Expanding our Understanding of How Microbes Interact with Charged Surfaces
Abstract
Microbial interactions with surfaces via formation of biofilms have important implications in bioenergy, biofouling, biofilm formation, and the infection of plants and animals. Despite this, our understanding of these interactions is remarkably incomplete. An important property of any surface is its intrinsic charge, and electrostatic forces represent the earliest interactions of microbes with surfaces. Most natural surfaces and microbes carry a net negative charge. Yet microbes readily interact with such surfaces. Most of what we know about the ability of microbes to interact with charged surfaces comes from the microbial fuel cell field where people have studied in some depth how Geobacter and Shewanella interact with positively charged surfaces while using them as electron acceptors via a process called reductive extracellular electron transfer (reductive EET). The interaction of microbes with negatively charged surfaces where microbes use them as electron donors directly (a.k.a. oxidative EET) has come to the fore only recently. As a consequence, very little is known about this process. Importantly, oxidative EET represents an ideal test case to study the ability of microbes to interact with negatively charged surfaces. Key questions that we intend to answer are (1) What are the dynamics of short and long term microbial interactions with negatively charged surfaces? (2) What mechanisms underlie these interactions? We choose the organism Rhodopseudomonas palustris TIE-1 as a model for oxidative EET. TIE-1 was observed to accumulate unknown proteins at the point of contact with negatively charged surfaces. Moreover, we have many different relevant mutants already constructed in this organism and have relatively advanced genetic tools in it as well. Before we can answer some of these fundamental questions, we face three major challenges. The first major challenge is our inability to visualize these processes at the microscopic level using the current technology. The second major challenge is the lack of throughput in studying microbial interactions with charged surfaces using bioelectrochemical reactors. The third major challenge requiring development is that of super-resolution microscopy under anaerobic conditions to allow visualization of the localization of proteins and other components critical for microbial attachment to charged surfaces. In our proposed research, we tackle all these three challenges by developing a microscopic, microfluidic, bioelectrochemical system compatible with bio-imaging. This represents a major advance in the current technology available to a variety of researchers from numerous fields. Preliminary results obtained using a prototype miniaturized device recapitulate previous results and highlight the strengths of our methodology to make new discoveries. We have also identified new fluorophores that will allow us to use super-resolution imaging to explore the molecular underpinnings of microbial interactions with charged surfaces. Our proposed research will lead to a novel bioelectrochemical device that would aid fundamental cell biological studies in microbiology, cancer biology and neurobiology. Due to its broad applicability, such a device will be of direct value to the Army by furthering research toward Òoptimizing warfighter physical and mental performance capabilities, and a range of revolutionary applications to protect the SoldierÓ. The fundamental knowledge on how microbes interact with charged surfaces that would be revealed by the proposed research would help Òunderstand the underlying properties, principles, and mechanisms governing DNA, RNA, proteins, organelles, cells, organisms, multi-species interactionsÓ. This knowledge will ultimately help provide solutions to potential issues affecting the Soldier such as disease and/or others annoyances caused by microbes that attach to charged surfaces in the human body, and to prosthetics.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 07, 2018
- Source ID
- W911NF1810037
Entities
People
- Arpita Bose
Organizations
- Army Contracting Command
- United States Army
- Washington University in St. Louis