Nanomaterials and Quorum Sensing
Quorum sensing (QS) is a cell-to-cell communication system that allows prokaryotic cells to detect their local population density and coordinate synchronized gene expression. QS regulates a wide variety of coordinated cell activity, including biofilm formation, virulence production, bioluminescence, antibiotic synthesis, filamentation, and conjugation. Bacteria are able to determine local cell numbers by producing and detecting small signaling molecules known as autoinducers.
We hypothesize that engineered nanoparticles may intercept and sequester autoinducer molecules and disrupt the synchronized gene expression. In order to examine this hypothesis experiments are being performed using Chromobacterium violaceum, and in vitro, using isolated cell components. Specifically, the capacity of ENPs to adsorb signaling molecules from C. violaceum, as well as those from other species, is examined. In addition to adsorption properties, biological assays will be used to determine if ENPs can be engineered to interfere with or permit natural QS behavior. Results from this work may be used as a guide for the future design of human health focused biotechnology and regulation of ENPs for reduced environmental impacts.
Nanomaterials and Horizontal Gene Transfer
Horizontal gene transfer (HGT) refers to the transfer of genes between organisms rather than to offspring. HGT is an important factor in the evolution of many organisms. Horizontal gene transfer is the primary reason for bacterial antibiotic resistance and plays an important role in the evolution of bacteria that can degrade xenobiotic novel compounds, and in the evolution, maintenance, and transmission of virulence. We are examining the role that engineered and natural nanomaterials may play in HGT. We hypothesize that nanomaterials stabilize DNA, induce cell stress, and increase the rates of HGT in microbial communities.
Nanomaterial Transformations and Coatings
Engineered nanomaterials acquire a variety of organic and inorganic coatings. Both manufactured and natural nanomaterials in the environment will undergo various biological and geochemical transformations that their transport, fate, and interactions with the biotic and abiotic environment. Our research is identifying and classifying the types of transformations that engineered and natural nanomaterials undergo in the environment. We focus on research questions relate to redox reactions, and on the role of polymeric coatings, including NOM on the behavior of nanomaterials with respect to their interactions with bacterial cells, for example:
How do the characteristics of the coatings affect a nanoparticle’s environmental behavior?
What impact do transformations have on the environmental behavior of nanomaterials?
How are the interactions between nanomaterials and microbial populations and communities impacted by coatings and transformations?