Naseem A Gaur

Naseem A. Gaur
Group Leader- Yeast Biofuel Group
Integrative Biology Group
DBT-ICGEB Centre for Advanced Bio Energy Research
International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, 110 067 New Delhi, India.
E-mail: naseem@icgeb.res.in
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Education
Jawaharlal Nehru University /Jamia Millia Islamia University New Delhi, Ph.D., 2005
Jamia Millia Islamia University, New Delhi, M.Sc. (Bio-Sciences), 1999
Jamia Millia Islamia University, New Delhi, B.Sc. (Bio-Sciences), 1997

Career History
2012- Present: Research Scientist and Ramanujan Fellow, Synthetic Biology and Biofuel Group, DBT-ICGEB Center for Advance Bioenergy Research, ICGEB New Delhi, India
2010-2012: Research Fellow, National Institutes of Health (NIH), Bethesda, Maryland, USA
2007-2010: Postdoctoral Research Fellow, National Institutes of Health (NIH), Bethesda, Maryland, USA
2005- 2007: Post-doctoral Research Fellow, BWH, Harvard University, Boston, MA, USA

Research Interests
Heterologous pathways; yeast strains; biofuels; products synthesis; yeast libraries; improved fermentation; stress tolerance capabilities

Scientific Activity
Strain improvement for second generation biofuel production. Surface display of cellulolytic enzymes and consolidated bioprocessing. Proof reading deficient and error prone DNA polymerase δ mediated genetic manipulations in S. cerevisiae. Screening of S. cerevisiae strains with improved tolerance to pretreatment inhibitors and heat stress. Yeast metabolic pathway engineering and xylose fermentation.

Research Description
Synergistic saccharification, and direct fermentation of cellulosic biomass by an engineered yeast strain.
Cellulosic biomass (cellulose and hemicellulose), such as agricultural and forestry residues could be used as an ideally inexpensive and abundantly available source of sugar for fermentation into the sustainable transportation fuels. Three types of cellulolytic enzyme, endoglucanases (EG), cellobiohydrolases (CBH) and β-glucosidases (BGL) are required to convert biomass into fermentatble sugars. Endoglucanases are able to hydrolyze amorphous, soluble, and substituted celluloses randomly; Cellobiohydrolases are able to degrade crystalline cellulose and to produce cellobiose from reducing or nonreducing ends. These two types of enzymes act synergistically to degrade cellulose to cellobiose and other short cellooligosaccharides. β-Glucosidases hydrolyze cellobiose and other cellooligosaccharides produced by cellulases to glucose. Since, Saccharomyces cerevisiae cannot utilize cellulosic materials directly, these materials must first undergo saccharification to glucose before ethanol/ isobutanol production can take place. We are trying simultaneous and synergistic saccharification and fermentation of cellulosic biomass to ethanol/ isobutanol with the use of a recombinant yeast strain codisplaying cellulolytic enzymes on cell surafce, including EG5-a bifunctional chimeric enzyme made by Dr. S. Shams Yazdani via specific fusion of β-1, 4-Endoglucanase and β-1, 4-Glucodidase in our group recently.

Screening of Saccharomyces cerevisiae strains with improved tolerance to pretreatment inhibitors and elevated temperature. Weak acids, furan aldehydes, and phenolic compounds are liberated and/or generated together with fermentable sugars (e.g., glucose and xylose) from the hydrolysates of lignocellulosic biomass for ethanol production. These three main categories of lignocellulose-derived inhibitors reduce the growth rate and ethanol productivity of Saccharomyces cerevisiae by affecting cell viability, degrading DNA, and altering cell membrane properties. Increased temperature during fermentation is also rate limiting in ethanol production and cell viability. Our interest is to generate S. cerevisiae strains with improved performance in fermentation and tolerance to pretreatment inhibitors.  To select such kind of strains, we are generating S. cerevisiae mutant libraries, using Proof reading-deficient and error prone DNA polymerase δ.

Optimization of xylose fermentation into bioalcohols.
Xylose is the main pentose and second most abundant sugar in lignocellulosic feed stocks. Cost effective production of cellulosic bio-ethanol is dependent on complete and fast utilization of lignocellulosic biomass. Although, broadly used fermentative yeast Saccharomyces cerevisiae is one of the most effective ethanol-producing organisms from hexose sugars, it does not naturally ferment pentose (D-xylose). S. cerevisiae has been extensively engineered to incorporate an efficient D-xylose assimilation pathway. However, nearly all these reported xylose assimilation pathways in S. cerevisiae suffer from poor ethanol productivity, low xylose consumption rates, and poor cell growth. Poor enzyme activity of heterologous enzymes in S. cerevisiae and cofactor imbalance is considered the main reason for this. We are working to improve xylose assimilation pathways in S. cerevisiae by optimizing xylose assimilation pathway enzymes and cofactor requirements. 

Metabolic pathway engineering to increase the flux for isobutanol synthesis in S. cerevisiae.
Saccharomyces Cerevisiae naturally produces small amounts of higher alcohols through the degradation of amino acids, such as isobutanol is a side product of valine synthesis. We are expressing valine biosynthetic pathway enzymes Ilv2, Ilv5 and Ilv3 (relocating them from mitochondria to cytoplasm) under lexAOP-GAL1 promoter driven by leXA-VP16 (lexA DNA binding domain and viral protein16 activation domain) hybrid activator to increase the flux for isobutanol production. For optimal production of isobutanol, we are also screening for ketoisovalerate decarboxylase and alcohol dehydrogenase enzymes from different microbes.   

Publications
Gaur, N.A. Hasek, J., Brickner, D.G., Qiu, H., Zhang, F., Wong, C.M., Malcova, I., Vasicova, P., Brickner, J.H., Hinnebusch, A. G. 2013. Vps factors are required for efficient transcription elongation in budding Yeast. Genetics [Epub ahead of print]
Qiu, H. Hu, C., Gaur, N.A., Hinnebusch, A.G. 2012. Pol II CTD kinases Bur1 and Kin28 promote Spt5 CTR-independent recruitment of Paf1 complex. EMBO J 15, 3494-3505
Mousley, C.J. Yuan, P., Gaur, N.A., Trettin, K.D., Nile, A.H., Dewar, B., Deminoff, S., Herman, P.K., Hinnebusch, A. G., Macdonald, J.M., Bankaitis, V.A. 2012. A sterol binding protein integrates endosomal lipid metabolism with TOR signaling and nitrogen sensing. Cell 148, 702-715
Gaur, N.A. Zhang, F., Hasek, J., Kim, S., Qiu, H., Swanson, M. J., Hinnebusch, A.G., 2008. Disrupting Vesicular Trafficking at the Endosome Attenuates Transcriptional Activation by Gcn4. Mol Cell Biol 28, 6796-6818

Group members

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Farnaz Yusuf – PhD(MICROBIOLOGY)

Research Associate
E-mail : mattoofarnaz@gmail.com.
Hobby: Travelling & Reading.
Area of work: Molecular biology, Biocatalysis, Recombinant enzymes, Biotransformation.
My research work is focused on developing yeast for lignocellulosic ethanol production by metabolic engineering of xylose fermenting pathway. Two pathways are involved in xylose metabolism, a) Xylose reductase and xylitol dehydrogenase b) xylose isomerase.

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Sonakshi – M.Sc. (Biotechnology)

Junior Research Fellow
E-mail : sonakshi@gmail.com.
Hobby: Reading, listening music.
Area of work: Molecular Biology.
My Project is on the screening of high copy no. genomic DNA library of yeast and looking for the gene responsible for the high level tolerance to inhibitors like furfurals, etc,.

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Juhi Sharma- M.Sc. Microbiology

Junior Research Fellow
E-mail : taury.js04@gmail.com.
Hobby: Travelling, Reading novels.
Area of work: Synthetic Biology.
My work focuses on the expression and surface display of cellulolytic enzymes on S. cerevisiae for lignocellulosic biomass fermentation and bioethanol production.

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Sonam Kumari- M.Sc. Biotechnology

Pre Doctoral Fellow
E-mail : sonam@icgeb.res.in.
Hobby: Reading, Listening Music.
Area of work: Synthetic Biology & Biofuel
My work focuses on development of stress tolerant yeast by DNA polymerase mediated mutagenesis and role of transporters in efflux

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Mohit Kumar- M.Sc. Biotechnology

Junior Research Fellow
E-mail : mohitkumar@icgeb.res.in.
Hobby: Reading, Singing & Teaching.
Area of work: Synthetic Biology & Biofuel
My work focuses on the identification & Role of Xylose transporter in bioethanol production and status of epigenetic marker (DNA methylation & Histone ) in stress tolerant yeast

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Jakeer Shaik – M.Sc. Biotechnology

Junior Research Fellow
E-mail : shaik@icgeb.res.in.
Hobby: Biofuel Research & Development.
Area of work: Synthetic Biology.
I am working on isolation and characterization of novel cellulolytic enzymes using metagenomic approach.

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