Mathematical Biology seminar Isaac Klapper Temple University "Microbial Communities in Their Physical Environments" Tuesday, January 27, 2026 1-2pm in LCB 215 Abstract: Microbes are found nearly everywhere on, in, and around the earth, generally living in mixed species communities that are carefully tuned to their local physical environmental conditions. In this talk two examples of such communities will be presented, describing how they interact with local conditions and possibly alter them for advantage. First, we will discuss subaerial biofilms (SABs), microbial communities that colonize air-exposed interfaces, focusing in particular on stone surface environments. SAB function is tightly coupled to local conditions which are frequently harsh, particularly with respect to water availability. Even without exposure to regular rainfall, we hypothesize that overnight radiative cooling allow SABs to utilize condensation, i.e., dew, to gather high activity water, in order to be productive during the early morning before evaporation becomes significant. Further, we propose that SABs are able to effectively seal substratum pores to store condensed (or precipitated) water to offset evaporation for some time. A physical theory will be provided, based on the Hertz-Knudsen equation for describing evaporation/condensation at liquid-gas interfaces. The second focus environment is the bottom layer of sea ice. Sea ice is an interestingly complicated material consisting of a mixture of solid water ice and liquid brine phases which are coupled by thermodynamic considerations. It also is a (seemingly difficult) platform for microbial life, lots of it in fact, that uses the ice as a sort of shelter though eventually forming the foundation of the local food chain. A model will be presented that hypothesizes how, the resident microbial population might, via influence on brine osmolarity, impact sea ice material properties in order to induce internal convective flow.