Resume

• 2004

  Hindi

  Doctor of Philosophy (PhD)

  “Synergy of Protein and Genome Engineering for Fuels and Chemicals Production”\n•\tAdvisor: Prof. Huimin Zhao\n•\tCreated tools for genome and metabolic engineering of E. coli and yeast\n•\tEngineered proteins (directed evolution) and microbes (metabolic engineering) for\n\tBiofuel (n-butanol) biosynthesis in yeast\n\tXylitol production from hemicellulose using E. coli\n•\tOptimized fermentation conditions for xylitol production\n•\tScreened protein crystallization conditions for\n\tL-Xylulose Reductase from Neurospora crassa\n\tPhosphite Dehydrogenase from Pseudomonas stutzeri

  Chemical Engineering

  American Institute of Chemical Engineers (AIChE)\nAmerican Chemical Society (ACS)

  University of Illinois at Urbana-Champaign

• 1999

  Bachelor of Science (BS)

  “Semiconductor lattice defects”\n•\tResearch Assistant

  Department of Chemical & Biomolecular Engineering\n•\tAdvisor: Prof. Paulette Clancy\n•\tRan simulations and analyzed results to study the formation and stability of lattice defects such as interstitials and a phenomenon known as “bond defect” in doped silicon\n•\tHelped adapt simulation software code to the purpose of observing lattice defects

  Chemical & Biomolecular Engineering

  Just About Music (JAM)

  Cornell University

• Protein Engineering

  Chemistry

  Biomedical Sciences

  Research

  Biochemical Engineering

  Synthetic Biology

  Microbiology

  Biotechnology

  Biochemistry

  Molecular Biology

  Molecular Genetics

  Biofuels

  Metabolic Engineering

  Chemical Engineering

  Sustainable Energy

  Academia

  Green Chemistry

  Design and construction of acetyl-CoA overproducing Saccharomyces cerevisiae Strains

  Huimin Zhao

  Saccharomyces cerevisiae has increasingly been engineered as a cell factory for efficient and economic production of fuels and chemicals from renewable resources. Notably

  a wide variety of industrially important products are derived from the same precursor metabolite

  acetyl-CoA. However

  the limited supply of acetyl-CoA in the cytosol

  where biosynthesis generally happens

  often leads to low titer and yield of the desired products in yeast. In the present work

  combined strategies of disrupting competing pathways and introducing heterologous biosynthetic pathways were carried out to increase acetyl-CoA levels by using the CoA-dependent n-butanol production as a reporter. By inactivating ADH1 and ADH4 for ethanol formation and GPD1 and GPD2 for glycerol production

  the glycolytic flux was redirected towards acetyl-CoA

  resulting in 4-fold improvement in n-butanol production. Subsequent introduction of heterologous acetyl-CoA biosynthetic pathways

  including pyruvate dehydrogenase (PDH)

  ATP-dependent citrate lyase (ACL)

  and PDH-bypass

  further increased n-butanol production. Recombinant PDHs localized in the cytosol (cytoPDHs) were found to be the most efficient

  which increased n-butanol production by additional 3 fold. In total

  n-butanol titer and acetyl-CoA concentration were increased more than 12 fold and 3 fold

  respectively. By combining the most effective and complementary acetyl-CoA pathways

  more than 100 mg/L n-butanol could be produced using high cell density fermentation

  which represents the highest titer ever reported in yeast using the Clostridia CoA-dependent pathway.

  Design and construction of acetyl-CoA overproducing Saccharomyces cerevisiae Strains

  Huimin Zhao

  Saccharomyces cerevisiae has increasingly been engineered as a cell factory for efficient and economic production of fuels and chemicals from renewable resources. Notably

  a wide variety of industrially important products are derived from the same precursor metabolite

  acetyl-CoA. However

  the limited supply of acetyl-CoA in the cytosol

  where biosynthesis generally happens

  often leads to low titer and yield of the desired products in yeast. In the present work

  combined strategies of disrupting competing pathways and introducing heterologous biosynthetic pathways were carried out to increase acetyl-CoA levels by using the CoA-dependent n-butanol production as a reporter. By inactivating ADH1 and ADH4 for ethanol formation and GPD1 and GPD2 for glycerol production

  the glycolytic flux was redirected towards acetyl-CoA

  resulting in 4-fold improvement in n-butanol production. Subsequent introduction of heterologous acetyl-CoA biosynthetic pathways

  including pyruvate dehydrogenase (PDH)

  ATP-dependent citrate lyase (ACL)

  and PDH-bypass

  further increased n-butanol production. Recombinant PDHs localized in the cytosol (cytoPDHs) were found to be the most efficient

  which increased n-butanol production by additional 3 fold. In total

  n-butanol titer and acetyl-CoA concentration were increased more than 12 fold and 3 fold

  respectively. By combining the most effective and complementary acetyl-CoA pathways

  more than 100 mg/L n-butanol could be produced using high cell density fermentation

  which represents the highest titer ever reported in yeast using the Clostridia CoA-dependent pathway.

  Design and construction of acetyl-CoA overproducing Saccharomyces cerevisiae Strains

  huimin zhao

  The biocatalytic reduction of D-xylose to xylitol requires separation of the substrate from L-arabinose

  another major component of hemicellulosic hydrolysate. This step is necessitated by the innate promiscuity of xylose reductases

  which can efficiently reduce L-arabinose to L-arabinitol

  an unwanted byproduct. Unfortunately

  due to the epimeric nature of D-xylose and L-arabinose

  separation can be difficult

  leading to high production costs. To overcome this issue

  we engineered an E. coli strain to efficiently produce xylitol from D-xylose with minimal production of L-arabinitol byproduct. By combining this strain with a previously engineered xylose reductase mutant

  we were able to eliminate L-arabinitol formation and produce xylitol to near 100% purity from an equiweight mixture of D-xylose

  L-arabinose

  and D-glucose.

  Selective Reduction of Xylose to Xylitol from a Mixture of Hemicellulosic Sugars

  Ann Hochschild

  Bryce E Nickels

  Christopher D Wells

  Seth R Goldman

  eLife

  The σ subunit of bacterial RNA polymerase (RNAP) confers on the enzyme the ability to initiate promoter-specific transcription. Although σ factors are generally classified as initiation factors

  σ can also remain associated with

  and modulate the behavior of

  RNAP during elongation. Here we establish that the primary σ factor in Escherichia coli

  σ70

  can function as an elongation factor in vivo by loading directly onto the transcription elongation complex (TEC) in trans. We demonstrate that σ70 can bind in trans to TECs that emanate from either a σ70-dependent promoter or a promoter that is controlled by an alternative σ factor. We further demonstrate that binding of σ70 to the TEC in trans can have a particularly large impact on the dynamics of transcription elongation during stationary phase. Our findings establish a mechanism whereby the primary σ factor can exert direct effects on the composition of the entire transcriptome

  not just that portion that is produced under the control of σ70-dependent promoters.

  The primary σ factor in Escherichia coli can access the transcription elongation complex from solution in vivo

  Nair

  Bristol-Myers Squibb

  Harvard Medical School

  Merck

  Tufts University

  Regulation of Prokaryotic Transcription Initiation and Elongation\nMechanisms of Phage and Bacterial Transcription Antitermination

  Post doctoral fellow

  Greater Boston Area

  Harvard Medical School

  Medford

  MA

  Synthetic biology\nTranscriptional & post-transcriptional regulation\nProtein engineering\nMetabolic engineering\nSystems bioengineering\nProbiotics

  gut microbiota engineering

  Assistant Professor

  Tufts University

  Varivax manufacturing process support\n•\tConducted experiments to recommend ways to minimize potency losses at various stages of production of Varivax®\n•\tPerformed statistical studies to find correlations between raw material quality and final product quality\n•\tSupported the bulk manufacturing by performing experiments recommended to close out process deviation reports \n•\tDeveloped & verified an analytical model for post-heat sterilization equipment cool-down

  Intern

  Varivax®

  Viral Vaccine Technology & Engineering

  Greater Philadelphia Area

  Merck

  Process validation for antibody therapeutic purification\n•\tDevised and conducted experiments to improve chromatographic and filtration purification \n techniques for therapeutic proteins\n•\tDeveloped processes for isolating and purifying impurities for analytical standards\n•\tSupported and performed experiments for new product engineering runs\n•\tPerformed experiments required for Biologics License Application (BLA)

  Research Scientist

  Biotechnology Purification Development

  Syracuse

  New York Area

  Bristol-Myers Squibb

  American Institute of Chemical Engineers