Researcher(s)
- Austin Chambers, Biological Sciences, Delaware Technical Community College
Faculty Mentor(s)
- Clara Chan, College of Earth, Ocean and Environment, University of Delaware
Abstract
Leptothrix cholodnii SP-6 is a freshwater bacteria that can oxidize Fe(II) to produce insoluble Fe(III). The products of its iron oxidation are visible to the naked eye as environmental iron mats, but the mechanisms of how it performs iron oxidation are unknown. As an iron-oxidizer, L. cholodnii SP-6 needs more iron than most other bacteria to live. As such, iron is present in higher concentrations in its media compared to other bacteria. This makes it difficult to accurately measure its cell growth with optical density due to the interference from insoluble Fe(III) in cultures. L. cholodnii SP-6 is difficult to count manually under a microscope due to its shape and tendency to form dense clusters; additionally, manual cell counts are time-consuming. A high-throughput cell quantification method based on fluorescence would be a useful asset for monitoring cultures of iron oxidizers. My primary research goal is to determine if microplate readers measuring fluorescence from a nucleic acid dye can accurately quantify cell growth of L. cholodnii SP-6. I have been modifying plate reader conditions to get consistent readings and the outcome should be an optimized procedure which can be used to get accurate measurements of SP-6 cell growth. This would be useful for evaluating the growth of SP-6 on different combinations of nutrients, such as carbon and iron. For the second goal of my project, I created a tool that will search genomes for multicopper oxidases (MCOs), which are potential metal-oxidizing proteins. The tool is a python program which searches an input fasta file of protein sequences and records any sequences that contain certain motifs, which are pairs of short sequences found in all MCOs. This tool rapidly identifies these proteins in bacterial genomes and can be used to discover specific MCOs that may be widespread among iron oxidizers. When a MCO is identified, it can be tested for its roles in iron oxidation which could distinguish novel iron oxidases.