Sara Molinari
De novo-engineered living materials from bacteria
Abstract:
Engineered living materials (ELMs) are composites that integrate living cells within a biopolymer matrix, drawing inspiration from natural biological materials while leveraging synthetic biology to introduce programmable functions. Our laboratory develops de novo engineered living materials that emerge from bacteria genetically engineered to self-assemble into macroscopic structures. A foundational principle of this work is that reversible interactions distributed along a peptide’s length enable centimeter-scale assemblies, whereas strong pairwise interactions between cognate peptides yield only microscale structures. We propose that reversible weak bonds allow the system to sample lower-energy configurations, promoting the formation of larger, more stable structures. We validated this concept by displaying elastin-like polypeptides (ELP) on the surface of Escherichia coli. We then systematically varied the ELP sequence and chain length to connect molecular design with cell-surface properties and emergent collective behaviors. ELP display broadly increases bacterial surface hydrophobicity and alters surface charge. Guest-residue identity primarily determines display efficiency, while sequence chemistry and chain length tune the number, size, and morphology of ELMs. Importantly, bulk hydrophobicity and surface charge alone do not fully predict assembly, indicating that sequence-dependent interactions and peptide organization at the cell surface jointly determine material properties. Beyond self-assembly, these engineered surfaces modulate interactions with other bacterial species and enable bacteria to stabilize oil-water interfaces. When implemented in a production strain, programmable self-assembly facilitates biomass separation without compromising bioproduction performance, illustrating its potential utility in biomanufacturing. Together, this work establishes reversible, sequence-programmable surface interactions as a general strategy for connecting peptide design to bacterial interfacial behavior, living-material properties, and practical function.
Speaker: Sara Molinari, Fischell Department of Bioengineering
Dr. Sara Molinari earned her Ph.D. from the Systems, Synthetic, and Physical Biology program at Rice University, where she focused on programming genetic differentiation in bacteria. Her pioneering work, supported by DARPA’s Engineered Living Materials program, positioned her at the forefront of the field. As a postdoctoral researcher, she developed the first macroscopic living material grown from engineered bacteria. This innovative material, the only one of its kind, can hierarchically assemble cells across five orders of magnitude and allows for genetic control of its mechanical and catalytic properties. Currently, in her lab at the Department of Bioengineering at the University of Maryland College Park, Dr. Molinari explores the design principles for creating new Engineered Living Materials (ELMs) from various bacteria, aiming to broaden their practical applications. She is an active member of the Sigma Xi Scientific Research Honor Society, a 2022 Distinguished Young Scholar (UWDYSS), a 2022 BME Future Faculty, and a recognized rising star in the SynBYSS seminar series. In 2025 she received the NIGMS Maximizing Investigators' Research Award (MIRA) (R35).
Host: Jeffery Klauda
Seminars start at 4:00 pm, and refreshments will be served at 3:45 pm. All seminars are held in the 2136 Physical Sciences Complex (#415) unless otherwise noted.