Biological Reduction of Perchlorate in Martian Regolith Simulant Using Azospira Oryzae

Authors

Brianna Bernhardt, University of Nebraska-LincolnFollow

First Advisor

Yufeng Ge

Date of this Version

5-2025

Document Type

Thesis

Citation

Bernhardt, B. 2025. Biological Reduction of Perchlorate in Martian Regolith Simulant Using Azospira Oryzae. Undergraduate Honors Thesis. University of Nebraska-Lincoln.

Comments

Copyright Brianna Bernhardt 2025

Abstract

Establishing a sustainable human presence on Mars will require in-situ resource utilization (ISRU) to reduce costly and inefficient resupply missions. Despite containing many of the requirements for agriculture, Martian regolith is contaminated with toxic levels of perchlorate (ClO₄^-), threatening human health and agricultural success. Biological remediation using perchlorate-reducing bacteria offers a promising approach to address these challenges. This study investigated the perchlorate-reducing ability of Azospira oryzae, a facultative anaerobe capable of converting ClO₄^- to chloride (Cl^-) through dissimilatory respiration. A. oryzae was cultured in Martian regolith simulant (MGS-1) amended with 0.0%, 0.5%, and 1.0% perchlorate by weight. Three assays were completed to assess reduction: OD₆₀₀ measurements to track bacterial growth, a methylene blue colorimetric assay to measure perchlorate concentration, and a silver nitrate titration to measure chloride production. The use of multiple assays aimed to depict the depletion of perchlorate and production of chloride, providing insight into the full scope of this reduction pathway. The findings contribute to our understanding of how microbes may be applied in future perchlorate bioremediation efforts as part of ISRU strategies for extraterrestrial agriculture.