also confirmed in a real industrial ethanol production plant with its natural inherent yeast/bacterial community. CONCLUSIONS: It is possible to reduce the number of bacteria and offer a selective advantage to yeast by a combined addition of NaCl and ethanol when cultivated in lignocellulosic medium such as wood hydrolysate. However, for optimal results, the concentrations of NaCl + ethanol must be adjusted to suit the challenges offered by each hydrolysate. BioMed Central 2011-12-20 /pmc/articles/PMC3284421/ /pubmed/22185398 http://dx.doi.org/10.1186/1754-6834-4-59 Text en Copyright ©2011 Albers et al; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research
Albers, Eva
Johansson, Emma
Franzén, Carl Johan
Larsson, Christer
Selective suppression of bacterial contaminants by process conditions during lignocellulose based yeast fermentations
title Selective suppression of bacterial contaminants by process conditions during lignocellulose based yeast fermentations
title_full Selective suppression of bacterial contaminants by process conditions during lignocellulose based yeast fermentations
title_fullStr Selective suppression of bacterial contaminants by process conditions during lignocellulose based yeast fermentations
title_full_unstemmed Selective suppression of bacterial contaminants by process conditions during lignocellulose based yeast fermentations
title_short Selective suppression of bacterial contaminants by process conditions during lignocellulose based yeast fermentations
title_sort selective suppression of bacterial contaminants by process conditions during lignocellulose based yeast fermentations
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3284421/
https://www.ncbi.nlm.nih.gov/pubmed/22185398
http://dx.doi.org/10.1186/1754-6834-4-59
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