Strain development of yeasts for efficient alcoholic fermentation utilizing xylose

Simple item page
dc.contributor.advisorKalra, K. L.
dc.contributor.authorSushma Gurumayum
dc.date.accessioned2016-12-05T15:44:57Z
dc.date.available2016-12-05T15:44:57Z
dc.date.issued2010
dc.description.abstractTwo strains of yeasts, Saccharomyces cerevisiae G and Pachysolen tannophilus MTCC1077 were used to develop improved strains of yeasts for efficient alcoholic fermentation utilizing xylose as carbon source by means of mutagenesis and protoplast fusion. Mutagenesis of xylose fermenting yeast, P. tannophilus MTCC1077 using physical mutagen, UV rays gave rise to 103 ethanol negative variants with the inability to use ethanol as carbon source for growth. The parent P tannophilus MTCC1077 was found to give a maximum ethanol yield of 0.339g/g with a corresponding fermentation efficiency of 66.47% from 20g/l xylose when fermentation was carried out at 30ºC at a pH of 5.0 with inoculum of 6% and an aeration of 100rpm. Two ethanol negative variants UVmut 62 and UVmut 41 gave ethanol yields significantly higher than the parent strain. UVmut 41 showed highest yield of ethanol of 0.350g/g with a fermentation efficiency of 68.53% while UVmut 62 gave a yield of 0.347 g/g with a fermentation efficiency of 67.92%. Mutagenesis of xylose fermenting yeast, P. tannophilus MTCC1077 using chemical mutagen, ethylmethanesulfonate (EMS) gave rise to 102 ethanol negative variants with the inability to use ethanol as carbon source for growth. Three ethanol negative variants EMSmut14, EMSmut39 and EMSmut26 showed significantly higher ethanol producing capacity than the parent strain. EMSmut26 gave the highest ethanol yield of 0.364g/g with a fermentation efficiency of 71.32% followed by EMSmut39 and EMSmut14 giving a yield of 0.350g/g and 0.346g/g respectively. Protoplast isolation rates of 99% for S. cerevisiae and 97% for P. tannophilus achieved with action of lyticase enzyme (0.08mg/ml) on cells for 60min at 30°C with 0.8M sorbitol, 1mM EDTA and 10mM Tris buffer at pH 7.5. Protoplast fusion was obtained when cells were treated for 30min with chemical fusogen, polyethyleneglycol (PEG mol wt. 6000) and highest protoplast regeneration frequency of 21% was obtained with 35% PEG and 0.8M sorbitol at 30ºC. Two fusants were able to produce ethanol from a mixture of glucose and xylose. Parent S. cerevisiae gave an ethanol yield of 0.430g/g with a fermentation efficiency of 84.21%. FUS1 giving a yield of 0.244g/g with a fermentation efficiency of 47.82% while FUS2 gave a yield of 0.273g/g with fermentation efficiency of ethanol at 72hr of fermentation. Scanning electron microscopy (SEM) study of parent strains and fusants revealed differences in the cell surface and also in budding pattern as compared to that seen with either of the individual parent strains. DNA contents of the two fusants were larger than that of any single parental strains, suggesting that these fusants have inherited genetic material from both parental strains.en_US
dc.identifier.urihttp://krishikosh.egranth.ac.in/handle/1/89217
dc.language.isoenen_US
dc.publisherPunjab Agricultural University Ludhianaen_US
dc.research.problemStrain development of yeasts for efficient alcoholic fermentation utilizing xyloseen_US
dc.subMicrobiology
dc.these.typePh.D
dc.titleStrain development of yeasts for efficient alcoholic fermentation utilizing xyloseen_US
dc.typeThesisen_US
Files
Original bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
SUSHMA GURUMAYUM FINAL THESIS.pdf
Size:
1.05 MB
Format:
Adobe Portable Document Format
Description:
MICROBIOLOGY
Download
License bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
license.txt
Size:
2.28 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
Thesis