Limits...
Identification of furfural resistant strains of Saccharomyces cerevisiae and Saccharomyces paradoxus from a collection of environmental and industrial isolates.

Field SJ, Ryden P, Wilson D, James SA, Roberts IN, Richardson DJ, Waldron KW, Clarke TA - Biotechnol Biofuels (2015)

Bottom Line: Furthermore, ethanol production in this strain did not appear to be inhibited by furfural, with the highest ethanol yield observed at 3.0 mg ml(-1) furfural.Although furfural resistance was not found to be a trait specific to any one particular lineage or population, three of the strains were isolated from environments where they might be continually exposed to low levels of furfural through the ongoing natural degradation of lignocelluloses, and would therefore develop elevated levels of resistance to these furan compounds.Thus, these strains represent good candidates for future studies of genetic variation relevant to understanding and manipulating furfural resistance and in the development of tolerant ethanologenic yeast strains for use in bioethanol production from lignocellulose processing.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of East Anglia, Norwich, NR4 7JN UK.

ABSTRACT

Background: Fermentation of bioethanol using lignocellulosic biomass as a raw material provides a sustainable alternative to current biofuel production methods by utilising waste food streams as raw material. Before lignocellulose can be fermented, it requires physical, chemical and enzymatic treatment in order to release monosaccharides, a process that causes the chemical transformation of glucose and xylose into the cyclic aldehydes furfural and hydroxyfurfural. These furan compounds are potent inhibitors of Saccharomyces fermentation, and consequently furfural tolerant strains of Saccharomyces are required for lignocellulosic fermentation.

Results: This study investigated yeast tolerance to furfural and hydroxyfurfural using a collection of 71 environmental and industrial isolates of the baker's yeast Saccharomyces cerevisiae and its closest relative Saccharomyces paradoxus. The Saccharomyces strains were initially screened for growth on media containing 100 mM glucose and 1.5 mg ml(-1) furfural. Five strains were identified that showed a significant tolerance to growth in the presence of furfural, and these were then screened for growth and ethanol production in the presence of increasing amounts (0.1 to 4 mg ml(-1)) of furfural.

Conclusions: Of the five furfural tolerant strains, S. cerevisiae National Collection of Yeast Cultures (NCYC) 3451 displayed the greatest furfural resistance and was able to grow in the presence of up to 3.0 mg ml(-1) furfural. Furthermore, ethanol production in this strain did not appear to be inhibited by furfural, with the highest ethanol yield observed at 3.0 mg ml(-1) furfural. Although furfural resistance was not found to be a trait specific to any one particular lineage or population, three of the strains were isolated from environments where they might be continually exposed to low levels of furfural through the ongoing natural degradation of lignocelluloses, and would therefore develop elevated levels of resistance to these furan compounds. Thus, these strains represent good candidates for future studies of genetic variation relevant to understanding and manipulating furfural resistance and in the development of tolerant ethanologenic yeast strains for use in bioethanol production from lignocellulose processing.

No MeSH data available.


Related in: MedlinePlus

Concentration of glucose (squares) and furfural (triangles) present in wheat straw hydrolysates made as described in the ‘Methods’ section with an increasing concentration of initial straw.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4389715&req=5

Fig2: Concentration of glucose (squares) and furfural (triangles) present in wheat straw hydrolysates made as described in the ‘Methods’ section with an increasing concentration of initial straw.

Mentions: To investigate the cause of the decreased cell growth on wheat straw hydrolysate, S. cerevisiae NCYC 2826 was grown on hydrolysate made using 5%, 10%, 15% and 20% starting straw concentration and supplemented with 2.3 mg ml−1 urea. Figure 1B shows that as the initial straw concentration increased, the lag phase of growth also increased to 20 h at an initial straw concentration of 20%. The final OD also increased as straw concentration increased, due to the increased concentrations of released glucose. The increased lag phase is characteristic of inhibition of growth by furan compounds often present in straw hydrolysates [14]. Analysis of the furan content of the hydrolysate showed that HMF content was negligible (data not shown) but the concentration of furfural present increased with initial straw concentration reaching 0.5 mg ml−1 at 20% initial straw content (Figure 2). These data suggest that growth of S. cerevisiae NCYC 2826 on wheat straw hydrolysate is limited by the concentration of furfural present in the hydrolysate.Figure 2


Identification of furfural resistant strains of Saccharomyces cerevisiae and Saccharomyces paradoxus from a collection of environmental and industrial isolates.

Field SJ, Ryden P, Wilson D, James SA, Roberts IN, Richardson DJ, Waldron KW, Clarke TA - Biotechnol Biofuels (2015)

Concentration of glucose (squares) and furfural (triangles) present in wheat straw hydrolysates made as described in the ‘Methods’ section with an increasing concentration of initial straw.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4389715&req=5

Fig2: Concentration of glucose (squares) and furfural (triangles) present in wheat straw hydrolysates made as described in the ‘Methods’ section with an increasing concentration of initial straw.
Mentions: To investigate the cause of the decreased cell growth on wheat straw hydrolysate, S. cerevisiae NCYC 2826 was grown on hydrolysate made using 5%, 10%, 15% and 20% starting straw concentration and supplemented with 2.3 mg ml−1 urea. Figure 1B shows that as the initial straw concentration increased, the lag phase of growth also increased to 20 h at an initial straw concentration of 20%. The final OD also increased as straw concentration increased, due to the increased concentrations of released glucose. The increased lag phase is characteristic of inhibition of growth by furan compounds often present in straw hydrolysates [14]. Analysis of the furan content of the hydrolysate showed that HMF content was negligible (data not shown) but the concentration of furfural present increased with initial straw concentration reaching 0.5 mg ml−1 at 20% initial straw content (Figure 2). These data suggest that growth of S. cerevisiae NCYC 2826 on wheat straw hydrolysate is limited by the concentration of furfural present in the hydrolysate.Figure 2

Bottom Line: Furthermore, ethanol production in this strain did not appear to be inhibited by furfural, with the highest ethanol yield observed at 3.0 mg ml(-1) furfural.Although furfural resistance was not found to be a trait specific to any one particular lineage or population, three of the strains were isolated from environments where they might be continually exposed to low levels of furfural through the ongoing natural degradation of lignocelluloses, and would therefore develop elevated levels of resistance to these furan compounds.Thus, these strains represent good candidates for future studies of genetic variation relevant to understanding and manipulating furfural resistance and in the development of tolerant ethanologenic yeast strains for use in bioethanol production from lignocellulose processing.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of East Anglia, Norwich, NR4 7JN UK.

ABSTRACT

Background: Fermentation of bioethanol using lignocellulosic biomass as a raw material provides a sustainable alternative to current biofuel production methods by utilising waste food streams as raw material. Before lignocellulose can be fermented, it requires physical, chemical and enzymatic treatment in order to release monosaccharides, a process that causes the chemical transformation of glucose and xylose into the cyclic aldehydes furfural and hydroxyfurfural. These furan compounds are potent inhibitors of Saccharomyces fermentation, and consequently furfural tolerant strains of Saccharomyces are required for lignocellulosic fermentation.

Results: This study investigated yeast tolerance to furfural and hydroxyfurfural using a collection of 71 environmental and industrial isolates of the baker's yeast Saccharomyces cerevisiae and its closest relative Saccharomyces paradoxus. The Saccharomyces strains were initially screened for growth on media containing 100 mM glucose and 1.5 mg ml(-1) furfural. Five strains were identified that showed a significant tolerance to growth in the presence of furfural, and these were then screened for growth and ethanol production in the presence of increasing amounts (0.1 to 4 mg ml(-1)) of furfural.

Conclusions: Of the five furfural tolerant strains, S. cerevisiae National Collection of Yeast Cultures (NCYC) 3451 displayed the greatest furfural resistance and was able to grow in the presence of up to 3.0 mg ml(-1) furfural. Furthermore, ethanol production in this strain did not appear to be inhibited by furfural, with the highest ethanol yield observed at 3.0 mg ml(-1) furfural. Although furfural resistance was not found to be a trait specific to any one particular lineage or population, three of the strains were isolated from environments where they might be continually exposed to low levels of furfural through the ongoing natural degradation of lignocelluloses, and would therefore develop elevated levels of resistance to these furan compounds. Thus, these strains represent good candidates for future studies of genetic variation relevant to understanding and manipulating furfural resistance and in the development of tolerant ethanologenic yeast strains for use in bioethanol production from lignocellulose processing.

No MeSH data available.


Related in: MedlinePlus