Detail:

Abstract:
　　The microbes inhabit planet earth over billions of years, and have adapted to diverse physical environment of water, soil, and particularly at or near interfaces. Following recent studies on bacterial swimming and accumulation near solid surfaces, we turned our attention to the behavior of Caulobacter crescentus, a singly flagellated bacterium at the interface of water/air or water/oil. Our ongoing study suggests that, besides most properties caused by a boundary confinement like that of the water/solid interface, the Caulobacter swarmer cells tend to get physically trapped at either water/air or water/oil interface. They continue to move in tight circles, and with speed reduced by about half at the air surface, compared with their bulk speed, and even slower at the water/oil interface. The experimental data call for analysis based on low Reynolds number hydrodynamics, the known surface tension and surface viscosity at the interface. The overall goal of our study is to describe interfacial microbial functions through detailed analysis of their motion based on classical fluid physics.

Speaker Biography
 　　Professor Jay Xin Tang, Chinese name Tang Jian-xin, received his BS in physics from Peking University in 1987, and came to the US for graduate study through the China and the US Physics Examination and Application (CUSPEA) program established by Professor TD Lee. He received PhD in Physics from Brandeis University. After postdoctoral training at Harvard Medical School, he became an assistant professor of physics at Indiana University in 1999. Since 2003 he has been on the faculty of Brown University, first as an assistant professor and then associate professor of physics and engineering. Prof. Tang's research area is experimental biophysics, with topics covering morphology, pattern formation, force generation and motility of cells. Professor Tang has published over 80 original research papers and received several research awards from National Science Foundation, National Institute of Health, and travel awards such as one from Kuanchen Wang Foundation and another from Santander Universities. Prof. Tang is a life member of the American Physical Society. He is also a member of the Biophysical Society and the American Society of Microbiology. Outside academia, he serves as a board member of the Peking University Alumni Association in the New England Area. His hobby in the game of contract bridge has brought him to the rank of a Silver Life Master.