USAFA - iGEM 2024

Mission Statement

This project focuses on developing a method of biosilicification for enhancing the brick formation process, minimizing ammonium release, and exploring potential applications of biocement, like dust mitigation and growing plants.

Introduction and Background

Biocementation is an environmentally friendly method that leverages the natural enzymatic processes of bacteria to create solid structures like bricks. One prominent form of this process utilizes the bacterium Sporosarcina pasteurii to induce calcite formation in the presence of calcium ions and urea—a process known as Microbially Induced Calcite Precipitation (MICP) (Achal, Mukherjee, 2015). Unlike traditional cement production, which is energy-intensive, resource-demanding, and a significant source of CO₂ emissions, biocementation offers a more sustainable alternative. However, a significant byproduct of MICP is ammonium, which poses environmental management challenges due to potential contamination from runoff (Esteban et al., 2016).

To address this issue, the 2024 USAFA iGEM team focused on an alternative process called biosilicification, which involves silicatein-based biocementation. The team employed a strain of E. coli engineered with the INP-silicatein-α gene (INP-sil) to facilitate silica formation, aiming to develop an effective cementation solution. To explore the various implications of biosilicification, the team was divided into three sub-groups: the Bricks Team, the Real-World Application Team, and the Biomineralization/Ammonium Team.

Team Aims

Brick Team: To develop a more environmentally friendly biocement, we are genetically engineering E. coli with INP-sil to produce silica as a binding substrate. This approach aims to reduce both carbon and ammonium emissions by utilizing a process that eliminates ammonium as a byproduct.

Biomineralization/Ammonium Team: The primary test was to verify the production of silicon dioxide bonds by E. coli INP-sil while also creating an amorphous aluminosilicate when added to an aluminum rich environment. We wanted to compare the relative ammonium concentrations of E. coli INP-sil vs S. pasteurii to verify that our claim of being more environmentally friendly was well founded.

Real World Application Team: The goal of our experiments is to test if biocementation is an effective method to reduce the rising problem of desertification across the globe and in our local community. In addition, we aim to discover if biocemented soil can be used for agriculture and sustaining plant life to combat reducing farmable land.

Sources

• Achal V., Mukherjee A. (2015). A review of microbial precipitation for sustainable construction. Construction and Building Materials, Volume 93, https://doi.org/10.1016/j.conbuildmat.2015.04.051.
• Esteban R., Ariz I., Cruz C., Moran J.F. (2016). Review: Mechanisms of ammonium toxicity and the quest for tolerance, Plant Science, Volume 248, https://doi.org/10.1016/j.plantsci.2016.04.008.