Colleen Friel - Graduated Summer 2018
My PhD research focused on the carbon for nitrogen exchange between plants and nitrogen fixing bacteria called rhizobia. This interaction could provide an alternative to environmentally costly synthetic nitrogen fertilizers. However, not all plants are able to interact with rhizobia, and we do not fully understand the signal exchange and trade negotiations that determine the cost:benefit ratio of this interaction for the plant. My PhD work focused on exploring the factors that determine how many resources plants allocate to their rhizobial partners.
Participating in the PBHS program was particularly valuable to me since my PhD lab was focused on ecology and evolution, with few connections to industry. The classes and symposia that I attended through PBHS helped me learn about the exciting advances happening in plant biotechnology in industry, and to expand my professional network in the field. In fact, I first connected with my current PI at the 2017 PBHS symposium. I am now a postdoc in Cecilia Martinez-Gomez's lab at Michigan State University. I am studying the role of lanthanide biochemistry in the interactions between crops and methylotrophic bacteria. The goal of the project is to elucidate the mechanism of lanthanide-mediated plant growth promotion by methylotrophs and to develop commercial inoculants for various crops.
Emily Wrenbeck - Graduated summer 2017
The focus of my PhD research was to gain better understanding of the constraints of functional enzyme evolution using a research technology pipeline developed by the Whitehead Lab. In brief, the pipeline involved coupling high-throughput screens or selections for protein function to deep sequencing to generate datasets containing information on thousands of mutations of a protein sequence. This was applied to study how enzymes encode substrate specificity, which is currently not well understood, by performing functional selections for an enzyme on multiple substrates. In this work, I found that specificity is globally encoded throughout protein sequence and structure. In addition, during my PhD I co-developed Nicking Mutagenesis, a method for the construction of comprehensive single-site saturation mutagenesis DNA libraries that requires only double-stranded plasmid DNA as input substrate. This method was validated on several gene targets and plasmids and is currently being used in academic, government, and industry laboratories worldwide.
During my time in the training program I was exposed to new areas of research and ways of thinking that undoubtedly influenced my scientific interests and career goals. Specifically, from the material covered in program courses and the lectures given by invited speakers at the annual symposia I became captivated with the idea of biomanufacturing and natural product synthesis in engineered microbes. This led me to pursue a related research project and ultimately to a collaboration between the Whitehead Lab (Dept. of Chemical Engineering) and the Barry Lab (Dept. of Horticulture and another training lab). In brief, this project entailed applying the research pipeline to engineer improved heterologous expression of an enzyme from the Atropa belladonna medicinal Tropane Alkaloids pathway recently discovered by the Barry Lab, with the ultimate goal of improving productivity of an engineered Tropane Alkaloids biosynthetic pathway in yeast. These program-inspired interests will be continued this fall when I begin my career as a scientist at Ginkgo Bioworks (Boston, MA) with the title of Protein Engineer. I hope to expand my knowledge of natural product synthesis and state-of-the-art technologies for engineering biology, be part of developing a world-class protein engineering group, and glean insight into the business workings of a biotechnology company.