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Effect of Acetic Acid on Saccharomyces Carlsbergensis ATCC 6269 Batch Ethanol Production Monitored by Flow Cytometry.
MedLine Citation:
PMID:  22971830     Owner:  NLM     Status:  Publisher    
Bioethanol produced from lignocellulosic materials has been considered a sustainable alternative fuel. Such type of raw materials have a huge potential, but their hydrolysis into mono-sugars releases toxic compounds such as weak acids, which affect the microorganisms' physiology, inhibiting the growth and ethanol production. Acetic acid (HAc) is the most abundant weak acid in the lignocellulosic materials hydrolysates. In order to understand the physiological changes of Saccharomyces carlsbergensis when fermenting in the presence of different acetic acid (HAc) concentrations, the yeast growth was monitored by multi-parameter flow cytometry at same time that the ethanol production was assessed. The membrane potential stain DiOC(6)(3) fluorescence intensity decreased as the HAc concentration increased, which was attributed to the plasmic membrane potential reduction as a result of the toxic effect of the HAc undissociated form. Nevertheless, the proportion of cells with permeabilized membrane did not increase with the HAc concentration increase. Fermentations ending at lower external pH and higher ethanol concentrations depicted the highest proportions of permeabilized cells and cells with increased reactive oxygen species levels. Flow cytometry allowed monitoring, near real time (at-line), the physiological states of the yeast during the fermentations. The information obtained can be used to optimize culture conditions to improve bioethanol production.
Cláudia Freitas; Elisabete Neves; Alberto Reis; Paula C Passarinho; Teresa Lopes da Silva
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-9-13
Journal Detail:
Title:  Applied biochemistry and biotechnology     Volume:  -     ISSN:  1559-0291     ISO Abbreviation:  Appl. Biochem. Biotechnol.     Publication Date:  2012 Sep 
Date Detail:
Created Date:  2012-9-13     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8208561     Medline TA:  Appl Biochem Biotechnol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Laboratório Nacional de Energia e Geologia-LNEG, I.P, Unidade de Bioenergia, Estrada do Paço do Lumiar, 22, 1649-038, Lisboa, Portugal.
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