Maximizing Acetyl-CoA Output by Genetically Engineering E. coli for the Overall Output of the Bioplastic PHB; Social Media: How Proponents of Digital Media Maximize Content Consumption

Park, Sang-Hoon, School of Engineering and Applied Science, University of Virginia
Kester, Mark, MD-PHAR Pharmacology, University of Virginia
Earle, Joshua, EN-Engineering and Society, University of Virginia
Norton, Peter, EN-Engineering and Society, University of Virginia

In system optimization, a system is typically modified to improve its productivity, which can be defined as the ratio of outputs to inputs and the ratio of desired to undesired outputs. Yet not everyone shares in the management of a system, and when the those who are affected by the outputs are not the system managers, system optimization may subject others to ever-worsening outputs. For example, in the plastics industries, optimization of manufacturing systems increased productivity, yielding desirable outputs for some, such as a profitable product for manufacturers and inexpensive and practical goods for consumers. But for the earth’s ecosystems, optimization in this case meant degradation. Similarly, as tech companies and advertisers optimized social media platforms to maximize data collection, many social media users found their attentions colonized and their preferences mined; moreover, the exploitation of cognitive biases for maximum user engagement caused social and political turmoil. In the case of systems that find significant practical, real-world applications, true system optimization, far from the bounded, technical task that it is often mistaken for, is in fact a complex and unbounded sociotechnical problem that defies definitive solution.

The following technical project investigates the optimization of biodegradable plastics production at the microscale level, incorporating genetic engineering and metabolic models to improve yields of these plastics secreted from bacteria. Unsustainable practices in the production, use, and disposal of single-use plastics have promoted the adoption of alternative bioplastics that are natural and biodegradable. Efforts are currently underway in the renewable plastics industry to streamline production and distribution of these plastics. Our sponsor, Transfoam LLC, has recently developed a modified E. coli strain capable of producing polyhydroxybutyrate (PHB) from styrofoam monomers (styrene) with the inclusion of the pha plasmid from P. putida and the sty plasmid from C. necator. Here, we incorporate findings from literature to propose the deletion of the ackA and pta genes to reduce loss of carbon flux to acetate production and increase the net yield of acetyl-CoA, the primary metabolite feeding into PHB production. These gene knockouts were performed on the E. coli DH5α cell line using a combination of the CRISPR-Cas9 and lambda red protocols. Acetyl-CoA concentrations were quantified fluorometrically and normalized with their respective cell culture wet weight to result in 0.041±0.006, 0.027±0.007, and 0.039±0.007 μM/mg for ΔackA, Δpta, and control, respectively. ΔackA resulted in significantly lower acetyl-CoA concentrations than both control and Δpta (p<0.05). In addition to these results, perturbations performed on the published iML1515 E. coli K-12 MG1655 genome- scale metabolic model inform of additional gene deletions that could further improve upon these results, including ΔsucC, ΔcitE, ΔatoA, and ΔaldB. These additional knockouts show potential in coupling PHB production to cell growth on glucose-based substrates, guaranteeing a baseline rate of PHB production provided that cells are actively growing. Our procedures here not only tangibly improve PHB yields in E. coli to the benefit of our sponsor, but also inspire additional possibilities in bioengineering that contribute to the growing movement for environmental concern and sustainability.

The sociotechnical report that follows investigates the role of social media in facilitating quantifiable increases in ideological polarization, mental illness, and loneliness in our society. These trends are correlated to the time people spend consuming digital media, which has increased steadily over the past decade to concerning levels. While the increase in social media consumption can partially be attributed to innovations in hardware that have improved speeds, connectivity, and accessibility, many findings point to conscious design choices of the software and interfaces employed by social media platforms as the primary contributing factor. These platforms have specifically been designed to maximize user engagement and attention over time to increase the profits they generate. Supporting evidence, which comes in the form of academic studies, coverage and opinion pieces by the general media, and statements released by social media platforms themselves, provides a more detailed understanding of the issues at hand. In proposing a solution to these concerns, the discussion invokes past and current efforts of advocacies and governments to respond to these developments in the industry and addresses what users are currently able to do. Most importantly, the results strongly suggest the need for greater awareness of how social media platforms are designed, so that users can not only adopt safer habits individually, but work collectively to empower our sluggish public institutions. We must hold social media platforms more accountable for their priorities and design choices.

BS (Bachelor of Science)
system optimization, genetic engineering, social media
Issued Date: