Today's Messages

Please join the Biology Department and the Great Lakes Center for the seminar “Chemical Conversations in Soil: Microbial and Plant Signals Shape Community Behavior,” presented by Dr. Kasia Dubiel on Monday, April 20, at 3:00 p.m. in SAMC 151.

Abstract: Soil ecosystems are structured by complex chemical interactions among plants and microorganisms. These small molecules shape microbial behavior and community composition. In these ecosystems, both invasive plants and soil-dwelling microbes deploy bioactive compounds that influence growth, differentiation, and competitive outcomes. Here, we examine how chemically mediated interactions drive soil microbial dynamics across plant–microbe and microbe–microbe systems.

First, we explore chemically-mediated interactions within multispecies microbial biofilms using a coculture system composed of Bacillus subtilis and Pantoea agglomerans. Biofilms are collections of microorganisms encased by a self-produced extracellular matrix that acts as a protective barrier from environmental stressors. Interestingly, B. subtilis and P. agglomerans form structurally-unique biofilms with altered sporulation and specialized metabolite production in coculture compared to monoculture. Based on our data, we hypothesize that the presence of P. agglomerans and coculture-specific compounds alter B. subtilis sporulation.

Second, we investigate the chemical strategies employed by the invasive plant Reynoutria japonica (Japanese knotweed), which releases phenolic compounds into surrounding soils. We assessed the effects of knotweed-associated phenolics on bacterial isolates derived from diverse plant-associated soils and from knotweed-dominated soils. Preliminary results reveal altered bacterial growth and biofilm formation in the presence of these phenolics, suggesting that knotweed-derived phenolics may directly alter soil microbial communities and contribute to invasion success through chemical interference. 

Together, these studies demonstrate that chemical signals, originating from both plants and microbes, play a central role in shaping microbial behavior and community structure. By integrating plant-driven allelopathy with microbe-microbe signaling, this work highlights chemical mediation as a unifying mechanism underlying soil ecosystem interactions.