Discipline: Ecology Environmental and Earth Sciences
Room: Exhibit Hall A
Camille Bradshaw - Dodge City Community College
Co-Author(s): Javil Hansen, Kansas State University, Kansas, Manhattan; Matthew Kirk, Kansas State University, Kansas, Manhattan
Microbes play important roles in the environment because they affect the quality of water and soil resources and the abundance of greenhouse gases. By understanding environmental controls on microbes, we can better understand how microbes will be affected by the environmental changes. pH is important because it shapes microbial metabolisms in different ways such as affecting conditions for growth and survival, and interferes with metabolisms. Knowing what pH limit affects certain things in the environment can help reduce harmful environmental changes such, as global warming. We tested the hypothesis that the upper pH limit for Geobacter metallireducers is lower for cultures with goethite than cultures with ferrihydrite. We tested this hypothesis by growing cultures of G. metallireducers for 19 days at various pH levels (5-8) with either goethite (FeOOH) or ferrihydrite (~Fe(OH)3). We evaluated the amount of iron reduction by measuring the total concentration of ferrous iron (Fe(II)), the main product of iron reduction, at the end of the incubation. Results show that more iron reduction occurred in cultures with goethite than ferrihydrite. In cultures with goethite, between pH 6 and 7.5, 35 mg/L of ferrous iron was produced but at pH 5.5 and 8, little ferrous iron production occurred. Thus, the results suggest that the optimal pH for G. metallireducens in cultures with goethite is between 6 and 7.5. In contrast, little ferrous iron was produced at all with pH levels in cultures with ferrihydrite. The pH of the culture fluid also changed considerably during the incubation in both biologically-active and sterile control cultures with ferrihydrite, suggesting abiotic reactions were significant. Additional experiments are needed to fully test our hypothesis. References: Jin, Qusheng and Kirk, Matthew F. 01 May 2018. pH as a Primary Control in Environmental Microbiology: 1. Thermodynamic Perspective. Funder Acknowledgement(s): Funding was provided by KS-LSAMP supported by National Science Foundation (NSF) under grant number 1305059 and grant 1753436 (PI Kirk).
Faculty Advisor/Mentor: Matthew Kirk, firstname.lastname@example.org
Funder Acknowledgement(s): Funding was provided by KS-LSAMP supported by National Science Foundation under grant number 1305059; Funding was provided by grant 1753436 (PI Kirk)
Faculty Advisor: Dr. Matthew Kirk, email@example.com
Role: I worked with Javil Hansen, graduate student, during the whole experiment. He showed me how to do certain things and expected me to perform them efficiently. Working with anaerobic cultures requires caution since oxygen cannot interfere with the experiment, so Javil and I worked together on making sure the experiment went well. I also recorded and kept track of data while we carried out the experiment.