Research description

First and foremost I would like to express my sincere gratitude to Dr.Gilcrease for his constant and generous guidance, help and encouragement throughout my research study (Jan’02-Dec’03). I am Sowmya Talari, a Graduate Student in Chemical Engineering at South Dakota School of Mines & Technology. I grew up in Hyderabad, India and I completed my undergraduate studies from Osmania University, India. I am honored to be a part of this research group working on a US Air Force Project, titled “Biocatalysis for the Synthesis of Polymer Precursors”.

The goal of our project is to synthesize high-temperature resistant polymers that can withstand temperatures as high as 265°C. Recombinant E.coli cells expressing toluene/benzene monooxygenase enzymes are used in the regiospecific hydroxylation of biphenyl and diphenylacetylene at the meta position. Low solubilities of these substrates in aqueous solution have been found to be the possible reasons for lower biocatalaysis rates. The biocatalysis of sparingly soluble substrates may be enhanced by surfactants. The present work concentrates on increasing the aqueous solubility of sparingly soluble substrates.

Surfactants play a major role in biological systems. In cell cultures, the addition of surfactants influences the cellular permeability, thereby increasing substrate transport to the intracellular enzyme; however, surfactants may also be toxic or act as a competitive substrate. Four different surfactants, (Zonyl, Sodium dodecyl sulfate, Triton X-100 and Cetyltrimethylammonium bromide) are being evaluated on Diphenylacetylene biocatalysis rates. High performance liquid chromatography (HPLC) is used for the quantification of biphenyl/diphenylacetylene and the hydroxylated products.The cell concentrations are monitored with the help of a Scanning Spectrophotometer. 

Presentations:

• “Biocatalysis for the Synthesis of Polymer Precursors” (poster presentation) at Student Research Poster Session, Pierre, South Dakota, February 2002.

• “Biocatalysis of Biphenyl to Synthesize Polymer Precursors” (poster presentation) at 32nd Annual Biochemical Engineering Symposium, Iowa State University, Iowa, October 2002.

• “Use of surfactants in the whole-cell biocatalysis of sparingly soluble substrates” (accepted and approved for poster presentation) at 2003Annual Meeting, Society for Industrial Microbiology, Minneapolis, August 2003.