Presented at Asia-Pacific Biofilms 2024 | Guangzhou, China | November 2024
In November 2024, at the Asia-Pacific Biofilms 2024 conference in Guangzhou, China, presented this research on biofilm formation and extracellular polymeric substances (EPS) production by perchlorate-reducing microorganisms, specifically isolated from the serpentine soils of Ussangoda National Park (UNP), Sri Lanka. The research has significant implications for bioremediation, particularly for environments that mimic Martian soil conditions.
Research Overview
The study primarily focuses on the perchlorate reduction capabilities of microbial isolates from the Ussangoda National Park, which is known for its unique serpentine soils. These soils share similar elemental properties with Martian regolith, which makes them an ideal candidate for research on microbial bioremediation in extreme conditions. The microbial isolates in this study include a perchlorate-reducing bacterium (PRB, n=1) and three perchlorate-tolerant fungi species (n=3), all screened for their ability to reduce perchlorate ions under controlled conditions.
Microbial Isolates and Their Potential
The microbial isolates were cultured in selective media designed for perchlorate-reducing bacteria, with a concentration of 0.02 mol/dm³ sodium perchlorate (NaClO₄). These cultures were then screened for their perchlorate reduction efficiency using FTIR analysis. Among the fungal-bacterial combinations, the AW combination demonstrated the highest perchlorate reduction efficiency at 60.9%, followed by AY at 48.8%, while the control cultures showed minimal reduction.
Biofilm Formation: The Key to Efficient Bioremediation
An important aspect of the study was investigating the biofilm formation by these microorganisms. Biofilms are clusters of microorganisms encased in a protective extracellular matrix, known as extracellular polymeric substances (EPS), which enhance microbial resistance to environmental stressors, such as high concentrations of perchlorate.
The Congo Red agar method, followed by UV spectrophotometry, was employed to investigate and quantify the biofilm formation. The results showed that the microbial combinations of AP and AW formed biofilms within 72 hours, while AY took up to 14 days for biofilm formation. At a low concentration (0.1 mg/L) of Congo Red, the absorbance of the AP biofilm was significantly higher (2.587) than the control (1.516), indicating a higher level of EPS production. Similar results were observed at the higher concentration of Congo Red, confirming the biofilm-forming potential of these microbial combinations.
Implications for Mars and Earth Bioremediation
The promising results of this study point to the significant potential of using these biofilm-forming microorganisms for perchlorate reduction in extreme environments. Given the elemental similarity between UNP soils and Martian regolith, this research opens up possibilities for bioremediation on Mars. As perchlorate contamination has been detected in Martian soils, these biofilms could potentially serve as a tool for cleaning up perchlorate-contaminated sites on Mars.
Back on Earth, these findings also offer hope for improving bioremediation strategies for perchlorate-contaminated soils, a widespread issue in various industrial sites.
Future Directions
The next phase of this research will focus on refining the quantification methods for biofilm biomass and evaluating the long-term efficiency of perchlorate reduction under more challenging environmental conditions. Additionally, mass culturing of the selected biofilms will be explored to scale up their application for bioremediation purposes.
I invite you to read the full research article on ResearchGate, where I provide a comprehensive analysis of these findings and discuss the implications for both space exploration and Earth-based environmental management.