Current Research Projects in the Westenberg Lab
Plant Microbe Interactions – Symbiotic Nitrogen fixation
Several current projects in the Westenberg lab center around soil microorganisms and their role in agriculture and phytoremediation. Arguably, one of the most important plant-microbe relationships in the state of Missouri is the symbiosis between the nitrogen fixing soil bacterium Bradyrhizobium japonicum and its host, Glycine max (soybean). Research projects initially revolved around the structure, function and regulation of respiratory enzymes such as succinate dehydrogenase and NADH dehydrogenase and this remains an area of interest. We have learned that some commonly used seed applied fungicides inhibit the growth of B. japonicum by blocking the respiratory chain and we have studied the impact of fungicides and other field applicants on the growth of rhizobia and the broader soil community.
Plant-Microbe Interactions – Quorum Sensing in B. japonicum
To better understand the limited competitiveness of laboratory strains relative to commercial inoculants and native soil strains we are also characterizing bacterial signal molecules, called autoinducers, which are involved in a gene regulation phenomenon referred to as quorum sensing. Our working hypothesis is that production of autonducer molecules during the growth of commercial inoculants at high cell densities leads to gene expression patterns that are unfavorable for efficient infection of the host plant. The availability of the complete B. japonicum genome has facilitated this research and has led to the identification of a single known autoinducer synthase gene and several potential autoinducer response regulators in strain USDA 110.
Plant-Microbe Interactions – Drought Tolerance
We are interested in reducing the impact of drought on symbiotic nitrogen fixation. A colleague at National Chung Hsing University in Taiwan, Dr. Mei-Chin Lai, identified genes from a marine methanogen that can increase the salt tolerance of E. coli and Arabidopsis thaliana so we are testing to see if introducing the genes into B. japonicum will increase drought tolerance using salt tolerance as a surrogate for drought tolerance.
Plant-Microbe Interactions – Phytoremediation
We are exploring the partnership between plants and microbes in the rhizosphere to clean up environmental pollutants and survival of plants in toxic environments. This work is being done in collaboration with Dr. Joel Burken in Civil, Architectural, and Environmental Engineering here at Missouri S&T,
Antibacterial Bioactive Glass and other Antibacterial treatments
Another research focus in the laboratory is a collaboration with colleagues in Ceramic Engineering who are developing bioactive glass for bone and tissue repair. Students in my lab are studying the antibacterial properties of these glass formulations and the mechanism underlying the inhibition of bacterial growth. Using a large collection of Gram-positive and Gram-negative bacteria, several with clinical relevance, we are exploring the broad-spectrum antibacterial activity of different glass formulations with different additions of antibacterial agents. We have developed a number of assays to asses viability and specific types of damage to bacterial cells. We are also interested in the ability of these materials to inhibit the growth of biofilms on medical devices. This has led to further collaborations with colleagues in Chemistry and Chemical and Biochemical Engineering to investigate other antibacterial processes.
Other Collaborations – Microbes Rule!
Our laboratory has a diverse collection of microbes and is always interested in expanding our collection and exploring new collaborations. One of the earliest collaborations with Dr. Dan Armstrong in the Department of Chemistry (now at UT-Arlington) in which we explored using capillary electrophoresis to separate microbes. Recent collaborations include conversion of glycerol to ethanol to address the excess glycerol produced by biofuel production. A related collaboration is exploring methods to enhance electricity generation in microbial fuel cells. Other collaborations include using bacteria to produce useful aggregates of fines from concrete recycling (see image to the right). In response to the Covid-19 pandemic we have collaborated with colleagues to use bacteriophages to explore strategies to disinfect air handling systems and to test filtration methods. Recent collaborations with a colleague in Chemistry is using single-cell ICP-MS to explore interaction of copper and silver nanoparticles with various bacteria, including Legionella pneumophila. A fun new project has been exploring microbes from the campus nuclear reactor pool with students from the campus nuclear engineering program.
